Patent Application
20080063656
Adenoviruses are nonenveloped, icosahedral viruses that have been identified in several avian and mammalian hosts; Horne et al., 1959 J. Mol. Biol. 1:84-86; Horwitz, 1990 In Virology, eds. B. N. Fields and D. M. Knipe, pps. 1679-1721. The first human adenoviruses (Ads) were isolated over four decades ago. Since then, over 100 distinct adenoviral serotypes have been isolated which infect various mammalian species, 51 of which are of human origin; Straus, 1984, In The Adenoviruses, ed. H. Ginsberg, pps. 451-498, New York:Plenus Press; Hierholzer et al., 1988 J. Infect. Dis. 158:804-813; Schnurr and Dondero, 1993, Intervirology; 36:79-83; De Jong et al., 1999 J Clin Microbiol., 37:3940-5. The human serotypes have been categorized into six subgenera (A-F) based on a number of biological, chemical, immunological and structural criteria which include hemagglutination properties of rat and rhesus monkey erythrocytes, DNA homology, restriction enzyme cleavage patterns, percentage G+C content and oncogenicity; Straus, supra; Horwitz, supra.
Adenoviruses are attractive targets for the delivery and expression of heterologous genes. Adenoviruses are able to infect a wide variety of cells (dividing and non-dividing), and are extremely efficient in introducing their DNA into infected host cells. Adenoviruses have not been found to be associated with severe human pathology in immuno-competent individuals. The viruses can be produced at high virus titers in large quantities. The adenovirus genome is very well characterized, consisting of a linear double-stranded DNA molecule of approximately 30,000-45,000 base pairs (Adenovirus serotype 5 (“Ad5”), for instance, is ˜36,000 base pairs). Furthermore, despite the existence of several distinct serotypes, there is some general conservation found amongst the various serotypes.
The safety of adenoviruses as gene delivery vehicles is enhanced by rendering the viruses replication-defective through deletion/modification of the essential early-region 1 (“E1”) of the viral genomes, rendering the viruses devoid (or essentially devoid) of E1 activity and, thus, incapable of replication in the intended host/vaccinee; see, e.g., Brody et al, 1994 Ann N Y Acad Sci., 716:90-101. Deletion of adenoviral genes other than E1 (e.g., in E2, E3 and/or E4), furthermore, creates adenoviral vectors with greater capacity for heterologous gene inclusion. Presently, two well-characterized adenovirus serotypes of subgroup C, serotypes 5 (“Ad5”) and 2 (“Ad2”) form the basis of the most widely used gene delivery vectors.
One concern surrounding the use of adenovectors relates to any cellular and humoral immune response elicited by the virus (Chirmule et al., 1999 Gene Ther. 6:1574-1583). Although an immune response associated with the initial administration of a vector may be advantageous (Zhang et al., 2001 Mol. Ther. 3:697-707), the generation of systemic levels of adenovirus-specific neutralizing antibody may cause poor transduction when the vectors are readministered (booster immunizations; Kass-Eisler et al., 1996 Gene Ther. 3:154-162; Chirmule et al., 1999 J. Immunol. 163:448-455). The scientific literature and data from our own epidemiological studies suggest that most North Americans have anti-Ad5 neutralizing antibody titers, and about one third have relatively high titers (>200). Other parts of the world typically exhibit higher frequencies and levels of anti-Ad5 antibodies. Serospecific antibodies to these and other adenoviral serotypes resulting from such natural adenovirus infections in humans may affect the extent of response to the administration of heterologous polypeptides by adenovectors; Chirmule et al., 1999 Gene Ther. 6:1574-1583.
The instant invention offers vector compositions and methods for evading such host immunity.
The present invention relates to novel methods and compositions for improving the efficiency of adenoviral vectors in the delivery and expression of heterologous polypeptides. Adenoviral infection is relatively common in the general population, and a large percentage of people have neutralizing antibodies to the more prevalent adenoviral serotypes largely found in group C. Such pre-existing anti-adenoviral immunity can dampen or possibly abrogate the effectiveness of these viruses for the delivery and expression of heterologous proteins or antigens. The methods taught herein function to offset pre-existing immunity through the delivery and expression of heterologous polypeptides by a cocktail of at least two adenoviral serotypes. Utilizing at least two adenoviral serotypes in accordance with the methods and compositions disclosed herein has been found to increase the effectiveness of adenoviral administration. Adenoviral vectors of utility in the elicitation of an immune response against Human Immunodeficiency Virus (“HIV”) are also disclosed herein.
Applicants disclose herein novel methods and compositions for circumventing pre-existing anti-adenoviral immunity through administration of desired nucleic acid encoding a polypeptide(s) of interest via at least two adenoviral serotypes. This method is based on results of experiments conducted by Applicants employing serotypes of high homology and same group classification, contemporaneously, in the delivery and expression of nucleic acid of interest, and the favorable comparison of such delivery methodology to single serotype administrations utilizing the individual serotypes of the contemporaneous administration.
Administration of a nucleic acid of interest by at least two adenoviral serotypes proved effective in both evading pre-existing host immunity and effectuating the delivery and expression of a polypeptide of interest. The expression effected was sufficient to elicit a host immune response to the expressed polypeptide that was comparable to that effectuated by single serotype administration where pre-existing immunity did not present a challenge. Pre-existing immunity did not have any apparent detrimental effect on the induced immunity. In contrast, pre-existing immunity had a measurable impact on single serotype administration in situations where the serotype utilized was that to which pre-existing immunity was directed towards. Importantly, the cellular immune response was found to be comparable to that of the individual serotype administration that was not challenged by pre-existing immunity.
In accordance with these and other findings disclosed herein, Applicants submit that the disclosed methods and vector compositions should improve the breadth of patient coverage in gene therapy and/or vaccination protocols by overcoming potential pre-existing immunity to single serotype delivery. Consequently, the disclosed methods and compositions form a viable prospect for mass administration in the face of pre-existing immunity, even to the more prevalent (group C) adenoviral serotypes.
The present invention, therefore, relates to methods for effecting the delivery and expression of heterologous nucleic acid encoding a polypeptide(s) of interest, which comprises contemporaneously administering purified replication-defective adenovirus particles of at least two different serotypes, wherein said replication-defective adenovirus particles comprise heterologous nucleic acid encoding at least one common polypeptide. The polypeptide can be any protein or antigen which one desires to have expressed in a particular cell, tissue, or subject of interest. Administration can be either within the same composition or in separate formulations administered contemporaneously; “contemporaneous” as defined herein meaning within the same period of time. More specifically, contemporaneous administration refers to the administration of viral particles of alternative serotypes either simultaneously (whether in the same or separate formulations) or with some period of time between the administrations of the two or more different serotypes. This period of time can be of any duration, generally extending from simultaneous administration to a period of eighteen (“18”) weeks between the administrations. Preferably, the period of time between the administrations does not exceed a period of more than 18 weeks. More preferably, the period of time between administrations is significantly less than 18 weeks. Most preferably, the period of time between administrations is, in an increasing order of preference, less than four weeks, less than two weeks, less than one week, less than two days, less than one day, less than one hour, within five minutes (“simultaneous” administration). The result sought by contemporaneous administration is not that of a “prime-boost” effect but rather the effect of a single administration (albeit alternative administrations can be present), whether that administration be in the form of a prime (or primes employing the at least two serotypes), in the form of a boost (employing the at least two serotypes), or involving prime and boost administrations (the administrations of which independently both comprise the at least two serotypes). The present invention contemplates as welt the contemporaneous administration of at least two adenoviral serotypes encoding at least one common polypeptide in a sole administration not dependent on a prime/boost regimen.
The present invention also relates to compositions comprising the at least two adenoviral serotypes; said at least two adenoviral serotypes comprising heterologous nucleic acid encoding at least one common polypeptide. The methods in accordance with the present invention utilize (and compositions in accordance with the present invention comprise) purified replication-defective adenovirus particles of at least two different serotypes. There are over 100 distinct adenoviral serotypes identified to date that can be utilized in the methods/compositions of the present invention; 51 of which are of human origin and numerous that infect various different species, including various mammalian species; Straus, 1984, In The Adenoviruses, ed. H. Ginsberg, pps. 451-498, New York:Plenus Press; Hierholzer et al., 1988 J. Infect. Dis. 158:804-813; Schnurr and Dondero, 1993, Intervirology; 36:79-83; De Jong et al., 1999 J Clin Microbiol., 37:3940-5; and Wadell et al., 1999 In Manual of Clinical Microbiology, 7th ed. American Society for Microbiology, pp. 970-982. One of skill in the art can readily identify and develop adenoviruses of alternative and distinct serotype (including, but not limited to, the foregoing) for purposes consistent with the methods and compositions of the present invention. Those of skill in the art are readily familiar with the various adenoviral serotypes including, but not limited to, (1) the numerous serotypes of subgenera A-F discussed above, (2) unclassified adenovirus serotypes, (3) non-human serotypes (including but not limited to primate adenoviruses (see, e.g., Fitzgerald et al., 2003 J. Immunol. 170(3)1416-1422; Xiang et al., 2002 J. Virol. 76(6):2667-2675)), and equivalents, modifications, or derivatives of the foregoing. Adenoviruses can readily be obtained from the American Type Culture Collection (“ATCC”) or other publicly available/private source; and adenoviral sequences can be discerned from both the published literature and widely accessible public databases, where not obtained elsewhere.
The specific combination of serotypes suitable for use in the methods and compositions disclosed herein is limitless. There are numerous means by which one can choose a candidate combination of serotypes. One means by which to evaluate a candidate pairing of serotypes is to evaluate the seroprevalence of the vectors in combination (i.e., determine whether the population tends to be more/less/equally infected by all of the serotypes of the combination). Preferably, the effective neutralizing antisera titer to the combination of serotype components is lower than that exhibited to an individual serotype (particularly to a serotype(s) of real interest) or, in the alternative, the percentage of individuals with serotype-specific neutralizing antisera titers to all the serotype components is less than that with titers to an individual serotype tested (again, particularly to the serotype(s) of real interest). The effective neutralizing antisera titer against a candidate composition (i.e., the combination of serotype components) is the lower of the titers tested since that component of the vector will therefore be more potent. For purposes of comparison, arbitrary ranges can, but need not be, established as a qualitative reference for the potency of a determined serum towards specific serotypes (for example, ranges used herein for Ad5 were as follows: very low or undetectable [<18], low [18-200], medium [201-1000], and high [>1000]).
Evaluation of serotype-specific neutralizing antisera as a means of selecting an appropriate serotype adenovector is well understood and appreciated in the art, and the practice thereof is well within the realm of one of ordinary skill in the art; Aste-Amézaga, 2004 Hum. Gene Ther. 15:293-304; Piedra et al., 1998 Pediatrics 101(6): 1013-1019; Sanchez et al., 2001 J. Med. Virol. 65:710-718; Sprangers et al., 2003 J. Clin. Microbiol. 41(11):5046-5052; and Nwanegbo et al., 2004 Clin. Diagn. Lab. Immunol. 11(2)351-357. Additionally, several methods are available for determining type-specific antibodies to adenovirus (Ad) serotypes. Several different assay formats can be used such as, for example, end point dilution assays, or any available assays designed to evaluate gene expression. The basic principle behind such assays is to ascertain the specificity/existence of any preexisting antisera in the subject population. In the present studies, serum neutralization studies were utilized to evaluate the preexisting antisera of the candidate population; see Example 1. Serum neutralization assays generally involve incubating serum (from a candidate(s)) along with virus of the serotype of interest and cells to ascertain whether the serum contains antibodies specific for the virus sufficient to inhibit infection of the cells. Infection can be detected by a number of methods, the most frequently utilized being cell viability or transgene expression; Sprangers et al., supra.
As a substitute for, or a complement to, the various assays discussed above, various epidemiological studies are available for reference as well for use in determining the prevalence of neutralizing antibodies to a specific serotype(s) in a given population; see, e.g., Nwanegbo et al. supra. As one of ordinary skill in the art will appreciate, the present invention certainly contemplates as one embodiment hereof administration of a serotype of adenovirus which is appreciated in the art as prevalent/moderately prevalent in a given population with one appreciated in the art as not as prevalent in the population, without the obligation of undergoing a specific study on an individualized basis as discussed above. Combinations of adenovirus for contemporaneous administration can, therefore, be constructed based on existing knowledge.
