Patent Application
20120128713
This invention relates to replication-defective flavivirus vaccine vectors against respiratory syncytial virus (RSV), and corresponding compositions and methods.
Flaviviruses are distributed worldwide and represent a global public health problem. Flaviviruses also have a significant impact as veterinary pathogens. Flavivirus pathogens include yellow fever (YF), dengue types 1-4 (DEN1-4), Japanese encephalitis (JE), West Nile (WN), tick-borne encephalitis (TBE), and other viruses from the TBE serocomplex, such as Kyasanur Forest disease (KFD) and Omsk hemorrhagic fever (OHF) viruses. Vaccines against YF [live attenuated vaccine (LAV) strain 17D], JE [inactivated vaccines (INV) and LAV], and TBE (INV) are available. No licensed human vaccines are currently available against DEN and WN. Veterinary vaccines have been in use including, for example, vaccines against WN in horses (INV, recombinant and live chimeric vaccines), JE (INV and LAV) to prevent encephalitis in horses and stillbirth in pigs in Asia, louping ill flavivirus (NV) to prevent neurologic disease in sheep in the UK, and TBE (NV) used in farm animals in Czech Republic (NV) (Monath and Heinz, Flaviviruses, in Fields et al. Eds., Fields Virology, 3rd Edition, Philadelphia, New York, Lippincott-Raven Publishers, 1996, pp. 961-1034).
Flaviviruses are small, enveloped, plus-strand RNA viruses transmitted primarily by arthropod vectors (mosquitoes or ticks) to natural hosts, which are primarily vertebrate animals, such as various mammals, including humans, and birds. The flavivirus genomic RNA molecule is about 11,000 nucleotides (nt) in length and encompasses a long open reading frame (ORF) flanked by 5′ and 3′ untranslated terminal regions (UTRs) of about 120 and 500 nucleotides in length, respectively. The ORF encodes a polyprotein precursor that is cleaved co- and post-translationally to generate individual viral proteins. The proteins are encoded in the order: C-prM/M-E-NS1-NS2A/2B-NS3-NS4A/4B-NS5, where C (core/capsid), prM/M (pre-membrane/membrane), and E (envelope) are the structural proteins, i.e., the components of viral particles, and the NS proteins are non-structural proteins, which are involved in intracellular virus replication. Flavivirus replication occurs in the cytoplasm. Upon infection of cells and translation of genomic RNA, processing of the polyprotein starts with translocation of the prM portion of the polyprotein into the lumen of endoplasmic reticulum (ER) of infected cells, followed by translocation of E and NS1 portions, as directed by the hydrophobic signals for the prM, E, and NS1 proteins Amino-termini of prM, E, and NS1 proteins are generated by cleavage with cellular signalase, which is located on the luminal side of the ER membrane, and the resulting individual proteins remain carboxy-terminally anchored in the membrane. Most of the remaining cleavages, in the nonstructural region, are carried out by the viral NS2B/NS3 serine protease. The viral protease is also responsible for generating the C-terminus of the mature C protein found in progeny virions. Newly synthesized genomic RNA molecules and the C protein form a dense spherical nucleocapsid, which becomes surrounded by cellular membrane in which the E and prM proteins are embedded. The mature M protein is produced by cleavage of prM shortly prior to virus release by cellular furin or a similar protease. E, the major protein of the envelope, is the principal target for neutralizing antibodies, the main correlate of immunity against flavivirus infection. Virus-specific cytotoxic T-lymphocyte (CTL) response is the other key attribute of immunity. Multiple CD8+ and CD4+ CTL epitopes have been characterized in various flavivirus structural and non-structural proteins. In addition, innate immune responses contribute to both virus clearance and regulating the development of adaptive immune responses and immunologic memory.
In addition to the inactivated (INV) and live-attenuated (LAV) vaccines against flaviviruses discussed above, other vaccine platforms have been developed. One example is based on chimeric flaviviruses that include yellow fever virus capsid and non-structural sequences and prM-E proteins from other flaviviruses, to which immunity is sought. This technology has been used to develop vaccine candidates against dengue (DEN), Japanese encephalitis (JE), West Nile (WN), and St. Louis encephalitis (SLE) viruses (see, e.g., U.S. Pat. Nos. 6,962,708 and 6,696,281). Yellow fever virus-based chimeric flaviviruses have yielded highly promising results in clinical trials.
Another flavivirus vaccine platform is based on the use of pseudoinfectious virus (PIV) technology (Mason et al., Virology 351:432-443, 2006; Shustov et al., J. Virol. 21:11737-11748, 2007; Widman et al., Adv. Virus. Res. 72:77-126, 2008; Suzuki et al., J. Virol. 82:6942-6951, 2008; Suzuki et al., J. Virol. 83:1870-1880, 2009; Ishikawa et al., Vaccine 26:2772-2781, 2008; Widman et al., Vaccine 26:2762-2771, 2008). PIVs are replication-defective viruses attenuated by a deletion(s). Unlike live flavivirus vaccines, they undergo a single round replication in vivo (or optionally limited rounds, for two-component constructs; see below), which may provide benefits with respect to safety. PIVs also do not induce viremia and systemic infection. Further, unlike inactivated vaccines, PIVs mimic whole virus infection, which can result in increased efficacy due to the induction of robust B- and T-cell responses, higher durability of immunity, and decreased dose requirements. Similar to whole viruses, PIV vaccines target antigen-presenting cells, such as dendritic cells, stimulate toll-like receptors (TLRs), and induce balanced Th1/Th2 immunity. In addition, PIV constructs have been shown to grow to high titers in substrate cells, with little or no cytopathic effect (CPE), allowing for high-yield manufacture, optionally employing multiple harvests and/or expansion of infected substrate cells.
The principles of the PIV technology are illustrated in
In the second variation, a two-component PIV (d-PIV) is constructed (
Respiratory syncytial virus (RSV) is a negative-sense, single-stranded RNA virus of the family Paramyxoviridae. Its name is based on the activity of the RSV fusion or F glycoprotein, which is on the surface of the virus and causes cell membranes of infected cells to merge, resulting in the formation of syncytia. RSV infects the respiratory tract, and is the major cause of lower respiratory tract infections (including pneumonia) and hospital visits during infancy and childhood. For example, in the United States, 60% of infants are infected during their first RSV season, and nearly all children will have been infected by 2-3 years of age (Glezen et al., Am. J. Dis. Child. 140(6):543-546, 1986). Of those infected, 2-3% will develop bronchiolitis, or inflammation of the small airways in the lung, and require hospitalization (Hall et al., N. Engl. J. Med. 360(6):588-598, 2009). Further, RSV infection is increasingly being found as an infection of the elderly. Current treatment is generally focused on supportive care, including administration of fluids and oxygen.