One of skill in the art can envision the various possibilities made possible by the present disclosure. If one serotype is known or found not to be prevalent in a population of individuals, that serotype can be utilized with one or more that is a bit more prevalent to support the administration in the event that neutralizing antisera to the prevalent adenovirus poses a threat/challenge. In an alternative scenario, rare serotypes can be administered contemporaneously. Additionally, as evidenced herein, two or more relatively prevalent serotypes can be administered contemporaneously, particularly where the effective neutralizing antisera titer to the combination of serotype components is lower than that exhibited to an individual serotype (particularly to a serotype(s) of real interest) or, in the alternative, the percentage of individuals with serotype-specific neutralizing antisera titers to the combination of serotype components is less than that with titers to an individual serotype tested (again, particularly to the serotype(s) of real interest). Accordingly, the present invention encompasses and is exemplified herein by contemporaneous administration of adenovirus serotypes 5 and 6, both encoding at least one common polypeptide of interest. Adenovirus serotypes 5 and 6 are well known in the art (American Type Culture Collection (“ATCC”) Deposit Nos. VR-5 and VR-6, respectively, and sequences therefore have been published; see Chroboczek et al., 1992 J. Virol. 186:280, and PCT/US02/32512, published Apr. 17, 2003, respectively). Despite the relatively high percentage of individuals exhibiting neutralizing antisera titers to both serotypes on a population-wide basis, Applicants found that the percentage of individuals with relatively high titers of neutralizing antibodies to both was significantly lower. Furthermore, while employing the two relatively prevalent group C adenoviral serotypes as vectors for the delivery and expression of a heterologous polypeptide, Applicants discovered that pre-existing immunity did not have any apparent detrimental impact on their contemporaneous delivery. By contrast, pre-existing immunity had a measurable impact on administration using one of the serotypes for which pre-existing immunity was present. The cocktail was, furthermore, effectively able to express sufficient amounts of the polypeptide to elicit a cellular immune response which was comparable to that of the individual serotype of the cocktail that was not effected by pre-existing immunity.
Another embodiment of the present invention involves the combination/contemporaneous administration of human serotypes of adenovirus with serotypes that naturally infect other species. For purposes of exemplification, this could entail administering, contemporaneously, a human adenovirus and an adenovirus that naturally infects primates, including but not limited to chimpanzees.
One of skill in the art can readily identify adenoviruses of alternative and distinct serotype (e.g., the various serotypes found in subgenera A-F discussed above; including but not limited to those on deposit with widely accessible public depositories such as the American Type Culture Collection (“ATCC”) and those for whom the sequence is known and/or published in the scientific literature and widely available public sequence databases). As is taught herein, any combination of these adenoviral serotypes is suitable for use in the present invention, provided that neutralizing antisera does not present a hindrance to administration of a desired combination of serotypes. As stated, this can be determined very readily by one of skill in the pertinent art from published literature concerning the relative prevalence of the various serotypes in specific populations, from actual experiments conducted, or from the various assays discussed above which are available to identify the existence of/quantify immunity to the serotype/classification group of interest.
Adenoviral serotypes administered via the methods and compositions of the present invention should be replication-impaired in the intended host; unless the replication thereof in the intended host is determined not to pose a safety issue. Preferably, the vectors are at least partially deleted/mutated in E1 such that any resultant virus is devoid (or essentially devoid) of E1 activity, rendering the vector incapable of replication in the intended host. Preferably, the E1 region is completely deleted or inactivated. Specific embodiments of the present invention employ adenoviral vectors as described in PCT/US01/28861, published Mar. 21, 2002. Said vectors are at least partially deleted in E1 and comprise several adenoviral packaging repeats (i.e., the E1 deletion does not start until approximately base pairs 450-458, with base pair numbers assigned corresponding to a wildtype Ad5 sequence). The adenoviruses may contain additional deletions in E3, and other early regions, albeit in certain situations where E2 and/or E4 is deleted, E2 and/or E4 complementing cell lines may be required to generate recombinant, replication-defective adenoviral vectors. Vectors devoid of adenoviral protein-coding regions (“gutted vectors”) are also feasible for use herein. Such vectors typically require the presence of helper virus for the propagation and development thereof.
Adenoviral vectors can be constructed using well known techniques, such as those reviewed in Graham & Prevec, 1991 In Methods in Molecular Biology: Gene Transfer and Expression Protocols, (Ed. Murray, E. J.), p. 109; and Hitt et al., 1997 “Human Adenovirus Vectors for Gene Transfer into Mammalian Cells” Advances in Pharmacology 40:137-206. Example 2 details the construction of several adenoviral vector constructs suitable for use herein.
E1 -complementing cell lines used for the propagation and rescue of recombinant adenovirus should provide elements essential for the viruses to replicate, whether the elements are encoded in the cell's genetic material or provided in trans. It is, furthermore, preferable that the E1-complementing cell line and the vector not contain overlapping elements which could enable homologous recombination between the nucleic acid of the vector and the nucleic acid of the cell line potentially leading to replication competent virus (or replication competent adenovirus “RCA”). Often, propagation cells are human cells derived from the retina or kidney, although any cell line capable of expressing the appropriate E1 and any other critical deleted region(s) can be utilized to generate adenovirus suitable for use in the methods of the present invention. Embryonal cells such as amniocytes have been shown to be particularly suited for the generation of E1 complementing cell lines. Several cell lines are available and include but are not limited to the known cell lines PER.C6® (ECACC deposit number 96022940), 911, 293, and E1 A549. PER.C6® cell lines are described in WO 97/00326 (published Jan. 3, 1997) and issued U.S. Pat. No. 6,033,908. PER.C6® is a primary human retinoblast cell line transduced with an E1 gene segment that complements the production of replication deficient (FG) adenovirus, but is designed to prevent generation of replication competent adenovirus by homologous recombination. 293 cells are described in Graham et al., 1977 J. Gen. Virol. 36:59-72. For the propagation and rescue of non-group C adenoviral vectors, a cell line expressing an E1 region which is complementary to the E1 region deleted in the virus being propagated can be utilized. Alternatively, a cell line expressing regions of E1 and E4 derived from the same serotype can be employed; see, e.g., U.S. Pat. No. 6,270,996. Another alternative would be to propagate non-group C adenovirus in available E1-expressing cell lines (e.g., PER.C6®, A549 or 293). This latter method involves the incorporation of a critical E4 region into the adenovirus to be propagated. The critical E4 region is native to a virus of the same or highly similar serotype as that of the E1 gene product(s) (particularly the E1B 55K region) of the complementing cell line, and comprises typically, at a minimum, E4 open reading frame 6 (“ORF6”)); see, PCT/US2003/026145, published Mar. 4, 2004. One of skill in the art can readily appreciate and carry out numerous other methods suitable for the production of recombinant, replication-defective adenoviruses suitable for use in the methods of the present invention. Following viral production in whatever means employed, viruses may be purified, formulated and stored prior to host administration.
The methods and compositions described herein are well suited to effectuate the expression of heterologous polypeptides, especially in situations where pre-existing immunity prevents administration or readministration of at least one of the adenoviral serotypes employed. Accordingly, specific embodiments of the present invention comprise methods for effecting the delivery and expression of heterologous nucleic acid encoding a polypeptide(s) of interest, which comprises contemporaneously administering purified replication-defective adenovirus particles of at least two different serotypes, wherein said replication-defective adenovirus particles comprise heterologous nucleic acid encoding at least one common polypeptide. Additional embodiments of the present invention are compositions comprising purified replication-defective adenovirus particles of at least two different serotypes, wherein said replication-defective adenovirus particles comprise heterologous nucleic acid encoding at least one common polypeptide. The expressed nucleic acid can be DNA and/or RNA, and can be double or single stranded. The nucleic acid can be inserted in an E1 parallel (transcribed 5′ to 3′ relative to the vector backbone) or anti-parallel (transcribed 3′ to 5′ relative to the vector backbone) orientation. The nucleic acid can be codon-optimized for expression in the desired host (e.g., a mammalian host). The heterologous nucleic acid can be in the form of an expression cassette. A gene expression cassette can contain (a) nucleic acid encoding a protein or antigen of interest; (b) a heterologous promoter operatively linked to the nucleic acid encoding the protein/antigen; and (c) a transcription termination signal.
In specific embodiments, the heterologous promoter is recognized by a eukaryotic RNA polymerase. One example of a promoter suitable for use in the present invention is the immediate early human cytomegalovirus promoter (Chapman et al., 1991 Nucl. Acids Res. 19:3979-3986). Further examples of promoters that can be used in the present invention are the strong immunoglobulin promoter, the EFI alpha promoter, the murine CMV promoter, the Rous Sarcoma Virus promoter, the SV40 early/late promoters and the beta actin promoter, albeit those of skill in the art can appreciate that any promoter capable of effecting expression of the heterologous nucleic acid in the intended host can be used in accordance with the methods of the present invention. The promoter may comprise a regulatable sequence such as the Tet operator sequence. Sequences such as these that offer the potential for regulation of transcription and expression are useful in circumstances where repression/modulation of gene transcription is sought. The adenoviral gene expression cassette may comprise a transcription termination sequence; specific embodiments of which are the bovine growth hormone termination/polyadenylation signal (bGHpA) or the short synthetic polyA signal (SPA) of 50 nucleotides in length defined as follows: AATAAAAGATCTTTATTTTCATTAGATCTGTGTGTTGGTTTTTTGTGTG (SEQ ID NO: 1). A leader or signal peptide may also be incorporated into the transgene. In specific embodiments, the leader is derived from the tissue-specific plasminogen activator protein, tPA.
Heterologous nucleic acids of interest typically encode immunogenic and/or therapeutic proteins. Preferred therapeutic proteins are those which elicit some measurable therapeutic benefit in the individual host upon administration. Preferred immunogenic proteins are those proteins which are capable of eliciting a protective and/or beneficial immune response in an individual. A specific embodiment of the instant invention, illustrated herein, is the delivery of nucleic acid encoding representative immunogenic proteins (HIV Gag, Nef and/or Pol) by the methods and compositions disclosed, albeit any gene encoding a therapeutic or immunogenic protein can be used in accordance with the methods disclosed herein and form important embodiments hereof. The methods and compositions disclosed in the present invention do not hinge upon any specific heterologous nucleic acid. Accordingly, the methods and compositions of the instant invention can be used to effectuate the delivery of any polypeptide whose presence/function brings about a desired effect in a given host, particularly a therapeutic/immunogenic effect useful in the treatment/alteration/modification of various conditions associated with, caused by, effected by (positively or negatively), exacerbated by, or modified by the presence or absence of a particular nucleic acid, protein, antigen, fragment, or activity associated with any of the foregoing.
One aspect of the present invention, as indicated above, relates to methods and compositions employing adenoviral vectors carrying heterologous nucleic acid encoding an HIV antigen(s)/protein(s). Human Immunodeficiency Virus (“HIV”) is the etiological agent of acquired human immune deficiency syndrome (AIDS) and related disorders. HIV is an RNA virus of the Retroviridae family and exhibits the 5′LTR-gag-pol-env-LTR 3′ organization of all retroviruses. The integrated form of HIV, known as the provirus, is approximately 9.8 Kb in length. Each end of the viral genome contains flanking sequences known as long terminal repeats (LTRs).
Heterologous nucleic acid encoding an HIV antigen/protein may be derived from any HIV strain, including but not limited to HIV-1 and HIV-2, strains A, B, C, D, E, F, G, H, I, O, IIIB, LAV, SF2, CM235, and US4; see, e.g., Myers et al., eds. “Human Retroviruses and AIDS: 1995 (Los Alamos National Laboratory, Los Alamos N.M. 97545). Another HIV strain suitable for use in the methods disclosed herein is HIV-1 strain CAM-1; Myers et al, eds. “Human Retroviruses and AIDS”: 1995, IIA3-IIA19. This gene closely resembles the consensus amino acid sequence for the clade B (North American/European) sequence. HIV gene sequence(s) may be based on various clades of HIV-1; specific examples of which are Clades A, B, and C. Sequences for genes of many HIV strains are publicly available from GenBank and primary, field isolates of HIV are available from the National Institute of Allergy and Infectious Diseases (NIAID) which has contracted with Quality Biological (Gaithersburg, Md.) to make these strains available. Strains are also available from the World Health Organization (WHO), Geneva Switzerland.
HIV genes encode at least nine proteins and are divided into three classes; the major structural proteins (Gag, Pol, and Env), the regulatory proteins (Tat and Rev); and the accessory proteins (Vpu, Vpr, Vif and Nef). The gag gene encodes a 55-kilodalton (kDa) precursor protein (p55) which is expressed from the unspliced viral mRNA and is proteolytically processed by the HIV protease, a product of the pol gene. The mature p55 protein products are p17 (matrix), p24 (capsid), p9 (nucleocapsid) and p6. The pol gene encodes proteins necessary for virus replication—protease (Pro, P10), reverse transcriptase (RT, P50), integrase (IN, p31) and RNAse H (RNAse, p15) activities. These viral proteins are expressed as a Gag or Gag-Pol fusion protein which is generated by a ribosomal frame shift. The 55 kDa gag and 160 kDa gagpol precursor proteins are then proteolytically processed by the virally encoded protease into their mature products. The nef gene encodes an early accessory HIV protein (Nef) which has been shown to possess several activities such as down regulating CD4 expression, disturbing T-cell activation and stimulating HIV infectivity. The env gene encodes the viral envelope glycoprotein that is translated as a 160-kilodalton (kDa) precursor (gp160) and then cleaved by a cellular protease to yield the external 120-kDa envelope glycoprotein (gp120) and the transmembrane 41-kDa envelope glycoprotein (gp41). Gp120 and gp41 remain associated and are displayed on the viral particles and the surface of HIV-infected cells. The tat gene encodes a long form and a short form of the Tat protein, a RNA binding protein which is a transcriptional transactivator essential for HIV replication. The rev gene encodes the 13 kDa Rev protein, a RNA binding protein. The Rev protein binds to a region of the viral RNA termed the Rev response element (RRE). The Rev protein promotes transfer of unspliced viral RNA from the nucleus to the cytoplasm. The Rev protein is required for HIV late gene expression and in turn, HIV replication.
Nucleic acid encoding any HIV antigen may be utilized in the methods and compositions of the present invention (specific examples of which include but are not limited to the aforementioned genes, nucleic acid encoding active and/or immunogenic fragments thereof, and/or modifications/derivatives of any of the foregoing). The present invention contemplates as well the various codon-optimized forms of nucleic acid encoding HIV antigens, including codon-optimized HIV gag (including but by no means limited to p55 versions of codon-optimized full length (“FL”) Gag and tPA-Gag fusion proteins), HIV pol, HIV nef, HIV env, HIV tat, HIV rev, and modifications/derivatives of immunological relevance. Embodiments exemplified herein employ nucleic acid encoding codon-optimized Nef antigens; codon-optimized p55 Gag antigens; and codon-optimized Pol antigens. Codon-optimized HIV-1 gag genes are disclosed in PCT International Application PCT/US00/18332, published Jan. 11, 2001 (WO 01/02607). Codon-optimized HIV-1 env genes are disclosed in PCT International Applications PCT/US97/02294 and PCT/US97/10517, published Aug. 28, 1997 (WO 97/31115) and Dec. 24, 1997 (WO 97/48370), respectively. Codon-optimized HIV-1 pol genes are disclosed in U.S. application Ser. No. 09/745,221, filed Dec. 21, 2000 and PCT International Application PCT/US00/34724, also filed Dec. 21, 2000. Codon-optimized HIV-1 nef genes are disclosed in U.S. application Ser. No. 09/738,782, filed Dec. 15, 2000 and PCT International Application PCT/US00/34162, also filed Dec. 15, 2000. It is well within the purview of the skilled artisan to choose an appropriate nucleotide sequence including but not limited to those cited above which encodes a specific HIV antigen, or immunologically relevant portion or, modification/derivative thereof. “Immunologically relevant” or “antigenic” as defined herein means (1) with regard to a viral antigen, that the protein is capable, upon administration, of eliciting a measurable immune response within an individual sufficient to retard the propagation and/or spread of the virus and/or to reduce/contain viral load within the individual; or (2) with regards to a nucleotide sequence, that the sequence is capable of encoding for a protein capable of the above. One of skill in the art can, furthermore, appreciate that any nucleic acid encoding for a protein, antigen, derivative or fragment capable of effectuating a desired result (sequences that may or may not be codon-optimized) is of use in the methods and compositions of the instant invention.
A codon-optimized gag gene that can be utilized in the methods and compositions of the present invention is that disclosed in PCT/US00/18332, published Jan. 11, 2001 (see
Open reading frames for various synthetic pol genes contemplated herein and disclosed in PCT/US00/34724 comprise coding sequences for reverse transcriptase (or RT which consists of a polymerase and RNase H activity) and integrase (IN). The protein sequence is based on that of Hxb2r, a clonal isolate of IIIB; this sequence has been shown to be closest to the consensus clade B sequence with only 16 nonidentical residues out of 848 (Korber, et al., 1998, Human retroviruses and AIDS, Los Alamos National Laboratory, Los Alamos, N.M.).
A particular embodiment of this portion of the invention comprises methods and compositions comprising codon optimized nucleotide sequences which encode wt-pol constructs (herein, “wt-pol” or “wt-pol (codon optimized))” wherein sequences encoding the protease (PR) activity are deleted, leaving codon optimized “wild type” sequences which encode RT (reverse transcriptase and RNase H activity) and IN integrase activity. A DNA molecule which encodes this protein is disclosed herein as SEQ ID NO:3 (
Alternative specific embodiments relate to methods and compositions utilizing adenoviral vector constructs which comprise codon optimized IFV-1 pol wherein, in addition to deletion of the portion of the wild type sequence encoding the protease activity, a combination of active site residue mutations are introduced which are deleterious to IFV-1 pol (RT-RH-IN) activity of the expressed protein. Therefore, the present invention relates to methods and compositions employing an adenoviral construct comprising HIV-1 pol wherein the construct is devoid of sequences encoding any PR activity, as well as containing a mutation(s) which at least partially, and preferably substantially, abolishes RT, RNase and/or IN activity. One type of HIV-1 pol mutant which is part and parcel of an adenoviral vector construct of use in the methods and compositions disclosed herein may include but is not limited to a mutated nucleic acid molecule comprising at least one nucleotide substitution which results in a point mutation which effectively alters an active site within the RT, RNase and/or IN regions of the expressed protein, resulting in at least substantially decreased enzymatic activity for the RT, RNase H and/or IN functions of HIV-1 Pol. In a specific embodiment of this portion of the invention, a HIV-1 DNA pol construct contains a mutation (or mutations) within the Pol coding region which effectively abolishes RT, RNase H and IN activity. A specific HIV-1 pol-containing construct contains at least one point mutation which alters the active site of the RT, RNase H and IN domains of Pol, such that each activity is at least substantially abolished. Such a HIV-1 Pol mutant will most likely comprise at least one point mutation in or around each catalytic domain responsible for RT, RNase H and IN activity, respectfully. To this end, specific embodiments relate to methods and compositions utilizing HIV-1 pol wherein the encoding nucleic acid comprises nine codon substitution mutations which result in an inactivated Pol protein (IA Pol: SEQ ID NO: 6,
It is preferred that point mutations be incorporated into the IApol mutant adenoviral vector constructs of the present invention so as to lessen the possibility of altering epitopes in and around the active site(s) of HIV-1 Pol. To this end, SEQ ID NO: 5 (
To produce adenoviral constructs comprising IA-pol for use in the vectors, methods and compositions of the present invention, inactivation of the enzymatic functions was achieved by replacing a total of nine active site residues from the enzyme subunits with alanine side-chains. As shown in Table 1, all residues that comprise the catalytic triad of the polymerase, namely Asp112, Asp187, and Asp188, were substituted with alanine (Ala) residues (Larder, et al., Nature 1987, 327: 716-717; Larder, et al., 1989, Proc. Natl. Acad. Sci. 1989, 86: 4803-4807). Three additional mutations were introduced at Asp445, Glu480 and Asp500 to abolish RNase H activity (Asp551 was left unchanged in this IA Pol construct), with each residue being substituted for an Ala residue, respectively (Davies, et al., 1991, Science 252:, 88-95; Schatz, et al., 1989, FEBS Lett. 257: 311-314; Mizrahi, et al., 1990, Nucl. Acids. Res. 18: pp. 5359-5353). HIV pol integrase function was abolished through three mutations at Asp626, Asp678 and Glu714. Again, each of these residues was substituted with an Ala residue (Wiskerchen, et al., 1995, J. Virol. 69: 376-386; Leavitt, et al., 1993, J. Biol. Chem. 268: 2113-2119). Amino acid residue Pro3 of SEQ ID NO: 6 marks the start of the RT gene. The complete amino acid sequence of IA-Pol is disclosed herein as SEQ ID NO: 6 and shown in
As noted above, it will be understood that any combination of the mutations disclosed above may be suitable and therefore be utilized in adenoviral HIV constructs, methods and compositions of the present invention, either when administered alone, with other heterologous genes, in a combined modality regime and/or as part of a prime-boost regimen. For example, it may be possible to mutate only 2 of the 3 residues within the respective reverse transcriptase, RNase H, and integrase coding regions while still abolishing these enzymatic activities.
Another aspect of this portion of the invention are methods, vectors and compositions employing adenoviral vector constructs comprising codon optimized HIV-1 Pol comprising a eukaryotic trafficking signal peptide or a leader peptide such as is found in highly expressed mammalian proteins such as immunoglobulin leader peptides. Any functional leader peptide may be tested for efficacy. The respective DNA may be modified by known recombinant DNA methodology. In the alternative, as noted above, a nucleotide sequence which encodes a leader/signal peptide may be inserted into a DNA vector housing the open reading frame for the Pol protein of interest. Regardless of the cloning strategy, the end result is a vector construct which comprises vector components for effective gene expression in conjunction with nucleotide sequences which encode a modified HIV-1 Pol protein of interest, including but not limited to a HIV-1 Pol protein which contains a leader peptide.
The design of gene sequences disclosed herein incorporates the use of human preferred (“humanized”) codons for each amino acid residue in the sequence in order to maximize in vivo mammalian expression (Lathe, 1985, J. Mol. Biol. 183:1-12). As can be discerned by inspecting the codon usage in SEQ ID NOs: 3 and 5, the following codon usage for mammalian optimization is preferred: Met (ATG), Gly (GGC), Lys (AAG), Trp (TGG), Ser (TCC), Arg (AGG), Val (GTG), Pro (CCC), Thr (ACC), Glu (GAG); Leu (CTG), His (CAC), Ile (ATC), Asn (AAC), Cys (TGC), Ala (GCC), Gln (CAG), Phe (TTC) and Tyr (TAC). For an additional discussion relating to mammalian (human) codon optimization, see WO 97/31115 (PCT/US97/02294). It is intended that the skilled artisan may use alternative versions of codon optimization or may omit this step when generating HIV vaccine constructs within the scope of the present invention. Therefore, the present invention also relates to vectors, methods and compositions comprising/utilizing non-codon optimized or partially codon optimized versions of nucleic acid molecules and associated recombinant adenoviral HIV constructs which encode the various wild type and modified forms of the HIV proteins. However, codon optimization of these constructs constitutes a preferred embodiment of this invention.
Codon optimized versions of HIV-1 nef and HIV-1 nef modifications of use in specific embodiments of the present invention can be found in U.S. application Ser. No. 09/738,782, filed Dec. 15, 2000 and PCT International Application PCT/US00/34162, also filed Dec. 15, 2000. Particular codon optimized nef and nef modifications relate to nucleic acid encoding HIV-1 Nef from the HIV-1 jrfl isolate wherein the codons are optimized for expression in a mammalian system such as a human. A DNA molecule which encodes this protein is disclosed herein as SEQ ID NO: 7 (
HIV-1 Nef is a 216 amino acid cytosolic protein which associates with the inner surface of the host cell plasma membrane through myristylation of Gly-2 (Franchini et al., 1986, Virology 155: 593-599). While not all possible Nef functions have been elucidated, it has become clear that correct trafficking of Nef to the inner plasma membrane promotes viral replication by altering the host intracellular environment to facilitate the early phase of the HIV-1 life cycle and by increasing the infectivity of progeny viral particles. In one aspect of the invention, the methods, vectors and compositions of the present invention employ an adenoviral vector(s) comprising codon-optimized nef sequence modified to contain a nucleotide sequence which encodes a heterologous leader peptide such that the amino terminal region of the expressed protein will contain the leader peptide. The diversity of function that typifies eukaryotic cells depends upon the structural differentiation of their membrane boundaries. To generate and maintain these structures, proteins must be transported from their site of synthesis in the endoplasmic reticulum to predetermined destinations throughout the cell. This requires that the trafficking proteins display sorting signals that are recognized by the molecular machinery responsible for route selection located at the access points to the main trafficking pathways. Sorting decisions for most proteins need to be made only once as they traverse their biosynthetic pathways since their final destination, the cellular location at which they perform their function, becomes their permanent residence. Maintenance of intracellular integrity depends in part on the selective sorting and accurate transport of proteins to their correct destinations. Defined sequence motifs exist in proteins which can act as ‘address labels’. A number of sorting signals have been found associated with the cytoplasmic domains of membrane proteins. An effective induction of CTL responses often required sustained, high level endogenous expression of an antigen. As membrane-association via myristylation is an essential requirement for most of Nef's function, mutants lacking myristylation, by glycine-to-alanine change, change of the dileucine motif and/or by substitution with a leader sequence, will be functionally defective, and therefore will have improved safety profile compared to wild-type Nef for use as an HIV-1 vaccine component.
In specific embodiments, therefore, the nucleotide sequence is modified to include a leader or signal peptide of interest. This may be accomplished by known recombinant DNA methodology. In the alternative, as noted above, insertion of a nucleotide sequence may be inserted into a DNA vector housing the open reading frame for the Nef protein of interest.
It has been shown that myristylation of Gly-2 in conjunction with a dileucine motif in the carboxy region of the protein is essential for Nef-induced down regulation of CD4 (Aiken et al., 1994, Cell 76: 853-864) via endocytosis. It has also been shown that Nef expression promotes down regulation of MHCI (Schwartz et al., 1996, Nature Medicine 2(3): 338-342) via endocytosis. The present invention contemplates adenoviral vectors which comprise sequence encoding a modified Nef protein altered in trafficking and/or functional properties and the use thereof in the methods and compositions of the present invention. The modifications introduced into the adenoviral vector HIV constructs of the present invention include but are not limited to additions, deletions or substitutions to the nef open reading frame which results in the expression of a modified Nef protein which includes an amino terminal leader peptide, modification or deletion of the amino terminal myristylation site, and modification or deletion of the dileucine motif within the Nef protein and which alter function within the infected host cell.