The invention provides replication-deficient pseudoinfectious flaviviruses that each include a flavivirus genome including (i) one or more deletions or mutations in nucleotide sequences encoding one or more proteins selected from the group consisting of capsid (C), pre-membrane (prM), envelope (E), non-structural protein 1 (NS1), non-structural protein 3 (NS3), and non-structural protein 5 (NS5), and (ii) a sequence encoding a respiratory syncytial virus (RSV) peptide or protein, or a fragment or analog thereof. As described elsewhere herein, the vectors of the invention are replication deficient due to the one or more deletions or mutations, and can be complemented in trans (see below for details). Any of the deletions/mutations described herein, as well as other deletions/mutations resulting in replication deficiency, can be used in the vectors of the invention.
In one embodiment, the respiratory syncytial virus (RSV) protein is the RSV F protein, or a fragment or analog thereof. In various examples, the RSV F protein lacks a trans-membrane domain, e.g., it is truncated so that it is produced in secreted form. In other examples, the respiratory syncytial virus (RSV) protein is the RSV G protein, or a fragment or analog thereof.
In various embodiments, the one or more deletions or mutations is within capsid (C) sequences of the flavivirus genome; is within pre-membrane (prM) and/or envelope (E) sequences of the flavivirus genome; is within capsid (C), pre-membrane (prM), and envelope (E) sequences of the flavivirus genome; and/or is within non-structural protein 1 (NS1) sequences of the flavivirus genome. In other examples, the flavivirus genome includes sequences encoding a pre-membrane (prM) and/or envelope (E) protein.
The flavivirus genome of the replication-deficient pseudoinfectious flaviviruses can be, for example, selected from that of yellow fever virus, West Nile virus, tick-borne encephalitis virus, Langat virus, Japanese encephalitis virus, dengue virus (1-4), and St. Louis encephalitis virus sequences, and chimeras thereof (also see below). In certain examples, the chimeras include pre-membrane (prM) and envelope (E) sequences of a first flavivirus, and capsid (C) and non-structural sequences of a second, different flavivirus. In other examples, the genome is packaged in a particle including pre-membrane (prM) and envelope (E) sequences from a flavivirus that is the same or different from that of the genome. Further, sequences encoding the RSV protein can be inserted in the place of or in combination with the one or more deletions or mutations of the one or more proteins.
In certain examples, sequences encoding the respiratory syncytial virus peptide or protein, or a fragment or analog thereof, are inserted in the flavivirus genome within sequences encoding the envelope (E) protein, within sequences encoding the non-structural 1 (NS1) protein, within sequences encoding the pre-membrane (prM) protein, intergenically between sequences encoding the envelope (E) protein and non-structural protein 1 (NS1), intergenically between non-structural protein 2B (NS2B) and non-structural protein 3 (NS3), or as a bicistronic insertion in the 3′ untranslated region of the flavivirus genome.
The invention also includes pharmaceutical compositions including one or more of the replication-deficient pseudoinfectious flaviviruses described above and elsewhere herein. Compositions of the invention can also a pharmaceutically acceptable carrier or diluent, and, optionally, an adjuvant.
Other compositions of the invention include a first replication-deficient pseudoinfectious flavivirus, such as one of those described above and elsewhere herein, and a second, different replication-deficient pseudoinfectious flavivirus including a genome having one or more deletions or mutations in nucleotide sequences encoding one or more proteins selected from the group consisting of capsid (C), pre-membrane (prM), envelope (E), non-structural protein 1 (NS1), non-structural protein 3 (NS3), and non-structural protein 5 (NS5), wherein the one or more proteins encoded by the sequences in which the one or more deletion(s) or mutation(s) occur in the second, different replication-deficient pseudoinfectious flavivirus are different from the one or more proteins encoded by the sequences in which the one or more deletion(s) or mutation(s) occur in the first replication-deficient pseudoinfectious flavivirus.
The invention also provides methods of inducing an immune response to respiratory syncytial virus (RSV) in a subject, involving administering to the subject one or more replication-deficient pseudoinfectious flaviviruses or a composition as described above and elsewhere herein. The subject may be at risk of but not have an infection by respiratory syncytial virus (RSV), or the subject may have an infection by respiratory syncytial virus (RSV). In certain examples, the subject is an infant, young child, or elderly person. The methods of the invention can be for inducing an immune response against a protein encoded by the flavivirus genome, in addition to RSV. In such methods, the subject may be at risk of but does not have an infection by the flavivirus corresponding to the genome of the pseudoinfectious flavivirus, which includes sequences encoding a flavivirus pre-membrane and/or envelope protein. In another example, the subject has an infection by the flavivirus corresponding to the genome of the pseudoinfectious flavivirus, which includes sequences encoding a flavivirus pre-membrane and/or envelope protein.
Also included in the invention are nucleic acid molecules corresponding to the genomes of pseudoinfectious flaviviruses as described herein and complements thereof.
The invention also provides methods of making a replication-deficient pseudoinfectious flavivirus as described herein. These methods involve introducing a nucleic acid molecule as described above into a cell that expresses the protein corresponding to any sequences deleted from the flavivirus genome of the replication-deficient pseudoinfectious flavivirus. The protein can be expressed in the cell from, for example, the genome of a second, different, replication-deficient pseudoinfectious flavivirus. In various examples, the protein is expressed from a replicon (e.g., an alphavirus replicon, such as a Venezuelan Equine Encephalitis virus replicon).
By “replication-deficient pseudoinfectious flavivirus” or “PIV” is meant a flavivirus that is replication-deficient due to a deletion or mutation in the flavivirus genome. The deletion or mutation can be, for example, a deletion of a large sequence, such as most of the capsid protein, as described herein (with the cyclization sequence remaining; see below). In other examples, sequences encoding different proteins (e.g., prM, E, NS1, NS3, and/or NS5; see below) or combinations of proteins (e.g., prM-E or C-prM-E) are deleted. This type of deletion may be advantageous for use of the PIV as a vector to deliver a heterologous immunogen, as the deletion can permit insertion of sequences that may be, for example, at least up to the size of the deleted sequence. In other examples, the mutation can be, for example, a point mutation, provided that it results in replication deficiency, as discussed above. Because of the deletion or mutation, the genome does not encode all proteins necessary to produce a full flavivirus particle. The missing sequences can be provided in trans by a complementing cell line that is engineered to express the missing sequence (e.g., by use of a replicon; s-PIV; see below), or by co-expression of two replication-deficient genomes in the same cell, where the two replication-deficient genomes, when considered together, encode all proteins necessary for production (d-PIV system; see below).