A recombinant adenoviral construct of use in accordance with the methods and compositions disclosed herein can comprise sequence encoding optimized HIV-1 Nef with modifications at the amino terminal myristylation site (Gly-2 to Ala-2) and substitution of the Leu-174-Leu-175 dileucine motif to Ala-174-Ala-175. This open reading frame is herein described as opt nef (G2A,LLAA) and is disclosed as SEQ ID NO: 9, which comprises an initiating methionine residue at nucleotides 12-14 and a “TAA” stop codon from nucleotides 660-662. The nucleotide sequence of this codon optimized version of HIV-1 jrfl nef gene with the above mentioned modifications is disclosed herein as SEQ ID NO: 9;
Another recombinant adenoviral construct of use in accordance with the methods and compositions disclosed herein can comprise sequence encoding optimized HIV-1 Nef with modifications at the amino terminal myristylation site (Gly-2 to Ala-2). This open reading frame is herein described as opt nef (G2A) and is disclosed as SEQ ID NO: 13, which comprises an initiating methionine residue at nucleotides 12-14 and a “TAA” stop codon from nucleotides 660-662. The nucleotide sequence of this codon optimized version of HIV-1 jrfl nef gene with the above mentioned modification is disclosed herein as SEQ ID NO: 12;
Adenoviral vectors of use in the methods and compositions of the present invention may comprise one or more HIV genes/encoding nucleic acid. The administration of at least one (preferably, at least two) recombinant adenoviral vector(s) comprising two or more HIV genes, their derivatives, or modifications are anticipated as well as exemplified herein. Two or more HIV genes can be expressed on at least one of the recombinant adenoviral vector constructs and/or two or more HIV genes can be expressed across two or more constructs. One of skill in the art can readily appreciate that the present invention, therefore, encompasses those situations where, while only one antigen is in common amongst at least two of the vectors of different serotype, the vectors may have additional HIV genes that (1) differ, (2) are the same, (3) while not in common with that vector, are in common with another vector utilized in the disclosed methods or compositions, or (4) are derived from the same common antigen. Therefore, the present invention offers the possibility of using the methods and compositions of the present invention to evade/bypass host immunity and effectuate a multi-valent HIV gene administration, specific examples, but not limitations of which, include the administration of adenoviral vectors comprising nucleic acid sequence encoding (1) Gag and Nef polypeptides, (2) Gag and Pol polypeptides, (3) Pol and Nef polypeptides, and (4) Gag, Pol and Nef polypeptides.
Multiple genes/encoding nucleic acid may be ligated into a proper shuttle plasmid for generation of a pre-adenoviral plasmid comprising multiple open reading frames. Open reading frames for the multiple genes/encoding nucleic acid can be operatively linked to distinct promoters and transcription termination sequences. In other embodiments, the open reading frames may be operatively linked to a single promoter, with the open reading frames operatively linked by an internal ribosome entry sequence (IRES; as disclosed in WO 95/24485), or suitable alternative allowing for transcription of the multiple open reading frames to run off of a single promoter. In certain embodiments, the open reading frames may be fused together by stepwise PCR or suitable alternative methodology for fusing together two open reading frames. Various combined modality administration regimens suitable for use in the present invention are disclosed in PCT/US01/28861, published Mar. 21, 2002.
Several multi-valent vectors of this description are also disclosed herein (see, e.g., Example 2 and the corresponding Figures) and form an important aspect of the present invention. Methods of using same in eliciting cellular-mediated immune responses specific for the HIV antigens contained therein are also encompassed herein. Said vectors comprise nucleic acid encoding at least two antigens selected from the group consisting of gag, nef and/or pol antigens. The nucleic acid can be as disclosed herein or can be any modification, derivative or functional equivalent of same. Preferably, the nucleic acid sequences are codon-optimized or partially codon-optimized. Specific embodiments of the present invention are such constructs which are di/tri-cistronic (i.e., the individual antigens are under the control of distinct promoters). Specific constructs in accordance with the above disclosure are described further as adenoviral vectors comprising nucleic acid encoding (1) gag and nef; (2) gag and pol; and (3) gag, pol and nef. In one embodiment, the adenoviral serotypes are of adenoviral serotype 5 or 6. In further embodiments the adenoviral vectors are deleted in E1 and E3 to accommodate the heterologous nucleic acid. In additional embodiments, the adenoviral vectors disclosed herein have the heterologous nucleic acid present in an E1 deletion of a region which corresponds to that of nucleotides 451-3510 of adenovirus serotype 5 or nucleotides 451-3507 of adenovirus serotype 6. In specific embodiments, the adenoviral vectors comprise the nucleic acid encoding the at least two antigens under the control of at least two promoters, one driving expression of nucleic acid encoding at least one of the antigens and at least one other driving the expression of nucleic acid encoding at least one other antigen. Specific constructs disclosed herein are adenoviral vectors comprising nucleic acid encoding: (1) nef and gag under the control of two distinct promoters; (2) nef and gag under the control of the hCMV and mCMV promoters (see, e.g., Examples 2H and 2I and
Further embodiments of the present invention relate to the contemporaneous administration of more than one vector administered by the at least two serotypes. For instance, two or more serotypes both comprising nucleic acid A can be co-administered with two or more serotypes both comprising nucleic acid B. In this manner, the properties of the instant administration strategies can be exploited to administer nucleic acid that one may want, for one reason or another, across more than one vector. One example solely for purposes of exemplification and not limitation would be a scenario wherein the following vectors were administered contemporaneously: (1) Ad5 comprising nucleic acid encoding antigen A; (2) Ad5 comprising nucleic acid encoding antigen A; (3) Ad6 comprising nucleic acid encoding antigens B and C; and (4) Ad5 comprising nucleic acid encoding antigens B and C.
Regardless of the antigen/method chosen, contemporaneous administration of recombinant adenoviruses in accordance with the methods of the present invention may be the subject of a single administration or form part of a broader prime/boost-type administration regimen. Prime-boost regimens can employ different viruses (including but not limited to different viral serotypes and viruses of different origin), viral vector/protein combinations, and combinations of viral and polynucleotide administrations. In this type of scenario, an individual is first administered a priming dose of a protein/antigen/derivative/modification utilizing a certain vehicle (be that a viral vehicle, purified and/or recombinant protein, or encoding nucleic acid). Multiple primings, typically 1-4, are usually employed, although more may be used. The priming dose(s) effectively primes the immune response so that, upon subsequent identification of the protein/antigen(s) in the circulating immune system, the immune response is capable of immediately recognizing and responding to the protein/antigen(s) within the host. Following some period of time, the individual is administered a boosting dose of at least one of the previously delivered protein(s)/antigen(s), derivatives or modifications thereof (administered by viral vehicle/protein/nucleic acid). The length of time between priming and boost may typically vary from about four months to a year, albeit other time frames may be used as one of ordinary skill in the art will appreciate. The follow-up or boosting administration may also be repeated at selected time intervals. In certain embodiments, contemporaneous administration in accordance herewith can be employed for both the prime and boost administrations. A mixed modality prime and boost inoculation scheme should result in an enhanced immune response, specifically where there is pre-existing anti-vector immunity.
Selection of the alternate administration vehicle (be it viral/nucleic acid/protein) to be employed in conjunction with the methods and compositions disclosed herein in a prime-boost administration regimen is not critical to the successful practice hereof. Any vehicle capable of delivering the antigen (or effectuating expression of the antigen) to sufficient levels such that a cellular and/or humoral-mediated response is elicited should be sufficient to prime or boost the presently disclosed administration. Suitable viral vehicles include but are not limited to distinct serotypes of adenovirus, including but not limited to adenovirus serotypes 6, 24, 34 and 35 (see, e.g., PCT/US02/32512, published Apr. 17, 2003 (Ad6); PCT/US2003/026145, published Mar. 4, 2004 (Ad24, Ad34); PCT/NL00/00325, published Nov. 23, 2000 (Ad35)). Alternatively, the adenoviral administration can be followed or preceded by a viral vehicle of diverse origin. Examples of different viral vehicles include but are not limited to adeno-associated virus (“AAV”; see, e.g., Samulski et al., 1987 J. Virol. 61:3096-3101; Samulsid et al., 1989 J. Virol. 63:3822-3828); retrovirus (see, e.g., Miller, 1990 Human Gene Ther. 1:5-14; Ausubel et al., Current Protocols in Molecular Biology); pox virus (including but not limited to replication-impaired NYVAC, ALVAC, TROVAC and MVA vectors, see, e.g., Panicali & Paoletti, 1982 Proc. Natl. Acad. Sci. USA 79:4927-31; Nakano et al. 1982 Proc. Natl. Acad. Sci. USA 79: 1593-1596; Piccini et al., In Methods in Enzymology 153:545-63 (Wu & Grossman, eds., Academic Press, San Diego); Sutter et al., 1994 Vaccine 12:1032-40; Wyatt et al., 1996 Vaccine 15:1451-8; and U.S. Pat. Nos. 4,603,112; 4,769,330; 4,722,848; 4,603,112; 5,110,587; 5,174,993; and 5,185,146); and alpha virus (see, e.g., WO 92/10578; WO 94/21792; WO 95/07994; and U.S. Pat. Nos. 5,091,309 and 5,217,879). Prime-boost protocols exploiting adenoviral and pox viral vectors for delivery of HIV antigens are discussed in International Application No. PCT/US03/07511, published Sep. 18, 2003. An alternative to the above immunization schemes would be to employ polynucleotide administrations (including but not limited to “naked DNA” or facilitated polynucleotide delivery) in conjunction with an adenoviral prime and/or boost; see, e.g., Wolff et al., 1990 Science 247:1465, and the following patent publications: U.S. Pat. Nos. 5,580,859; 5,589,466; 5,739,118; 5,736,524; 5,679,647; WO 90/11092 and WO 98/04720. Another alternative would be to employ purified/recombinant protein administration in a prime-boost scheme along with adenovirus.
Potential hosts/vaccinees/individuals that can be administered the recombinant adenoviral vectors of the present invention include but are not limited to primates and especially humans and non-human primates, and include any non-human mammal of commercial or domestic veterinary importance.
Compositions of adenoviral vectors whether of single or multiple serotype, including but not limited to vaccine compositions, administered in accordance with the methods and compositions of the present invention may be administered alone or in combination with other viral- or non-viral-based DNA/protein vaccines. They also may be administered as part of a broader treatment regimen. The present invention, thus, encompasses those situations where the disclosed adenoviral cocktails are administered in conjunction with other therapies; including but not limited to other antimicrobial (e.g., antiviral, antibacterial) agent treatment therapies. A specific antimicrobial agent(s) selected is not critical to successful practice of the methods disclosed herein. The antimicrobial agent can, for example, be based on/derived from an antibody, a polynucleotide, a polypeptide, a peptide, or a small molecule. Any antimicrobial agent that effectively reduces microbial replication/spread/load within an individual is sufficient for the uses described herein.
Antiviral agents antagonize the functioning/life cycle of a virus, and target a protein/function essential to the proper life cycle of the virus; an effect that can be readily determined by an in vivo or in vitro assay. Some representative antiviral agents which target specific viral proteins are protease inhibitors, reverse transcriptase inhibitors (including nucleoside analogs; non-nucleoside reverse transcriptase inhibitors; and nucleotide analogs), and integrase inhibitors. Protease inhibitors include, for example, indinavir/CRIXIVAN®; ritonavir/NORVIR®; saquinavir/FORTOVASE®; nelfmavir/VIRACEPT®; amprenavir/AGENERASE®; lopinavir and ritonavir/KALETRA®. Reverse transcriptase inhibitors include, for example, (1) nucleoside analogs, e.g., zidovudine/RETROVIR® (AZT); didanosine/VIDEX® (ddI); zalcitabine/HIVID® (ddC); stavudine/ZERIT® (d4T); lamivudine/EPIVIR® (3TC); abacavir/ZIAGEN® (ABC); (2) non-nucleoside reverse transcriptase inhibitors, e.g., nevirapine/VIRAMUNE® (NVP); delavirdine/RESCRIPTOR® (DLV); efavirenz/SUSTIVA® (EFV); and (3) nucleotide analogs, e.g., tenofovir DF/VIREAD® (TDF). Integrase inhibitors include, for example, the molecules disclosed in U.S. Application Publication No. US2003/0055071, published Mar. 20, 2003; and International Application WO 03/035077. The antiviral agents, as indicated, can target as well a function of the virus/viral proteins, such as, for instance the interaction of regulatory proteins tat or rev with the trans-activation response region (“TAR”) or the rev-responsive element (“RRE”), respectively. An antiviral agent is, preferably, selected from the class of compounds consisting of: a protease inhibitor, an inhibitor of reverse transcriptase, and an integrase inhibitor. Preferably, the antiviral agent administered to an individual is some combination of effective antiviral therapeutics such as that present in highly active anti-retroviral therapy (“HAART”), a term generally used in the art to refer to a cocktail of inhibitors of viral protease and reverse transcriptase.
One of skill in the art can appreciate that the present invention can be employed in conjunction with any pharmaceutical composition useful for the treatment of microbial infections. Antimicrobial agents are typically administered in their conventional dosage ranges and regimens as reported in the art, including the dosages described in the Physicians' Desk Reference, 54th edition, Medical Economics Company, 2000.
Compositions comprising the recombinant viral vectors may contain physiologically acceptable components, such as buffer, normal saline or phosphate buffered saline, sucrose, other salts and polysorbate. In specific embodiments the viral particles are formulated in A195 formulation buffer. In certain embodiments, the formulation has: 2.5-10 mM TRIS buffer, preferably about 5 mM TRIS buffer; 25-100 mM NaCl, preferably about 75 mM NaCl; 2.5-10% sucrose, preferably about 5% sucrose; 0.01-2 mM MgCl2; and 0.001%-0.01% polysorbate 80 (plant derived). The pH should range from about 7.0-9.0, preferably about 8.0. One skilled in the art will appreciate that other conventional vaccine excipients may also be used in the formulation. In specific embodiments, the formulation contains 5 mM TRIS, 75 mM NaCl, 5% sucrose, 1 mM MgCl2, 0.005% polysorbate 80 at pH 8.0. This has a pH and divalent cation composition which is near the optimum for virus stability and minimizes the potential for adsorption of virus to glass surface. It does not cause tissue irritation upon intramuscular injection. It is preferably frozen until use.
The amount of viral particles in the vaccine composition(s) to be introduced into a vaccine recipient will depend on the strength of the transcriptional and translational promoters used and on the immunogenicity of the expressed gene product(s). In general, an immunologically or prophylactically effective dose of 1×107 to 1×1012 particles and preferably about 1×1010 to 1×1011 particles per adenoviral vector is administered directly into muscle tissue. Subcutaneous injection, intradermal introduction, impression through the skin, and other modes of administration such as intraperitoneal, intravenous, or inhalation delivery are also contemplated. One of ordinary skill in the art can also appreciate that different modes of administration can be employed to administer the different viruses of the methods and compositions taught herein. For instance, one of ordinary skill in the art can appreciate that one serotype can feasibly be administered via one injection route and another serotype via another route and still maintain contemporaneous delivery. Preferably, the total dose of adenoviral particles administered (different serotypes combined) does not exceed 1×1012.
Administration of additional agents able to potentiate or broaden the immune response (e.g., the various cytokines, interleukins), concurrently with or subsequent to parenteral introduction of the viral vectors of this invention is appreciated herein as well and can be advantageous.
The benefits of administration as described herein should be (1) a comparable or broader population of individuals successfully immunized/treated with recombinant adenoviral vectors, and (2) in situations of immunization, a lower transmission rate to (or occurrence rate in) previously uninfected individuals (i.e., prophylactic applications) and/or a reduction in/control of the levels of virus/bacteria/foreign agent within an infected individual (i.e., therapeutic applications).
The following non-limiting examples are presented to better illustrate the workings of the invention.
A. Human Samples
Serum samples were collected from HIV-infected patients from six countries—North America, Brazil, Thailand, Malawi, South Africa, and Cameroon. The samples were complement-inactivated at 56° C. for 90 mins before use.
B. Neutralization Assay
In vitro measurements of adenovirus neutralization titers were conducted following procedures previously reported; see, e.g., Aste-Amézaga, 2004 Hum. Gene Ther. 15:293-304. Neutralization titers against human adenovirus serotypes 5 and 6 (Ad5 and Ad6, respectively) were determined using vectors expressing secreted alkaline phosphatase.
C. Results
The titers were distributed among four ranges: (a) <18 or undetectable, (b) 18-200, (c) 201-1000, and (d) >1000. The results are shown in
It was observed that when an individual has a high Ad5 titer, the Ad6 were much lower and vice versa. Applicants decided to test the ability of a cocktail of Ad5- and Ad6-based vaccine vectors in the circumvention of any limitation due to high neutralizing activity to either one. The “effective titer” against such a cocktail of viruses was determined to be the lower of the adenovirus titers (in this case, Ad5 or Ad6 titers) since the vaccine component corresponding to that vector would be more potent.
A. HIV-1 gag Gene
A synthetic gene for HIV Gag from HIV-1 strain CAM-1 was constructed using codons frequently used in humans; see Korber et al., 1998 Human Retroviruses and AIDS, Los Alamos Nat'l Lab., Los Alamos, N.M.; and Lathe, R., 1985 J. Mol. Biol. 183:1-12.
A KOZAK sequence (GCCACC) was introduced proceeding the initiating ATG of the gag gene for optimal expression. The HIV gag fragment with KOZAK sequence was amplified through PCR from a V1Jns-HIV gag vector. PV1JnsFHVgag is a plasmid comprising the CMV immediate-early (IE) promoter and intron A, a full-length codon-optimized HIV gag gene, a bovine growth hormone-derived polyadenylation and transcriptional termination sequence, and a minimal pUC backbone; see Montgomery et al., 1993 DNA Cell Biol. 12:777-783, for a description of the plasmid backbone.
B. MRKAd5gag Construction and Virus Rescue
1. Removal of the Intron A Portion of the hCMV Promoter
GMP grade pV1JnsHIVgag was used as the starting material to amplify the hCMV promoter. The amplification was performed with primers suitably positioned to flank the hCMV promoter. A 5′ primer was placed upstream of the Msc1 site of the hCMV promoter and a 3′ primer (designed to contain the BglII recognition sequence) was placed 3′ of the hCMV promoter. The resulting PCR product (using high fidelity Taq polymerase) which encompassed the entire hCMV promoter (minus intron A) was cloned into TOPO PCR blunt vector and then removed by double digestion with Msc1 and BglII. This fragment was then cloned back into the original GMP grade pV1JnsHIVgag plasmid from which the original promoter, intron A, and the gag gene were removed following Msc1 and BglII digestion. This ligation reaction resulted in the construction of a hCMV promoter (minus intron A)+bGHpA expression cassette within the original pV1JnsHIVgag vector backbone. This vector is designated pV1JnsCMV (no intron).
The FLgag gene was excised from pV1JnsHIVgag using BglII digestion and the 1,526 bp gene was gel purified and cloned into pV1JnsCMV (no intron) at the BglII site. Colonies were screened using Sma1 restriction enzymes to identify clones that carried the FLgag gene in the correct orientation. This plasmid, designated pV1JnsCMV(no intron)-FLgag-bGHpA, was fully sequenced to confirm sequence integrity.
2. Construction of the Modified Shuttle Vector—“MRKpdelE1 Shuttle”
The modifications to the original Ad5 shuttle vector (pdelE1sp1A; a vector comprising Ad5 sequences from base pairs 1-341 and 3524-5798, with a multiple cloning region between nucleotides 341 and 3524 of Ad5, included the following three manipulations carried out in sequential cloning steps as follows:
(1) The left ITR region was extended to include the Pac1 site at the junction between the vector backbone and the adenovirus left ITR sequences. This allowed for easier manipulations using the bacterial homologous recombination system.
(2) The packaging region was extended to include sequences of the wild-type (WT) adenovirus from 342 bp to 450 bp inclusive.
(3) The area downstream of pIX was extended 13 nucleotides (i.e., nucleotides 3511-3523 inclusive).
These modifications effectively reduced the size of the E1 deletion without overlapping with any part of the E1A/E1B gene present in the transformed PER.C6® cell line. All manipulations were performed by modifying the Ad shuttle vector pdelE1sp1A.
Once the modifications were made to the shuttle vector, the changes were incorporated into the original Ad5 adenovector backbone pAdHVE3 by bacterial homologous recombination using E. coli BJ5183 chemically competent cells.
3. Construction of Modified Adenovector Backbone
An original adenovector pADHVE3 (comprising all Ad5 sequences except those nucleotides encompassing the E1 region) was reconstructed so that it would contain the modifications to the E1 region. This was accomplished by digesting the newly modified shuttle vector (MRKpdelE1 shuttle) with Pac1 and BstZ1101 and isolating the 2,734 bp fragment which corresponds to the adenovirus sequence. This fragment was co-transformed with DNA from Cla1 linearized pAdHVE3 (E3+adenovector) into E. coli BJ5183 competent cells. At least two colonies from the transformation were selected and grown in Terrific™ broth for 6-8 hours until turbidity was reached. DNA was extracted from each cell pellet and then transformed into E. coli XL1 competent cells. One colony from the transformation was selected and grown for plasmid DNA purification. The plasmid was analyzed by restriction digestions to identify correct clones. The modified adenovector was designated MRKpAdHVE3 (E3+plasmid). Virus from the new adenovector (MRKHVE3) as well as the old version were generated in the PER.C6® cell lines. In addition, the multiple cloning site of the original shuttle vector contained ClaI, BamHI, Xho I, EcoRV, HindIII, Sal I, and Bgl II sites. This MCS was replaced with a new MCS containing Not I, Cla I, EcoRV and Asc I sites. This new MCS has been transferred to the MRKpAdHVE3 pre-plasmid along with the modification made to the packaging region and pIX gene.
4. Construction of the New Shuttle Vector Containing Modified Gag Transgene—“MRKpdelE1-CMV (No Intron)-FLgag-bGHpA”
The modified plasmid pV1JnsCMV(no intron)-FLgag-bGHpA was digested with Msc1 overnight and then digested with Sfi1 for 2 hours at 50° C. The DNA was then treated with Mungbean nuclease for 30 minutes at 30° C. The DNA mixture was desalted using the Qiaex II kit and then Klenow treated for 30 minutes at 37° C. to fully blunt the ends of the transgene fragment. The 2,559 bp transgene fragment was then gel purified. The modified shuttle vector (MRKpdelE1 shuttle) was linearized by digestion with EcoRV, treated with calf intestinal phosphatase and the resulting 6,479 bp fragment was then gel purified. The two purified fragments were then ligated together and several dozen clones were screened to check for insertion of the transgene within the shuttle vector. Diagnostic restriction digestion was performed to identify those clones carrying the transgene in the E1 parallel orientation.
5. Construction of the MRK FG Adenovector
The shuttle vector containing the HIV-1 gag transgene in the E1 parallel orientation, MRKpdelE1-CMV(no intron)-FLgag-bGHpA, was digested with Pac1. The reaction mixture was digested with BsfZ171. The 5,291 bp fragment was purified by gel extraction. The MRKpAdHVE3 plasmid was digested with Cla1 overnight at 37° C. and gel purified. About 100 ng of the 5,290 bp shuttle+transgene fragment and ˜100 ng of linearized MRKpAdHVE3 DNA were co-transformed into E. coli BJ5183 chemically competent cells. Several clones were selected and grown in 2 ml Terrific™ broth for 6-8 hours, until turbidity was reached. The total DNA from the cell pellet was purified using Qiagen alkaline lysis and phenol chloroform method. The DNA was precipitated with isopropanol and resuspended in 20 μl dH20. A 2 μl aliquot of this DNA was transformed into E. coli XL-1 competent cells. A single colony from the transformation was selected and grown overnight in 3 ml LB+100 μg/ml ampicillin. The DNA was isolated using Qiagen columns. A positive clone was identified by digestion with the restriction enzyme BstEII which cleaves within the gag gene as well as the plasmid backbone. The pre-plasmid clone is designated MRKpAdHVE3+CMV(no intron)-FLgag-bGHpA and is 37,498 bp in size. A nucleotide sequence for pMRKAd5HIV-1gag adenoviral vector and details of its construction are disclosed in PCT/US01/28861, published Mar. 21, 2002.
6. Virus Generation of an Enhanced Adenoviral Construct—“MRK Ad5 HIV-1gag”
MRK Ad5 HIV-1 gag contains the hCMV (no intron)-FLgag-bGHpA transgene inserted into the new E3+ adenovector backbone, MRKpAdHVE3, in the E1 parallel orientation. We have designated this adenovector MRK Ad5 HIV-1 gag. This construct was prepared as outlined below:
The pre-plasmid MRKpAdHVE3+CMV (no intron)-FLgag-bGHpA was digested with Pac1 to release the vector backbone and 3.3 μg was transfected by the calcium phosphate method (Amersham Pharmacia Biotech.) in a 6 cm dish containing PER.C6® cells at ˜60% confluence. Once CPE was reached (7-10 days), the culture was freeze/thawed three times and the cell debris pelleted. 1 ml of this cell lysate was used to infect into a 6 cm dish containing PER.C6® cells at 80-90% confluence. Once CPE was reached, the culture was freeze/thawed three times and the cell debris pelleted. The cell lysate was then used to infect a 15 cm dish containing PER.C6® cells at 80-90% confluence. This infection procedure was continued and expanded at passage 6. The virus was then extracted from the cell pellet by CsCl method. Two bandings were performed (3-gradient CsCl followed by a continuous CsCl gradient). Following the second banding, the virus was dialyzed in A105 buffer. Viral DNA was extracted using pronase treatment followed by phenol chloroform. The viral DNA was then digested with HindIII and radioactively labeled with [33P]dATP. Following gel electrophoresis to separate the digestion products the gel was dried down on Whatman paper and then subjected to autoradiography. The digestion products were compared with the digestion products from the pre-plasmid (that had been digested with Pac1/HindIII prior to labeling). The expected sizes were observed, indicating that the virus had been successfully rescued.