Upon introduction into cells that do not express complementing proteins, the genomes replicate and, in some instances, generate “virus-like particles,” which are released from the cells and are able to leave the cells and be immunogenic, but cannot infect other cells and lead to the generation of further particles. For example, in the case of a PIV including a deletion in capsid protein encoding sequences, after infection of cells that do not express capsid, VLPs including prM-E proteins are released from the cells. Because of the lack of capsid protein, the VLPs lack capsid and a nucleic acid genome. In the case of the d-PIV approach, production of further PIVs is possible in cells that are infected with two PIVs that complement each other with respect to the production of all required proteins (see below).
The invention provides several advantages. For example, the PIV vectors and PIVs of the invention are highly attenuated and highly efficacious after one-to-two doses, providing durable immunity. Further, unlike inactivated vaccines, PIVs mimic whole virus infection, which can result in increased efficacy due to the induction of robust B- and T-cell responses, higher durability of immunity, and decreased dose requirements. In addition, similar to whole viruses, PIV vaccines target antigen-presenting cells, such as dendritic cells, stimulate toll-like receptors (TLRs), and induce balanced Th1/Th2 immunity. PIV constructs have also been shown to grow to high titers in substrate cells, with little or no CPE, allowing for high-yield manufacture, optionally employing multiple harvests and/or expansion of infected substrate cells. Further, the PIV vectors of the invention provide an option for developing vaccines against non-flavivirus pathogens, such as RSV, for which no vaccines are currently available.
Other features and advantages of the invention will be apparent from the following detailed description, the drawings, and the claims.
The invention provides replication-defective or deficient pseudoinfectious virus (PIV) vectors including flavivirus sequences, which can be used in methods for inducing immunity against heterologous immunogens inserted into the vectors as well as, optionally, the vectors themselves. The invention also includes compositions including combinations of PIVs and/or Ply vectors, as described herein, and methods of using such compositions to induce immune responses against inserted immunogen sequences and/or sequences of the PIVs themselves. The focus of the invention is PIV vectors containing respiratory syncytial virus (RSV) immunogens, such as F or G protein immunogens, in one embodiment (see, e.g., truncated F protein, below). These vectors can be used in methods to prevent or treat RSV infection, and also in combination methods involving use of, for example, any of the other vectors described herein (such as vectors including immunogens of other pathogens and/or cancer, and/or allergy-related immunogens). The vectors, compositions, and methods of the invention are described further below.
The PIV vectors of the invention can be based on the single- or two-component PIVs described above (also see WO 2007/098267 and WO 2008/137163). Thus, for example, in the case of single component PIVs, the PIV vectors and PIVs can include a genome including a large deletion in capsid protein encoding sequences and be produced in a complementing cell line that produces capsid protein in trans (single component;
Single component PIV vectors and PIVs can be propagated in cell lines that express either C or a C-prM-E cassette, where they replicate to high levels. Exemplary cell lines that can be used for expression of single component PIV vectors and PIVs include BHK-21 (e.g., ATCC CCL-10), Vero (e.g., ATCC CCL-81), C7/10, and other cells of vertebrate or mosquito origin. The C or C-prM-E cassette can be expressed in such cells by use of a viral vector-derived replicon, such as an alphavirus replicon (e.g., a replicon based on Venezuelan Equine Encephalitis virus (VEEV), Sindbis virus, Semliki Forest virus (SFV), Eastern Equine Encephalitis virus (EEEV), Western Equine Encephalitis virus (WEEV), or Ross River virus). To decrease the possibility of productive recombination between the PIV vectors/PIVs and complementing sequences, the sequences in the replicons (encoding C, prM, and/or E) can include nucleotide mutations. For example, sequences encoding a complementing C protein can include an unnatural cyclization sequence. The mutations can result from codon optimization, which can provide an additional benefit with respect to PIV yield. Further, in the case of complementing cells expressing C protein sequences (and not a C-prM-E cassette), it may be beneficial to include an anchoring sequence at the carboxy terminus of the C protein including, for example, about 20 amino acids of prM (see, e.g., WO 2007/098267).
The PIV vectors and PIVs of the invention can also be based on the two-component genome technology described above. This technology employs two partial genome constructs, each of which is deficient in expression of at least one protein required for productive replication (capsid or prM/E) but, when present in the same cell, result in the production of all components necessary to make a PIV. Thus, in one example of the two-component genome technology, the first component includes a large deletion of C, as described above in reference to single component PIVs, and the second component includes a deletion of prM and E (
Additional examples of d-PIV approaches that can be used in the invention are based on use of complementing genomes including deletions in NS3 or NS5 sequences. A deletion in, e.g., NS1, NS3, or NS5 proteins can be used as long as several hundred amino acids in the ORF, removing the entire chosen protein sequence, or as short as 1 amino acid inactivating protein enzymatic activity (e.g., NS5 RNA polymerase activity, NS3 helicase activity, etc.). Alternatively, point amino acid changes (as few as 1 amino acid mutation, or optionally more mutations) can be introduced into any NS protein, inactivating enzymatic activity. In addition, several ΔNS deletions can be combined in one helper molecule. The same heterologous gene (such as an RSV F or G protein (e.g., truncated RSV F protein) gene), i.e., expressed by the first d-PIV component, can be expressed in place or in combination with the NS deletion(s) in the second component, increasing the amount of expressed immunogen. Notably, the insertion capacity of the helper will increase proportionally to the size of NS deletion(s). Alternatively, a different foreign immunogen(s) can be inserted in place of deletion(s) of the helper to produce multivalent vaccines.
Further, additional approaches that can be used in making PIV vectors and PIVs for use in the present invention are described, for example, in WO 99/28487, WO 03/046189, WO 2004/108936, US 2004/0265338, US 2007/0249032, and U.S. Pat. No. 7,332,322.