C. HIV-1 pol Gene
A synthetic gene for HIV Pol from HIV-1 was constructed using codons frequently used in humans; see Korber et al., 1998 Human Retroviruses and AIDS, Los Alamos Nat'l Lab., Los Alamos, N.M.; and Lathe, R., 1985 J. Mol. Biol. 183:1-12. The protein sequence is based on that of Hxb2r, a clonal isolate of IIIB; this sequence has been shown to be closest to the consensus clade B sequence with only 16 nonidentical residues out of 848 (Korber et al., 1998 Human Retroviruses and AIDS, Los Alamos National Laboratory, Los Alamos, N.M.). The protease gene is excluded from the DNA vaccine constructs herein to insure safety from any residual protease activity in spite of mutational inactivation.
D. MRKAd5Pol Construction and Virus Rescue
1. Construction of Vector: Shuttle Plasmid and Pre-adenovirus Plasmid
Key steps performed in the construction of the vectors, including the pre-adenovirus plasmid denoted MRKAd5pol, is depicted in
2. Generation of Research-grade Recombinant Adenovirus
The pre-adenovirus plasmid, pMRKAd5pol, was rescued as infectious virions in PER.C6® adherent monolayer cell culture. To rescue infectious virus, 12 μg of pMRKAd5pol was digested with restriction enzyme PacI (New England Biolabs) and 3.3 μg was transfected per 6 cm dish of PER.C6® cells using the calcium phosphate co-precipitation technique (Cell Phect Transfection Kit, Amersham Pharmacia Biotech Inc.). PacI digestion releases the viral genome from plasmid sequences allowing viral replication to occur after entry into PER.C6® cells. Infected cells and media were harvested 6-10 days post-transfection, after complete viral cytopathic effect (CPE) was observed. Infected cells and media were stored at ≦−60° C. This pol containing recombinant adenovirus is referred to herein as “MRKAd5pol”. This recombinant adenovirus expresses an inactivated HIV-1 Pol protein as shown in SEQ ID NO: 6.
E. HIV-1 nef Gene
A synthetic gene for HIV Nef from HIV-1 was constructed using codons frequently used in humans; see Korber et al., 1998 Human Retroviruses and AIDS, Los Alamos Nat'l Lab., Los Alamos, N.M.; and Lathe, R., 1985 J. Mol. Biol. 183:1-12.
F. MRKAd5Nef Construction and Virus Rescue
1. Construction of Vector: Shuttle Plasmid and Pre-adenovirus Plasmid
Key steps performed in the construction of the vectors, including the pre-adenovirus plasmid denoted MRKAd5nef, is depicted in
2. Generation of Research-grade Recombinant Adenovirus
The pre-adenovirus plasmid, pMRKAd5nef, was rescued as infectious virions in PER.C6® adherent monolayer cell culture. To rescue infectious virus, 12 μg of pMRKAdnef was digested with restriction enzyme Pac1 (New England Biolabs) and 3.3 μg was transfected per 6 cm dish of PER.C6® cells using the calcium phosphate co-precipitation technique (Cell Phect Transfection Kit, Amersham Pharmacia Biotech Inc.). Pac1 digestion releases the viral genome from plasmid sequences allowing viral replication to occur after entry into PER.C6® cells. Infected cells and media were harvested 6-10 days post-transfection, after complete viral cytopathic effect (CPE) was observed. Infected cells and media were stored at ≦−60° C. This nef containing recombinant adenovirus is now referred to as “MRKAd5nef”.
G. Generation of Adenoviral Serotype 6 Vector Constructs
1. Construction of Ad6 Pre-Adenovirus Plasmid
The general strategy used to recover a pMRKAd6E1-bacterial plasmid is illustrated in
pMRKAd6E1—can then be used to generate first generation Ad6 vectors containing transgenes in E1.
2. Construction of an Ad6 Pre-Adenovirus Plasmid Containing the HIV-1 Gag Gene
(A) Construction of Adenoviral Shuttle Vector
A synthetic full-length codon-optimized HIV-1 gag gene was inserted into a universal shuttle vector comprising adenovirus serotype 6 (“Ad6”) sequences from bp1 to bp450 and bp bp3508 to bp3807 (basepairs 451 to 3507 are deleted), a CMV promoter (minus Intron A) and bGHpA. Direction of transcription was E1 parallel. The synthetic full-length codon-optimized HIV-1 gag gene was obtained from plasmid pV1Jns-HIV-FLgag-opt by BglII digestion, gel purified and ligated into the BglII restriction endonuclease site in the shuttle vector. The genetic structure of the resultant shuttle vector comprising full length gag was verified by PCR, restriction enzyme and DNA sequence analyses.
(B) Construction of Pre-adenovirus Plasmid
The shuttle vector was digested with restriction enzymes Pac1 and Bst1 107I and then co-transformed into E. coli strain BJ5183 with linearized (ClaI-digested) adenoviral backbone plasmid, pAd6E1−E3+. The genetic structure of the resulting pMRKAd6gag was verified by restriction enzyme and DNA sequence analysis. The vectors were transformed into competent E. coli XL-1 Blue for large-scale production. The recovered plasmid was verified by restriction enzyme digestion and DNA sequence analysis, and by expression of the gag transgene in transient transfection cell culture.
pMRKAd6gag contains Ad6 bps 1 to 450 and bps 3508 to 35759 (bp numbers refer correspond to that of an Ad6 sequence; see, e.g., PCT/US02/32512, published Apr. 17, 2003). In the plasmid the viral ITRs are joined by plasmid sequences that contain the bacterial origin of replication and an ampicillin resistance gene.
(C) Generation of Research-grade Recombinant MRKAd6gag
To prepare virus for pre-clinical immunogenicity studies, the pre-adenovirus plasmid pMRKAd6gag was rescued as infectious virions in PER.C6® adherent monolayer cell culture. To rescue infectious virus, 10 μg of pMRKAd6gag was digested with restriction enzyme PacI (New England Biolabs) and transfected into a 6 cm dish of PER.C6® cells using the calcium phosphate co-precipitation technique (Cell Phect Transfection Kit, Amersham Pharmacia Biotech Inc.). PacI digestion releases the viral genome from plasmid sequences allowing viral replication to occur after entry into PER.C6® cells. Infected cells and media were harvested after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by multiple passages in PER.C6® cells. At the final passage virus was purified from the cell pellet by CsCl ultracentrifugation. The identity and purity of the purified virus was confirmed by restriction endonuclease analysis of purified viral DNA and by Gag ELISA of culture supernatants from virus infected mammalian cells grown in vitro. For restriction analysis, digested viral DNA was end-labeled with P33-dATP, size-fractionated by agarose gel electrophoresis, and visualized by autoradiography.
All viral constructs were confirmed for Gag expression by Western blot analysis.
3. Construction of an Ad6 Pre-Adenovirus Plasmid Containing the HIV-1 nef Gene
(A) Construction of Adenoviral Shuttle Vector
A synthetic full-length codon-optimized HIV-1 nef gene (opt nef G2A, LLAA) was inserted into a universal shuttle vector comprising adenovirus serotype 6 (“Ad6”) sequences from bp1 to bp450 and bp bp3508 to bp3807 (basepairs 451 to 3507 are deleted), a CMV promoter (minus Intron A) and bGHpA. Direction of transcription was E1 parallel. The synthetic full-length codon-optimized HIV-1 nef gene was obtained from plasmid pV1Jns-HIV-FLnef-opt by BglII digestion, gel purified and ligated into the BglII restriction endonuclease site in the shuttle vector. The genetic structure of the resultant shuttle vector comprising full length nef was verified by PCR, restriction enzyme and DNA sequence analyses.
(B) Construction of Pre-adenovirus Plasmid
The shuttle vector was digested with restriction enzymes Pac1 and Bst1 107I and then co-transformed into E. coli strain BJ5183 with linearized (ClaI-digested) adenoviral backbone plasmid, pAd6E1−E3+. The genetic structure of the resulting pMRKAd6nef was verified by restriction enzyme and DNA sequence analysis. The vectors were transformed into competent E. coli XL-1 Blue for large-scale production. The recovered plasmid was verified by restriction enzyme digestion and DNA sequence analysis, and by expression of the nef transgene in transient transfection cell culture.
pMRKAd6nef contains Ad6 bps 1 to 450 and bps 3508 to 35759 (bp numbers refer correspond to that of an Ad6 sequence; see, e.g., PCT/US02/32512, published Apr. 17, 2003). In the plasmid the viral ITRs are joined by plasmid sequences that contain the bacterial origin of replication and an ampicillin resistance gene.
(C) Generation of Research-grade Recombinant MRKAd6nef
To prepare virus for pre-clinical immunogenicity studies, the pre-adenovirus plasmid pMRKAd6nef was rescued as infectious virions in PER.C6® adherent monolayer cell culture. To rescue infectious virus, 10 μg of pMRKAd6nef was digested with restriction enzyme PacI (New England Biolabs) and transfected into a 6 cm dish of PER.C6® cells using the calcium phosphate co-precipitation technique (Cell Phect Transfection Kit, Amersham Pharmacia Biotech Inc.). PacI digestion releases the viral genome from plasmid sequences allowing viral replication to occur after entry into PER.C6® cells. Infected cells and media were harvested after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by multiple passages in PER.C6® cells. At the final passage virus was purified from the cell pellet by CsCl ultracentrifugation. The identity and purity of the purified virus was confirmed by restriction endonuclease analysis of purified viral DNA and by nef ELISA of culture supernatants from virus infected mammalian cells grown in vitro. For restriction analysis, digested viral DNA was end-labeled with P33-dATP, size-fractionated by agarose gel electrophoresis, and visualized by autoradiography.
All viral constructs were confirmed for nef expression by Western blot analysis.
H. Construction of an Ad5 Vector Containing HIV Gag and Nef Transgenes
MRKAd5gagnef is depicted in
Key steps involved in the construction of MRKAd5gagnef are depicted in
1. Construction of Adenoviral Shuttle Vector
The shuttle plasmid pMRKAd5-HCMV-nef-BGHpA-MCMV36gagSV40-S was constructed by inserting the gag expression cassette into the AscI site in pMRKAd5-hCMV-nef-BGHpA. The gag expression cassette was obtained by PCR using S-MRKAd5MCMV36gagSV40pA as template. The PCR primers were designed to introduce AscI sites at each end of the transgene. The AscI digested PCR fragment was ligated with pMRKAd5-hCMV-nef-BGHpA, also digested with AscI, generating pMRKAd5-hCMV-nef-BGHpA-mCMV36gagSV40-S. The genetic structure of pMRKAd5-hCMV-nef-BGHpA-mCMV36gagSV40-S was verified by restriction enzyme analyses and sequencing.
2. Construction of Pre-adenovirus Plasmid
To construct pre-adenovirus pMRKAd5gagnef, the transgene containing fragment was liberated from shuttle plasmid pMRKAd5-hCMV-nef-BGHpA-mCMV36gagSV40-S by digestion with restriction enzymes BstZ17I+SgrAI and gel purified. The purified transgene fragment was then co-transformed into E. coli strain BJ5183 with linearized (ClaI-digested) adenoviral backbone plasmid, pHVE3. Plasmid DNA isolated from BJ5183 transformants was then transformed into competent E. coli Sab12™ for screening by restriction analysis. The desired plasmid pMRKAd5gagnef (also referred to as pMRKAd5-hCMV-nef-BGH-mCMV36gagSV40-S) was verified by restriction enzyme digestion and DNA sequence analysis.
3. Generation of Recombinant MRKAd5gagnef
To prepare virus, the pre-adenovirus plasmid pMRKAd5gagnef was rescued as infectious virions in PER.C6™ adherent monolayer cell culture. To rescue infectious virus, 10 μg of pMRKAd5gagnef was digested with restriction enzyme PacI (New England Biolabs) and then transfected into one T25 flask of PER.C6™cells using the calcium phosphate co-precipitation technique. PacI digestion releases the viral genome from plasmid sequences, allowing viral replication to occur after entry into PER.C6™ cells. Infected cells and media were harvested 7 days post-transfection, after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by 2 passages in PER.C6™ cells. At passage 2, virus was purified on CsCl density gradients. To verify that the rescued virus had the correct genetic structure, viral DNA was isolated and analyzed by restriction enzyme (HindIII) analysis. The expression of Gag and Nef was also verified by ELISA and Western blot. The rescued virus was referred to as MRKAd5gagnef (also referred to as MRK-Ad5-hCMVnefbGH-MCMV36gagSV40-S).
I. Construction of an Ad6 Vector Containing HIV Gag and Nef Transgenes
MRKAd6gagnef is depicted in
Key steps involved in the construction of MRKAd6gagnef are depicted in
1. Construction of Adenoviral Shuttle Vector
The shuttle plasmid pMRKAd6-hCMV-nefG2A-BGHpA-mCMV36gagSV40-S was constructed by inserting the gag expression cassette into the AscI site in pMRKAd6-hCMV-nefG2A-BGHpA. The gag expression cassette was obtained by PCR using S-MRKAd5-mCMV36gagSV40 as template. The PCR primers were designed to introduce AscI sites at each end of the transgene. The AscI digested PCR fragment was ligated with pMRKAd6-hCMV-nefG2A-BGHpA, also digested with AscI, generating pMRKAd6-hCMV-nefG2A-BGHpA-mCMV36gagSV40-S. The genetic structure of pMRKAd6-hCMV-nefG2A-BGHpA-mCMV36gagSV40-S was verified by restriction enzyme analyses and sequencing.