The PIV vectors of the invention can be comprised of sequences from a single flavivirus type (e.g., West Nile, tick-borne encephalitis (TBE, e.g., strain Hypr), Langat (LGT), yellow fever (e.g., YF17D), Japanese encephalitis, dengue (serotype 1-4), St. Louis encephalitis, Kunjin, Rocio encephalitis, Ilheus, Central European encephalitis, Siberian encephalitis, Russian Spring-Summer encephalitis, Kyasanur Forest Disease, Omsk Hemorrhagic fever, Louping ill, Powassan, Negishi, Absettarov, Hansalova, and Apoi viruses), or can comprise sequences from two or more different flaviviruses. Sequences of some strains of these viruses are readily available from generally accessible sequence databases; sequences of other strains can be easily determined by methods well known in the art. In the case of PIV vectors and PIVs including sequences of more than one flavivirus, the sequences can be those of a chimeric flavivirus, as described above (also see, e.g., U.S. Pat. No. 6,962,708; U.S. Pat. No. 6,696,281; and U.S. Pat. No. 6,184,024). In certain examples, the chimeras include pre-membrane and envelope sequences from one flavivirus (such as a flavivirus to which immunity may be desired), and capsid and non-structural sequences from a second, different flavivirus. In one specific example, the second flavivirus is a yellow fever virus, such as the vaccine strain YF17D. Other examples include the YF/WN, YF/TBE, YF/LGT, WN/TBE, and WN/LGT chimeras described below. Another example is an LGT/TBE chimera based on LGT virus backbone containing TBE virus prM-E proteins. A PIV vaccine based on this genetic background would have an advantage, because LGT replicates very efficiently in vitro and is highly attenuated and immunogenic for humans. Thus, a chimeric LGT/TBE PIV vaccine is expected to provide a robust specific immune response in humans against TBE, particularly due to inclusion of TBE prM-E genes.
Vectors of the invention can be based on PIV constructs or live, attenuated chimeric flaviviruses as described herein (in particular, YF/TBE, YF/LGT, WN/TBE, and WN/LGT; see below). Use of PIV constructs as vectors provides particular advantages in certain circumstances, because these constructs by necessity include large deletions, which render the constructs amenable to accommodation of insertions that are at least up to the size of the deleted sequences, without there being a loss in replication efficiency. Thus, PIV vectors in general can comprise very small insertions (e.g., in the range 6-10, 11-20, 21-100, 101-500, or more amino acid residues combined with the AC deletion or other deletions), as well as relatively large insertions or insertions of intermediate size (e.g., in the range 501-1000, 1001-1700, 1701-3000, or 3001-4000 or more residues). In contrast, in certain examples, it may be advantageous to express relatively short sequences in live attenuated viruses, particularly if the insertions are made in the absence of a corresponding deletion. Additional information concerning insertion sites that can be used in the invention is provided below. In addition, as discussed further below, expression of non-flavivirus immunogens in PIVs and chimeric flaviviruses of the invention can result in dual vaccines that elicit protective immunity against both a flavivirus vector virus pathogen and a target heterologous immunogen (e.g., RSV immunogens, such as those described herein).
As discussed above, the PIV vectors and PIVs of the invention can comprise sequences of chimeric flaviviruses, for example, chimeric flaviviruses including pre-membrane and envelope sequences of a first flavivirus (e.g., a flavivirus to which immunity is sought), and capsid and non-structural sequences of a second, different flavivirus, such as a yellow fever virus (e.g., YF17D; see above and also U.S. Pat. No. 6,962,708; U.S. Pat. No. 6,696,281; and U.S. Pat. No. 6,184,024). Further, chimeric flaviviruses (as well as non-chimeric flaviviruses, e.g., West Nile virus) used in the invention, used as a source for constructing PIVs, can optionally include one or more specific attenuating mutations (e.g., E protein mutations, prM protein mutations, deletions in the C protein, and/or deletions in the 3′UTR), such as any of those described in WO 2006/116182. For example, the C protein or 3′UTR deletions can be directly applied to YF/WN, YF/TBE, or YF/LGT chimeras Similar deletions can be designed and introduced in other chimeric LAV candidates such as based on LGT/TBE, WN/TBE, and WN/LGT genomes. With respect to E protein mutations, attenuating mutations similar to those described for YF/WN chimera in WO 2006/116182 can be designed, e.g., based on the knowledge of crystal structure of the E protein (Rey et al., Nature 375(6529):291-298, 1995), and employed. Further, additional examples of attenuating E protein mutations described for TBE virus and other flaviviruses are provided in Table 9. These can be similarly introduced into chimeric vaccine candidates.
The invention also provides new, particular chimeric flaviviruses, which can be used as a basis for the design of PIV vectors and PIVs, and as live attenuated chimeric flavivirus vectors. These chimeras include tick-borne encephalitis (TBE) virus or related prM-E sequences. Thus, the chimeras can include prM-E sequences from, for example, the Hypr strain of TBE or Langat (LGT) virus. Capsid and non-structural proteins of the chimeras can include those from yellow fever virus (e.g., YF17D) or West Nile virus (e.g., NY99).
A central feature of these exemplary YF/TBE, YF/LGT, WN/TBE, and WN/LGT chimeras is the signal sequence between the capsid and prM proteins. As is shown in the Examples, below, we have found that, in the case of YF-based PIV chimeras, it is advantageous to use a signal sequence comprising yellow fever and TBE sequences (see below). In one example, the signal sequence includes yellow fever sequences in the amino terminal region (e.g., SHDVLTVQFLIL) and TBE sequences in the carboxy terminal region (e.g., GMLGMTIA), resulting in the sequence SHDVLTVQFLILGMLGMTIA. We have also found that, in the case of WN-based PIV chimeras, it is advantageous to use a signal sequence comprising TBE sequences (e.g., GGTDWMSWLLVIGMLGMTIA). The invention thus includes YF/TBE, YF/LGT, WN/TBE, and WN/LGT chimeras, both PIVs and LAVs, which include the above-noted signal sequences, or variants thereof having, e.g., 1-8, 2-7, 3-6, or 4-5 amino acid substitutions, deletions, or insertions, which do not substantially interfere with processing at the signal sequence. In various examples, the substitutions are “conservative substitutions,” which are characterized by replacement of one amino acid residue with another, biologically similar residue. Examples of conservative substitutions include the substitution of one hydrophobic residue such as isoleucine, valine, leucine, or methionine for another, or the substitution of one polar residue for another, such as between arginine and lysine, between glutamic and aspartic acids, or between glutamine and asparagine and the like. Additional information concerning these chimeras is provided below, in the Examples.
Sequences encoding immunogens can be inserted at one or more different sites within the vectors of the invention. Relatively short peptides can be delivered on the surface of PIV or LAV glycoproteins (e.g., prM, E, and/or NS1 proteins) and/or in the context of other proteins (to induce predominantly B-cell and T-cell responses, respectively). Other inserts, including larger portions of foreign proteins (e.g., certain RSV F or G protein sequences, as described herein), as well as complete proteins, can be expressed intergenically, at the N- and C-termini of the polyprotein, or bicistronically (e.g., within the ORF under an IRES or in the 3′UTR under an IRES; see, e.g., WO 02/102828, WO 2008/036146, WO 2008/094674, WO 2008/100464, WO 2008/115314, and below for further details). In PIV constructs, there is an additional option of inserting a foreign amino acid sequence directly in place of introduced deletion(s). Insertions can be made in, for example, AC, AprM-E, AC-prM-E, ANSI, ANS3, and ANS5. Thus, in one example, in the case of s-PIVs and the AC component of d-PIVs, immunogen-encoding sequences can be inserted in place of deleted capsid sequences. Immunogen-encoding sequences can also, optionally, be inserted in place of deleted prM-E sequences in the AprM-E component of d-PIVs. In another example, the sequences are inserted in place of or combined with deleted sequences in AC-prM-E constructs. Examples of such insertions are provided in the Examples section, below.
In the case of making insertions into PIV deletions, the insertions can be made with a few (e.g., 1, 2, 3, 4, or 5) additional vector-specific residues at the N- and/or C-termini of the foreign immunogen, if the sequence is simply fused in-frame (e.g., ˜20 first a.a. and a few last residues of the C protein if the sequence replaces the AC deletion), or without, if the foreign immunogen is flanked by appropriate elements well known in the field (e.g., viral protease cleavage sites; cellular protease cleavage sites, such as signalase, furin, etc.; autoprotease; termination codon; and/or IRES elements).
If a protein is expressed outside of the continuous viral open reading frame (ORF), e.g., if vector and non-vector sequences are separated by an internal ribosome entry site (IRES), cytoplasmic expression of the product can be achieved or the product can be directed towards the secretory pathway by using appropriate signal/anchor segments, as desired. If the protein is expressed within the vector ORF, important considerations include cleavage of the foreign protein from the nascent polyprotein sequence, and maintaining correct topology of the foreign protein and all viral proteins (to ensure vector viability) relative to the ER membrane, e.g., translocation of secreted proteins into the ER lumen, or keeping cytoplasmic proteins or membrane-associated proteins in the cytoplasm/in association with the ER membrane.
In more detail, the above-described approaches to making insertions can employ the use of, for instance, appropriate vector-derived, insert-derived, or unrelated signal and anchor sequencess included at the N and C termini of glycoprotein inserts. Standard autoproteases, such as FMDV 2A autoprotease (˜20 amino acids) or ubiquitin (gene ˜500 nt), or flanking viral NS2B/NS3 protease cleavage sites can be used to direct cleavage of an expressed product from a growing polypeptide chain, to release a foreign protein from a vector polyprotein, and to ensure viability of the construct. Optionally, growth of the polyprotein chain can be terminated by using a termination codon, e.g., following a foreign gene insert, and synthesis of the remaining proteins in the constructs can be re-initiated by incorporation of an IRES element, e.g., the encephalomyocarditis virus (EMCV) IRES commonly used in the field of RNA virus vectors. Viable recombinants can be recovered from helper cells (or regular cells for d-PIV versions). Optionally, backbone PIV sequences can be rearranged, e.g., if the latter results in more efficient expression of a foreign gene. For example, a gene rearrangement has been applied to TBE virus, in which the prM-E genes were moved to the 3′ end of the genome under the control of an IRES (Orlinger et al., J. Virol. 80:12197-12208, 2006). Translocation of prM-E or any other genes can be applied to PIV flavivirus vaccine candidates and expression vectors, according to the invention.
Additional details concerning different insertion sites that can be used in the invention are as follows (also see WO 02/102828, WO 2008/036146, WO 2008/094674, WO 2008/100464, WO 2008/115314, as noted above). Peptide sequences can be inserted within the envelope protein, which is the principle target for neutralizing antibodies. The sequences can be inserted into the envelope in, for example, positions corresponding to amino acid positions 59, 207, 231, 277, 287, 340, and/or 436 of the Japanese encephalitis virus envelope protein (see, e.g., WO 2008/115314 and WO 02/102828). To identify the corresponding loci in different flaviviruses, the flavivirus sequences are aligned with that of Japanese encephalitis virus. As there may not be an exact match, it should be understood that, in non-JE viruses, the site of insertion may vary by, for example, 1, 2, 3, 4, or 5 amino acids, in either direction. Further, given the identification of such sites as being permissive in JE, they can also vary in JE by, for example, 1, 2, 3, 4, or 5 amino acids, in either direction. Additional permissive sites can be identified using methods such as transposon mutagenesis (see, e.g., WO 02/102828 and WO 2008/036146). The insertions can be made at the indicated amino acids by insertion just C-terminal to the indicated amino acids (i.e., between amino acids 51-52, 207-208, 231-232, 277-278, 287-288, 340-341, and 436-437), or in place of short deletions (e.g., deletions of 1, 2, 3, 4, 5, 6, 7, or 8 amino acids) beginning at the indicated amino acids (or within 1-5 positions thereof, in either direction).
In addition to the envelope protein, insertions can be made into other virus proteins including, for example, the membrane/pre-membrane protein and NS1 (see, e.g., WO 2008/036146). For example, insertions can be made into a sequence preceding the capsid/pre-membrane cleavage site (at, e.g., −4, −2, or −1) or within the first 50 amino acids of the pre-membrane protein (e.g., at position 26), and/or between amino acids 236 and 237 of NS1 (or in regions surrounding the indicated sequences, as described above). In other examples, insertions can be made intergenically. For example, an insertion can be made between E and NS1 proteins and/or between NS2B and NS3 proteins (see, e.g., WO 2008/100464). In one example of an intergenic insertion, the inserted sequence can be fused with the C-terminus of the E protein of the vector, after the C-terminal signal/anchor sequence of the E protein, and the insertion can include a C-terminal anchor/signal sequence, which is fused with vector NS1 sequences. In another example of an intergenic insertion, the inserted sequences, with flanking protease cleavage sites (e.g., YF 17D cleavage sites), can be inserted into a unique restriction site introduced at the NS2B/NS3 junction (WO 2008/100464).