2. Construction of Pre-adenovirus Plasmid
To construct pre-adenovirus pMRKAd6gagnef, the transgene containing fragment was liberated from shuttle plasmid pMRKAd6-hCMV-nefG2A-BGHpA-mCMV36gagSV40-S by digestion with restriction enzymes Pac1 and PmeI and gel purified. The purified transgene fragment was then co-transformed into E. coli strain BJ5183 with linearized (ClaI-digested) adenoviral backbone plasmid, pMRKAd6E1−. Plasmid DNA isolated from BJ5183 transformants was then transformed into competent E. coli XL-1 Blue for screening by restriction analysis. The desired plasmid pMRKAd6gagnef (also referred to as pMRKAd6-hCMV-nefG2A-BGH-mCMV36gagSV40-S) was verified by restriction enzyme digestion and DNA sequence analysis.
3. Generation of Recombinant MRKAd6gagnef
To prepare virus the pre-adenovirus plasmid pMRKAd6gagnef was rescued as infectious virions in PER.C6™ adherent monolayer cell culture. To rescue infectious virus, 10 μg of pMRKAd6gagnef was partially digested with restriction enzyme PacI (New England Biolabs) and then transfected into one T25 flask of PER.C6™ cells using the calcium phosphate co-precipitation technique. pMRKAd6gagnef contains three PacI restriction sites. One at each ITR and one located in early region 3. Digestion conditions were used which favored the linearization of pMRKAd6gagnef (digestion at only one of the three PacI sites) since the release of only one ITR is required to allow the initiation of viral DNA replication after entry into PER.C6® cells. Infected cells and media were harvested 7 days post-transfection, after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by 2 passages in PER.C6™ cells. At passage 2 virus was purified on CsCl density gradients. To verify that the rescued virus had the correct genetic structure, viral DNA was isolated and analyzed by restriction enzyme (HindIII) analysis. The expression of Gag and Nef was also verified by ELISA. The rescued virus was referred to as MRKAd6gagnef (also referred to as Ad6-hCMVnefG2AbGH-MCMV36gagSV40-S).
J. Construction of an Ad5 Vector Containing an HIV-1 Gagpol Fusion Transgene
MRKAd5gagpol is depicted in
Key steps involved in the construction of MRKAd5gagpol are depicted in
1. Construction of Adenoviral Shuttle Vector
The shuttle plasmid pMRKAd5gagpol was constructed by inserting a synthetic full-length codon-optimized HIV-1 gagpol fusion gene into MRKpdelE1(Pac/pIX/pack450)+CMVmin+BGHpA(str.). The synthetic full-length codon-optimized HIV-1 gagpol gene was obtained by overlap PCR as depicted in
2. Construction of Pre-adenovirus Plasmid
To construct pre-adenovirus pMRKAd5DE1HCMVgagpolBGHpADE3, the transgene containing fragment was liberated from shuttle plasmid pMRKAd5gagpol by digestion with restriction enzymes Pac1 and BstZ17I and gel purified. The purified transgene fragment was then co-transformed into E. coli strain BJ5183 with linearized (ClaI-digested) adenoviral backbone plasmid, pAd5HVO (also referred to as pAd5 E1−E3−). Plasmid DNA isolated from BJ5183 transformants was then transformed into competent E. coli XL-1 Blue for screening by restriction analysis. The desired plasmid pMRKAd5DE1HCMVgagpolBGHpADE3 (also referred to as pAd5HVOMRKgagpol) was verified by restriction enzyme digestion and DNA sequence analysis.
3. Generation of Recombinant MRKAd5gagpol
To prepare virus the pre-adenovirus plasmid pMRKAd5DE1HCMVgagpolBGHpADE3 was rescued as infectious virions in PER.C6™ adherent monolayer cell culture. To rescue infectious virus, 10 μg of pMRKAd5DE1HCMVgagpolBGHpADE3 was digested with restriction enzyme PacI (New England Biolabs) and then transfected into one T25 flask of PER.C6® cells using the calcium phosphate co-precipitation technique. PacI digestion releases the viral genome from plasmid sequences, allowing viral replication to occur after entry into PER.C6™ cells. Infected cells and media were harvested 10 days post-transfection, after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by 2 passages in PER.C6™ cells. At passage 2, virus was purified on CsCl density gradients. To verify that the rescued virus had the correct genetic structure, viral DNA was isolated and analyzed by restriction enzyme (HindIII) analysis. The expression of the GagPol fusion was also verified by Western blot. The rescued virus was referred to as MRKAd5gagpol.
The strategy followed to fuse the gag and pol open reading frames is outlined in
K. Construction of an Ad5 Vector Containing HIV Gagpol and Nef Transgenes
MRKAd5nef-gagpol is depicted in
Key steps involved in the construction of MRKAd5nef-gagpol are depicted in
1. Construction of Ad Shuttle Vector
Shuttle plasmid pMRKAd5HCMVnefMCMVgagpol was constructed in two steps. First the gagpol fusion open reading frame was obtained from pMRKAd5gagpol (described in Example 2J) by BglII digestion and inserted into the BglII site in S-MRKAd5-mCMV36-SV40, generating MRKAd5MCMVgagpolSV40. MRKAd5MCMVgagpolSV40 was then digested with MfeI and XhoI to generate a gagpol transgene containing fragment that was cloned into the MfeI and XhoI sites in MRKAd5-hCMVnefG2ABGH-mCMV36gagSv40-S, generating pMRKAd5HCMVnefMCMVgagpol. The genetic structure of pMRKAd5HCMVnefMCMVgagpol was verified by restriction enzyme analysis and sequencing.
2. Construction of Pre-adenovirus Plasmid
To construct pre-adenovirus pAd5MRKDE1HCMVnefG2ABGHMCMV36gagpolSV40DE3, the transgene containing fragment was liberated from shuttle plasmid pMRKAd5HCMVnefMCMVgagpol by digestion with restriction enzymes Pac1 and BstZ17I and gel purified. The purified transgene fragment was then co-transformed into E. coli strain BJ5183 with linearized (ClaI-digested) adenoviral backbone plasmid pAd5HVO, (also referred to as pAd5E1−E3−). Plasmid DNA isolated from BJ5183 transformants was then transformed into competent E. coli XL-1 Blue for screening by restriction analysis. The desired plasmid pAd5MRKDE1HCMVnefG2ABGHMCMV36gagpolSV40DE3 was verified by restriction enzyme digestion and DNA sequence analysis.
3. Generation of Recombinant MRKAd5nef-gagpol
To prepare virus the pre-adenovirus plasmid pAd5MRKDE1HCMVnefG2ABGHMCMV36gagpolSV40DE3 was rescued as infectious virions in PER.C6™ adherent monolayer cell culture. To rescue infectious virus, 10 μg of pAd5MRKDE1HCMVnefG2ABGHMCMV36gagpolSV40DE3 was digested with restriction enzyme PacI (New England Biolabs) and then transfected into one T25 flask of PER.C6™ cells using the calcium phosphate co-precipitation technique. PacI digestion releases the viral genome from plasmid sequences, allowing viral replication to occur after entry into PER.C6™ cells. Infected cells and media were harvested 10 days post-transfection, after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by 2 passages in PER.C6™ cells. At passage 2, virus was purified on CsCl density gradients. To verify that the rescued virus had the correct genetic structure, viral DNA was isolated and analyzed by restriction enzyme (HindIII) analysis. The expression of Nef and the GagPol fusion proteins were also verified by Western blot. The rescued virus was referred to as MRKAd5nef-gagpol.
L. Construction of an Ad5 Vector Containing an HIV Gagpolnef Fusion Transgene
MRKAd5gagpolnef is depicted in
Key steps involved in the construction of MRKAd5gagpolnef are depicted in FIGS. 32 to 34 and described in the text that follows.
1. Construction of Adenoviral Shuttle Vector
The shuttle plasmid pMRKAd5gagpolnef was constructed in three steps (
2. Construction of Pre-adenovirus Plasmid
To construct pre-adenovirus pMRKAd5DE1HCMVgagpolnefBGHpADE3 (
3. Generation of Recombinant MRKAd5gagpol
To prepare virus the pre-adenovirus plasmid pMRKAd5DE1HCMVgagpolnefBGHpADE3 was rescued as infectious virions in PER.C6™ adherent monolayer cell culture. To rescue infectious virus, 10 μg of pMRKAd5DE1HCMVgagpolnefBGHpADE3 was digested with restriction enzyme PacI (New England Biolabs) and then transfected into one T25 flask of PER.C6™ cells using the calcium phosphate co-precipitation technique. PacI digestion releases the viral genome from plasmid sequences, allowing viral replication to occur after entry into PER.C6™ cells. Infected cells and media were harvested 10 days post-transfection, after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by 2 passages in PER.C6™ cells. At passage 2, virus was purified on CsCl density gradients. To verify that the rescued virus had the correct genetic structure, viral DNA was isolated and analyzed by restriction enzyme (HindIII) analysis. The expression of the GagPolNef fusion was also verified by Western blot. The rescued virus was referred to as MRKAd5gagpolnef.
The strategy followed to fuse the pol and nef open reading frames is outlined in
M. Construction of an Ad6 Vector Containing HIV Gagpol and Nef Transgenes
MRKAd6nef-gagpol is depicted in
Key steps involved in the construction of MRKAd6nef-gagpol are depicted in
1. Construction of Ad Shuttle Vector
Shuttle plasmid pNEBAd6-2HCMVnefMCMVgagpol was constructed by inserting the nef-gagpol transgene from pMRKHCMVnefMCMVgagpol (described in Example 2K) into the AscI and NotI sites in pNEBAd6-2. To obtain the nef-gagpol transgene fragment, pMRKHCMVnefMCMVgagpol was digested to completion with NotI and PvuI and then partially digested with AscI. PvuI was used to digest and thus reduce in size the unwanted plasmid fragment so that the desired NotI/AscI transgene fragment could be more easily gel purified. Once purified the NotI/AscI transgene fragment was ligated with pNEBAd6-2 also digested with Not I and AscI, generating pNEBAd6-2HCMVnefMCMVgagpol. The genetic structure of pNEBAd6-2HCMVnefMCMVgagpol was verified by restriction enzyme analysis and sequencing.
2. Construction of Pre-adenovirus Plasmid
To construct pre-adenovirus pAd6MRKDE1HCMVnefBGHMCMVgagpolSV40DE3, the transgene containing fragment was liberated from shuttle plasmid pNEBAd6-2HCMVnefMCMVgagpol by digestion with restriction enzymes Pac1 and PmeI and gel purified. The purified transgene fragment was then co-transformed into E. coli strain BJ5183 with linearized (ClaI-digested) adenoviral backbone plasmid, pAd6MRKDE1DE3. Plasmid DNA isolated from BJ5183 transformants was then transformed into competent E. coli XL-1 Blue for screening by restriction analysis. The desired plasmid pAd6MRKDE1HCMVnefBGHMCMVgagpolSV40DE3 was verified by restriction enzyme digestion and DNA sequence analysis.
3. Generation of Recombinant MRKAd6nef-gagpol
To prepare virus the pre-adenovirus plasmid pAd6MRKDE1HCMVnefBGHMCMVgagpolSV40DE3 was rescued as infectious virions in PER.C6™ adherent monolayer cell culture. To rescue infectious virus, 10 μg of pAd6MRKDE1HCMVnefBGHMCMVgagpolSV40DE3 was digested with restriction enzyme PacI (New England Biolabs) and then transfected into one T25 flask of PER.C6™ cells using the calcium phosphate co-precipitation technique. PacI digestion releases the viral genome from plasmid sequences, allowing viral replication to occur after entry into PER.C6™ cells. Infected cells and media were harvested 10 days post-transfection, after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by 2 passages in PER.C6™ cells. At passage 2, virus was purified on CsCl density gradients. To verify that the rescued virus had the correct genetic structure, viral DNA was isolated and analyzed by restriction enzyme (HindIII) analysis. The expression of Nef and the GagPol fusion proteins were also verified by Western blot. The rescued virus was referred to as MRKAd6nef-gagpol.
N. Construction of an Ad6 Vector Containing an HIV Gagpolnef Fusion Transgene
MRKAd6gagpolnef is depicted in
Key steps involved in the construction of MRKAd6gagpolnef are depicted in
1. Construction of Ad Shuttle Vector
Shuttle plasmid pNEB Ad6-2gagpolnef was constructed by inserting the gagpolnef transgene from pMRKAd5gagpolnef (described in Example 2K) into the AscI and NotI sites in pNEBAd6-2. To obtain the gagpolnef transgene fragment, pMRKAd5gagpolnef was digested with NotI and AscI and transgene fragment gel purified. The NotI/AscI transgene fragment was then ligated with pNEBAd6-2 also digested with Not I and AscI, generating pNEBAd6-2HCMVgagpolnef. The genetic structure of pNEBAd6-2gagpolnef was verified by restriction enzyme analysis and sequencing.