In other examples, a sequence can be inserted in the context of an internal ribosome entry site (IRES, e.g., an IRES derived from encephalomyocarditis virus; EMCV), as noted above, such as inserted in the 3′-untranslated region (WO 2008/094674). In one example of such a vector, employing, for example, yellow fever virus sequences, an IRES-immunogen cassette can be inserted into a multiple cloning site engineered into the 3′-untranslated region of the vector, e.g., in a deletion (e.g., a 136 nucleotide deletion in the case of a yellow fever virus-based example) after the polyprotein stop codon (WO 2008/094674).
Details concerning the insertion of rabies virus G protein and respiratory syncytial virus (RSV) F protein (including truncated F) into s-PIV and d-PIV vectors of the invention are provided below in Example 3. The information provided in Example 3 can be applied in the context of other vectors and immunogens described herein.
PIVs (s-PIVs and d-PIVs) based on flavivirus sequences and live, attenuated chimeric flaviviruses (e.g., YF/WN, YF/TBE, YF/LGT, WN/TBE, and WN/LGT), as described above, can be used in the invention to deliver foreign (e.g., non-flavivirus) pathogen immunogens. The focus of the invention is the delivery of RSV immunogens, such as RSV fusion or F protein (or RSV G) immunogens (e.g., truncated F proteins; see below, for example the truncated F protein sequence in Example 3). PIVs and chimeric flavivirus vectors delivering a particular RSV immunogen can, optionally, be delivered with vectors delivering one or more other RSV immunogens, or one or more immunogens from another pathogen (e.g., viral, bacterial, fungal, and parasitic pathogens), one or more immunogens from cancer, and/or allergy-related immunogens. Specific, non-limiting examples of immunogens that can be delivered according to the invention are provided as follows.
As noted above, a central focus of the invention is delivery of the RSV proteins such as, in one embodiment, the RSV fusion or F glycoprotein and, in particular, truncated forms of this protein. The RSV F glycoprotein is one of the major immunogenic proteins of the virus. It is an envelope glycoprotein that mediates both fusion of the virus to the host cell membrane, and cell-to-cell spread of the virus. The amino acid sequence of the F protein is highly conserved among RSV subgroups A and B and is a cross-protective antigen.
RSV F protein comprises an extracellular region, a trans-membrane region, and a cytoplasmic tail region. A truncated protein delivered according to the invention can be, for example, one in which the trans-membrane and cytoplasmic tail regions of the F protein are absent (see, e.g., Example 3, below). Lack of expression of the trans-membrane region results in a secreted form of the RSV protein.
RSV F protein, as used herein, includes both full-length and truncated RSV fusion proteins, which may have the sequences described herein, or have variations in their amino acid sequences including naturally occurring in various strains of RSV and those introduced by PCR amplification of the encoding gene while retaining the immunogenic properties, a secreted form of the RSV F protein lacking a trans-membrane anchor and cytoplasmic tail, as well as fragments capable of generating antibodies which specifically react with RSV F protein and functional analogs. A first protein is a functional analog of a second protein if the first protein is immunologically related to and/or has the same function as the second protein. It may be for example, a fragment of the protein, or a substitution, addition, or deletion mutant thereof. The RSV F glycoprotein can be from, e.g., subgroup A or B (Wertz et al., Biotechnology 20:151-176, 1992).
In a further embodiment of the present invention, RSV G glycoprotein can be delivered. The G protein is a approximately 33 kDa protein and is heavily O-glycosylated, giving rise to a glycoprotein having a molecular weight of about 90 kDa (Levine, S., Kleiber-France, R., and Paradiso, P. R. (1987) J. Gen. Virol. 69, 2521-2524). The 298 amino acid residue RSV G protein belongs to the type II glycoproteins with the transmembrane domain (TM) located near the N-terminus (putative location: residues 38 to 66 underlined in Sequence Appendix 7. The RSV F and G proteins, or fragments or analogs thereof, can be from, for example, group A (e.g., A1 or A2) or B RSV.
Other examples of immunogens that can be delivered according to the invention are protective immunogens of the causative agent of Lyme disease (tick-borne spirochete Borrelia burgdorferi). In one example, PIVs including TBE/LGT sequences, as well as chimeric flaviviruses including TBE sequences (e.g., YF/TBE, YF/LGT, WN/TBE, LGT/TBE, and WN/LGT; in all instances where “TBE” is indicated, this includes the option of using the Hypr strain), can be used as vectors to deliver these immunogens. This combination, targeting both infectious agents (TBE and B. burgdorferi) is advantageous, because TBE and Lyme disease are both tick-borne diseases. The PIV approaches can be applied to chimeras (e.g., YF/TBE, YF/LGT, WN/TBE, or WN/LGT), according to the invention, as well as to non-chimeric TBE and LGT viruses. An exemplary immunogen from B. burgdorferi that can be used in the invention is OspA (Gipson et al., Vaccine 21:3875-3884, 2003). Optionally, to increase safety and/or immunogenicity, OspA can be mutated to reduce chances of autoimmune responses and/or to eliminate sites for unwanted post-translational modification in vertebrate animal cells, such as N-linked glycosylation, which may affect immunogenicity of the expression product. Mutations that decrease autoimmunity can include, e.g., those described by Willett et al., Proc. Natl. Acad. Sci. U.S.A. 101:1303-1308, 2004. In one example, FTK-OspA, a putative cross-reactive T cell epitope, Bb OspA165-173 (YVLEGTLTA) is altered to resemble the corresponding peptide sequence of Borrelia afzelli (FTLEGKVAN). In FTK-OspA, the corresponding sequence is FTLEGKLTA.
The sequence of OspA is as follows:
The full-length sequence and/or immunogenic fragments of the full-length sequence can be used. Exemplary fragments can include one or more of domains 1 (amino acids 34-41), 2 (amino acids 65-75), 3 (amino acids 190-220), and 4 (amino acids 250-270) (Jiang et al., Clin. Diag. Lab. Immun. 1(4):406-412, 1994). Thus, for example, a peptide comprising any one (or more) of the following sequences (which include sequence variations that can be included in the sequence listed above, in any combination) can be delivered: LPGE/GM/IK/T/GVL; GTSDKN/S/DNGSGV/T; N/H/EIS/P/L/A/SK/NSGEV/IS/TV/AE/ALN/DDT/SD/NS/TS/TA/Q/RATKKTA/GA/K/TWN/DS/AG/N/KT; SN/AGTK/NLEGS/N/K/TAVEIT/KK/TLD/KEI/LKN.
In addition to B. burgdorferi immunogens, tick saliva proteins, such as 64TRP, Isac, and Salp20, can be expressed, e.g., to generate a vaccine candidate of trivalent-specificity (TBE+Lyme disease+ticks). Alternatively, tick saliva proteins can be expressed instead of B. burgdorferi immunogens in TBE sequence-containing vectors. In addition, there are many other candidate tick saliva proteins that can be used for tick vector vaccine development according to the invention (Francischetti et al., Insect Biochem. Mol. Biol. 35:1142-1161, 2005). One or more of these immunogens can be expressed in s-PIV-TBE. However, d-PIV-TBE may also be selected, because of its large insertion capacity. In addition to PIV-TBE, other PIV vaccines can be used as vectors, e.g., to protect from Lyme disease and another flavivirus disease, such as West Nile virus. Expression of these immunogens can be evaluated in cell culture, and immunogenicity/protection examined in available animal models (e.g., as described in Gipson et al., Vaccine 21:3875-3884, 2003; Labuda et al., Pathog. 2(e27):0251-0259, 2006). Immunogens of other pathogens can be similarly expressed, in addition to Lyme disease and tick immunogens, with the purpose of making multivalent vaccine candidates. Exemplary tick saliva immunogens that can be used in the invention include the following:
Additional details concerning the TBE-related PIVs and LAVs are provided in Example 2, below.
Other PIV and LAV-vectored vaccines against other non-flavivirus pathogens, including vaccines having dual action, eliciting protective immunity against both flavivirus (as specified by the vector envelope proteins) and non-flavivirus pathogens (as specified by expressed immunologic determinant(s)) can also be used. These are similar to the example of PIV-TBE-Lyme disease-tick vector vaccines described above. As mentioned above, such dual-action vaccines can be developed against a broad range of pathogens by expression of immunogens from, for example, viral, bacterial, fungal, and parasitic pathogens, and immunogens associated with cancer and allergy. As specific non-limiting examples, we describe herein the design and biological properties of PIV vectored-rabies and -respiratory syncytial virus (RSV) vaccine candidates constructed by expression of rabies virus G protein or RSV F protein in place of or in combination with various deletions in one- and two-component PIV vectors (see Example 3, below).
As is demonstrated in the Examples, below, s-PIV constructs may be advantageously used to stably deliver relatively short foreign immunogens (similar to Lyme disease agent OspA protein and tick saliva proteins), because insertions are combined with a relatively short AC deletion. Two-component PIV vectors may be advantageously used to stably express relatively large immunogens, such as rabies G protein and RSV F, as the insertions in such vectors are combined with, for example, large AprM-E, AC-prM-E, and/or ANS1 deletions. Some of the d-PIV components can be manufactured and used as vaccines individually, for instance, the PIV-RSV F construct described below containing a AC-prM-E deletion. In this case, the vaccine induces an immune response (e.g., neutralizing antibodies) predominantly against the expressed protein, but not against the flavivirus vector virus pathogen. In other examples of the invention, dual immunity is obtained by having immunity induced both to vector and insert components. Additionally, because of the large insertion capacity of PIV vectors, and the option of using two-component genomes, PIV vectors offer the opportunity to target several non-flavivirus pathogens simultaneously, e.g., by expressing foreign immunogens from two different non-flavivirus pathogens in the two components of a d-PIV.
In addition to the RSV F or G protein, rabies G protein, Lyme disease protective immunogens, and tick saliva proteins, as examples of foreign immunogens described above, other foreign immunogens can be expressed to target respective diseases including, for example, influenza virus type A and B immunogens. In these examples, a few short epitopes and/or whole genes of viral particle proteins can be used, such as the M2, HA, and NA genes of influenza A, and/or the NB or BM2 genes of influenza B. Shorter fragments of M2, NB, and BM2, corresponding for instance to M2e, the extracellular fragment of M2, can also be used. In addition, fragments of the HA gene, including epitopes identified as HA0 (23 amino acids in length, corresponding to the cleavage site in HA) can be used. Specific examples of influenza-related sequences that can be used in the invention include PAKLLKERGFFGAIAGFLE (HA0), PAKLLKERGFFGAIAGFLEGSGC(HA0), NNATFNYTNVNPISHIRGS (NBe), MSLLTEVETPIRNEWGCRCNDSSD (M2e), MSLLTEVETPTRNEWECRCSDSSD (M2e), MSLLTEVETLTRNGWGCRCSDSSD (M2e), EVETPTRN (M2e), SLLTEVETPIRNEWGCRCNDSSD (M2e), and SLLTEVETPIRNEWGCR (M2e). Additional M2e sequences that can be used in the invention include sequences from the extracellular domain of BM2 protein of influenza B (consensus MLEPFQ, e.g., LEPFQILSISGC), and the M2e peptide from the H5N1 avian flu (MSLLTEVETLTRNGWGCRCSDSSD).
Other examples of pathogen immunogens that can be delivered in the vectors of the invention include codon-optimized SIV or HIV gag (55 kDa), gp120, gp160, SIV mac239-rev/tat/nef genes or analogs from HIV, and other HIV immunogens; immunogens from HPV viruses, such as HPV16, HPV18, etc., e.g., the capsid protein L1 which self-assembles into HPV-like particles, the capsid protein L2 or its immunodominant portions (e.g., amino acids 1-200, 1-88, or 17-36), the E6 and E7 proteins which are involved in transforming and immortalizing mammalian cells fused together and appropriately mutated (fusion of the two genes creates a fusion protein, referred to as E6E7Rb−, that is about 10-fold less capable of transforming fibroblasts, and mutations of the E7 component at 2 residues renders the resulting fusion protein mutant incapable of inducing transformation (Boursnell et al., Vaccine 14:1485-1494, 1996). Other immunogens include protective immunogens from HCV, CMV, HSV2, viruses, malaria parasite, Mycobacterium tuberculosis causing tuberculosis, C. difficile, and other nosocomial infections, that are known in the art, as well as fungal pathogens, cancer immunogens, and proteins associated with allergy that can be used as vaccine targets.
Foreign immunogen inserts of the invention, such as RSV immunogens as described herein, can be modified in various ways. For instance, codon optimization is used to increase the level of expression and eliminate long repeats in nucleotide sequences to increase insert stability in the RNA genome of PIV vectors. Further, the genes can be truncated at N- and/or C-termini, or by internal deletion(s), or modified by specific amino acid changes to increase visibility to the immune system and immunogenicity. Immunogenicity can be increased by chimerization of proteins with immunostimulatory moieties well known in the art, such as TLR agonists, stimulatory cytokines, components of complement, heat-shock proteins, etc. (e.g., reviewed in “Immunopotentiators in Modern Vaccines,” Schijns and O'Hagan Eds., 2006, Elsevier Academic Press: Amsterdam, Boston).