2. Construction of Pre-adenovirus Plasmid
To construct pre-adenovirus pAd6MRKDE1HCMVgagpolnefBGHpADE3, the transgene containing fragment was liberated from shuttle plasmid pNEBAd6-2gagpolnef by digestion with restriction enzymes Pac1 and PmeI and gel purified. The purified transgene fragment was then co-transformed into E. coli strain BJ5183 with linearized (ClaI-digested) adenoviral backbone plasmid, pAd6MRKDE1DE3. Plasmid DNA isolated from BJ5183 transformants was then transformed into competent E. coli XL-1 Blue for screening by restriction analysis. The desired plasmid pAd6MRKDE1HCMVgagpolnefBGHpADE3 was verified by restriction enzyme digestion.
3. Generation of Recombinant MRKAd6gagpolnef
To prepare virus the pre-adenovirus plasmid pAd6MRKDE1HCMVgagpolnefBGHpADE3 was rescued as infectious virions in PER.C6™ adherent monolayer cell culture. To rescue infectious virus, 10 μg of pAd6MRKDE1HCMVgagpolnefBGHpADE3 was digested with restriction enzyme PacI (New England Biolabs) and then transfected into one T25 flask of PER.C6™ cells using the calcium phosphate co-precipitation technique. PacI digestion releases the viral genome from plasmid sequences, allowing viral replication to occur after entry into PER.C6™ cells. Infected cells and media were harvested 10 days post-transfection, after complete viral cytopathic effect (CPE) was observed. The virus stock was amplified by 2 passages in PER.C6™ cells. At passage 2, virus was purified on CsCl density gradients. To verify that the rescued virus had the correct genetic structure, viral DNA was isolated and analyzed by restriction enzyme (HindIII) analysis. The expression of the GagPolNef fusion protein was also verified by Western blot. The rescued virus was referred to as MRKAd6gagpolnef.
A. Immunization
Rhesus macaques were between 3-10 kg in weight. In all cases, the total dose of each vaccine was suspended in 1 ml of buffered solution. The macaques were anesthetized (ketamine-xylazine), and the vaccines were delivered intramuscularly (“i.m.”) in 0.5-mL aliquots into both deltoid muscles using tuberculin syringes (Becton-Dickinson, Franklin Lakes, N.J.). Plasma and peripheral blood mononuclear cells (PBMC) sampled were following standard protocols.
B. ELISPOT and ICS Assays
Ninety-six-well flat-bottomed plates (Millipore, Immobilon-P membrane) were coated with 1 μg/well of anti-gamma interferon (IFN-γ) mAb MD-1 (U-Cytech-BV) overnight at 4° C. The plates were then washed three times with PBS and blocked with R10 medium (RPMI, 0.05 mM 2-mercaptoethanol, 1 mM sodium pyruvate, 2 mM L-glutamate, 10 mM HEPES, 10% fetal bovine serum) for 2 h at 37° C. The medium was discarded from the plates, and freshly isolated peripheral blood mononuclear cells (PBMC) were added at 1-4×105 cells/well. The cells were stimulated in the absence (mock) or presence of a nef peptide pool (4 μg/mL per peptide). The pool, consisting of 15 amino acid (“aa”) (15-aa) peptides shifting by 4 aa (Synpep, CA), was constructed from the HIV-1 JRFL nef sequence. Cells were then incubated for 20-24 h at 37° C. in 5% CO2. Plates were washed six times with PBST (PBS, 0.05% Tween 20) and 100 μL/well of 1:400 dilution of anti-IFN-γ polyclonal biotinylated detector antibody solution (U-Cytech-BV) was added. The plates were incubated overnight at 37° C. The plates were washed six times with PBST. Color was developed by incubating in NBT/BCP (Pierce) for 10 mins. Spots, which represent IFN-γ secreting cells, were counted under a dissecting microscope and normalized to 1×106 PBMC.
C. Results
Nine macaques, prior to this protocol, had received multiple doses of a non-Nef-encoding Ad5 vector. The Ad5-specific neutralizing titers in these animals ranged from 2800 to >4600. The animals were distributed equally to three cohorts of three macaques. One cohort received 10ˆ10 vp MRKAd6 HIV nef at weeks 0, 4, and 30; the second cohort received 10ˆ10 vp MRKAd5 HIV nef at weeks 0, 4, and 30; and the third cohort received a mixture of 5×10ˆ9 vp MRKAd5 HIV nef and 5×10ˆ9 vp MRKAd6 HIV nef at weeks 0, 4 and 30. As controls, three cohorts of three naïve macaques received each of the three vaccines listed above.
When comparing the immune responses in animals that received the MRKAd5 HIV nef vector in the presence or absence of pre-existing Ad5 immunity, it is apparent that the responses were attenuated in the pre-exposed animals after the first Ad5 immunization. Pre-existing Ad5 immunity did not have any apparent detrimental effect on the induced Nef-specific immunity if either MRKAd6 HIV nef or the Ad5/Ad6 cocktail is used. This suggests that a vector-specific immunity to one Ad serotype can be circumvented by using another serotype. This study, therefore, supports the utility of cocktails of different Ad serotype vectors to improve the breadth of patient coverage and/or the magnitude of the induced immunity.
A. Immunization
Rhesus macaques were between 3-10 kg in weight. In all cases, the total dose of each vaccine was suspended in 1 mL of buffer. The macaques were anesthetized (ketamine/xylazine) and the vaccines were delivered i.m. in 0.5-mL aliquots into both deltoid muscles using tuberculin syringes (Becton-Dickinson, Franklin Lakes, N.J.). Peripheral blood mononuclear cells (PBMC) were prepared from blood samples collected at several time points during the immunization regimen. All animal care and treatment were in accordance with standards approved by the Institutional Animal Care and Use Committee according to the principles set forth in the Guide for Care and Use of Laboratory Animals, Institute of Laboratory Animal Resources, National Research Council.
B. ELISPOT Assay
The IFN-γ ELISPOT assays for rhesus macaques were conducted following a previously described protocol (Allen et al., 2001 J. Virol. 75(2):738-749), with some modifications. For antigen-specific stimulation, a peptide pool was prepared from 15-aa peptides that encompass the entire HIV-1 gag sequence with 11-aa overlaps (Synpep Corp., Dublin, Calif.). To each well, 50 μL of 2-4×105 peripheral blood mononuclear cells (PBMCs) were added; the cells were counted using Beckman Coulter Z2 particle analyzer with a lower size cut-off set at 80 fL. Either 50 μL of media or the gag peptide pool at 8 μg/mL concentration per peptide was added to the PBMC. The samples were incubated at 37° C., 5% CO2 for 20-24 hrs. Spots were developed accordingly and the plates were processed using custom-built imager and automatic counting subroutine based on the ImagePro platform (Silver Spring, Md.); the counts were normalized to 106 cell input.
C. Results
Two cohorts of 4 rhesus macaques with pre-existing Ad5-specific neutralization were immunized with either (1) 10ˆ10 vp MRKAd5 gag or (2) a mixture of 10ˆ10 vp MRKAd5 gag and 10ˆ10 vp MRKAd6 gag. A control cohort consisting of animals with no pre-existing Ad5 neutralizing activity was given 10ˆ10 vp MRKAd5 gag. Vaccine-induced T cell responses against HIV-1 Gag were quantified using IFN-gamma ELISPOT assay against a pool of 15-aa peptides that encompassed the entire protein sequence. The results are illustrated in
The Gag-specific responses induced by MRKAd5 gag vaccine were attenuated (10-fold at wk 4 and 5-fold at wk 8) in the animals with significant Ad5-specific neutralizing titers prior to immunization relative to the control cohort. Immunization of animals having similar levels of pre-existing Ad5 titer with a mixture of MRKAd5 and MRKAd6 vaccines resulted in improved Gag-specific T cell responses. This is presumably due to the supply of the MRKAd6 component which is not effected by the pre-existing anti-Ad5 titers.
A. Immunization
Rhesus macaques were between 3-10 kg in weight. In all cases, the total dose of each vaccine was suspended in 1 mL of buffer. The macaques were anesthetized (ketamine/xylazine) and the vaccines were delivered i.m. in 0.5-mL aliquots into both deltoid muscles using tuberculin syringes (Becton-Dickinson, Franklin Lakes, N.J.). Peripheral blood mononuclear cells (PBMC) were prepared from blood samples collected at several time points during the immunization regimen. All animal care and treatment were in accordance with standards approved by the Institutional Animal Care and Use Committee according to the principles set forth in the Guide for Care and Use of Laboratory Animals, Institute of Laboratory Animal Resources, National Research Council.
B. ELISPOT Assay
The IFN-γ ELISPOT assays for rhesus macaques were conducted following a previously described protocol (Allen et al., 2001 J. Virol. 75(2):738-749), with some modifications. For antigen-specific stimulation, peptide pools were prepared from 15-aa peptides that encompass the entire HIV-1 nef, gag, and pol sequences with 11-aa overlaps (Synpep Corp., Dublin, Calif.). To each well, 50 ∞L of 2-4×105 peripheral blood mononuclear cells (PBMCs) were added, the cells were counted using Beckman Coulter Z2 particle analyzer with a lower size cut-off set at 80 fL. Either 50 μL of media or the respective peptide pool at 8 μg/mL concentration per peptide was added to the PBMC. The samples were incubated at 37° C., 5% CO2 for 20-24 hrs. Spots were developed accordingly and the plates were processed using custom-built imager and automatic counting subroutine based on the ImagePro platform (Silver Spring, Md.); the counts were normalized to 106 cell input.
C. Results
Cohorts of 3-4 animals were immunized at wk 0, 4 with either 10ˆ10 vp/vector or 10ˆ8 vp/vector dose of one of the following vaccines: (1) MRKAd5 gag+MRKAd5 pol+MRKad5 nef; (2) MRKAd5hCMVnefmCMVgag+MRKAd5 pol; (3) MRKAd5hCMVnef mCMVgagpol; and (4) MRKAd5hCMVgagpolnef. The HIV-specific T cell responses induced by these vaccines at the 10ˆ10 vp/vector dose are listed in
All four vectors were able to induce specific T cell response to all 3 antigens at 10ˆ10 vp/vector dose. While the responses induced by the two-virus or one-virus vaccines appeared to trend lower relative to the three-virus cocktail, the differences were not statistically significant. The immunogenicity of the vaccines at 10ˆ8 vp/vector dose is described in
Even at a lower 10ˆ8 vp/vector dose, all four vectors were able to elicit detectable specific T cell response to all three antigens.
A. Immunization
Rhesus macaques were between 3-10 kg in weight. In all cases, the total dose of each vaccine was suspended in 1 mL of buffer. The macaques were anesthetized (ketamine/xylazine) and the vaccines delivered i.m. in 0.5-mL aliquots into both deltoid muscles using tuberculin syringes (Becton-Dickinson, Franklin Lakes, N.J.). Peripheral blood mononuclear cells (PBMC) were prepared from blood samples collected at several time points during the immunization regimen. All animal care and treatment were in accordance with standards approved by the Institutional Animal Care and Use Committee according to the principles set forth in the Guide for Care and Use of Laboratory Animals, Institute of Laboratory Animal Resources, National Research Council.
B. ELISPOT Assay
The IFN-γ ELISPOT assays for rhesus macaques were conducted following a previously described protocol (Allen et al., 2001 J. Virol. 75(2):738-749), with some modifications. For antigen-specific stimulation, peptide pools were prepared from 15-aa peptides that encompass the entire HIV-1 nef, gag and pol sequences with 11-aa overlaps (Synpep Corp., Dublin, Calif.). To each well, 50 μL of 2-4×105 peripheral blood mononuclear cells (PBMCs) were added; the cells were counted using Beckman Coulter Z2 particle analyzer with a lower size cut-off set at 80 fL. Either 50 μL of media or the respective peptide pool at 8 μg/mL concentration per peptide was added to the PBMC. The samples were incubated at 37° C., 5% CO2 for 20-24 hrs. Spots were developed accordingly and the plates were processed using custom-built imager and automatic counting subroutine based on the ImagePro platform (Silver Spring, Md.); with the counts normalized to 106 cell input.
C. Protocol
Cohorts of 3 macaques were immunized at weeks 0 and 4 with either 10ˆ10 vp/vector or 10ˆ8 vp/vector dose of one of the following vaccines: (1) MRKAd5nefgagpol; (2) MRKAd6nefgagpol; and (3) MRKAd5nefgagpol+MRKAd6nefgagpol. The HIV-specific T cell responses induced by these vaccines at the 10ˆ10 vp/vector dose are listed in
In all three vaccination groups, the vectors were able to induce specific T cell response to all 3 antigens at 10ˆ10 vp/vector dose. The immunogenicity of the Ad5 and Ad6 vectors is comparable when delivered alone or in combination. The immunogenicity of the vaccines at 10ˆ8 vp/vector dose is described in
| Number | Date | Country | Kind |
|---|---|---|---|
| 60/600328 | Aug 2004 | US | national |
The present application claims the benefit of U.S. Provisional Application No. 60/600,328 filed Aug. 9, 2004, which is hereby incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US05/27658 | 8/5/2005 | WO | 2/7/2007 |