With respect to construction of dual vaccines against rabies and other flavivirus diseases, other combinations, such as TBE+rabies, YF+rabies, etc., can be of interest both for human and veterinary use in corresponding geographical regions, and thus can be similarly generated. Possible designs of expression constructs are not limited to those described herein. For example deletions and insertions can be modified, genetic elements can be rearranged, or other genetic elements (e.g. non-flavivirus, non-rabies signals for secretion, intracellular transport determinants, inclusion of or fusion with immunostimulatory moieties such as cytokines, TLR agonists such as flagellin, multimerization components such as leucine zipper, and peptides that increase the period of protein circulation in the blood) can be used to facilitate antigen presentation and increase immunogenicity. Further, such designs can be applied to s-PIV and d-PIV vaccine candidates based on vector genomes of other flaviviruses, and expressing immunogens of other pathogens, e.g., including but not limited to pathogens described in elsewhere herein.
Other examples of PIV and LAV vectors of the invention including combination vaccines such as DEN+Chikungunya virus (CHIKV) and YF+CHIKV. CHIKV, an alphavirus, is endemic in Africa, South East Asia, Indian subcontinent and the Islands, and the Pacific Islands and shares ecological/geographical niches with YF and DEN1-4. It causes serious disease primarily associated with severe pain (arthritis, other symptoms similar to DEN) and long-lasting sequelae in the majority of patients (Simon et al., Med. Clin. North Am. 92:1323-1343, 2008; Seneviratne et al., J. Travel Med. 14:320-325, 2007). Other examples of PIV and LAV vectors of the invention include YF+Ebola or DEN+Ebola, which co-circulate in Africa.
Immunogens for the above-noted non-flavivirus pathogens, sequences of which are well known in the art, may include glycoprotein B or a pp 65/1E1 fusion protein of CMV (Reap et al., Vaccine 25(42):7441-7449, 2007; and references therein), several TB proteins (reviewed in Skeiky et al., Nat. Rev. Microbiol. 4(6):469-476, 2006), malaria parasite antigens such as RTS,S (a pre-erythrocytic circumsporozoite protein, CSP) and others (e.g., reviewed in Li et al., Vaccine 25(14):2567-2574, 2007), CHIKV envelope proteins E1 and E2 (or the C-E2-E1, E2-E1 cassettes), HCV structural proteins C-E1-E2 forming VLPs (Ezelle et al., J. Virol. 76(23):12325-12334, 2002) or other proteins to induce T=cell responses, Ebola virus glycoprotein GP (Yang et al., Virology 377(2):255-264, 2008).
In addition to the immunogens described above, the vectors described herein may include one or more immunogen(s) derived from or that direct an immune response against one or more viruses (e.g., viral target antigen(s)) including, for example, a dsDNA virus (e.g., adenovirus, herpesvirus, epstein-barr virus, herpes simplex type 1, herpes simplex type 2, human herpes virus simplex type 8, human cytomegalovirus, varicella-zoster virus, poxvirus); ssDNA virus (e.g., parvovirus, papillomavirus (e.g., E1, E2, E3, E4, E5, E6, E7, E8, BPV1, BPV2, BPV3, BPV4, BPV5, and BPV6 (In Papillomavirus and Human Cancer, edited by H. Pfister (CRC Press, Inc. 1990)); Lancaster et al., Cancer Metast. Rev. pp. 6653-6664, 1987; Pfister et al., Adv. Cancer Res. 48:113-147, 1987)); dsRNA viruses (e.g., reovirus); (+)ssRNA viruses (e.g., picornavirus, coxsackie virus, hepatitis A virus, poliovirus, togavirus, rubella virus, flavivirus, hepatitis C virus, yellow fever virus, dengue virus, west Nile virus); (−)ssRNA viruses (e.g., orthomyxovirus, influenza virus, rhabdovirus, paramyxovirus, measles virus, mumps virus, parainfluenza virus, rhabdovirus, rabies virus); ssRNA-RT viruses (e.g., retrovirus, human immunodeficiency virus (HIV)); and dsDNA-RT viruses (e.g. hepadnavirus, hepatitis B). Immunogens may also be derived from other viruses not listed above but available to those of skill in the art.
With respect to HIV, immunogens may be selected from any HIV isolate. As is well-known in the art, HIV isolates are now classified into discrete genetic subtypes. HIV-1 is known to comprise at least ten subtypes (A, B, C, D, E, F, G, H, J, and K). HIV-2 is known to include at least five subtypes (A, B, C, D, and E). Subtype B has been associated with the HIV epidemic in homosexual men and intravenous drug users worldwide. Most HIV-1 immunogens, laboratory adapted isolates, reagents and mapped epitopes belong to subtype B. In sub-Saharan Africa, India, and China, areas where the incidence of new HIV infections is high, HIV-1 subtype B accounts for only a small minority of infections, and subtype HIV-1 C appears to be the most common infecting subtype. Thus, in certain embodiments, it may be desirable to select immunogens from HIV-1 subtypes B and/or C. It may be desirable to include immunogens from multiple HIV subtypes (e.g., HIV-1 subtypes B and C, HIV-2 subtypes A and B, or a combination of and HIV-2 subtypes) in a single immunological composition. Suitable HIV immunogens include ENV, GAG, POL, NEF, as well as variants, derivatives, and fusion proteins thereof, for example.
Immunogens may also be derived from or direct an immune response against one or more bacterial species (spp.) (e.g., bacterial target antigen(s)) including, for example, Bacillus spp. (e.g., Bacillus anthracis), Bordetella spp. (e.g., Bordetella pertussis), Borrelia spp. (e.g., Borrelia burgdorferi), Brucella spp. (e.g., Brucella abortus, Brucella canis, Brucella melitensis, Brucella suis), Campylobacter spp. (e.g., Campylobacter jejuni), Chlamydia spp. (e.g., Chlamydia pneumoniae, Chlamydia psittaci, Chlamydia trachomatis), Clostridium spp. (e.g., Clostridium botulinum, Clostridium difficile, Clostridium perfringens, Clostridium tetani), Corynebacterium spp. (e.g., Corynebacterium diptheriae), Enterococcus spp. (e.g., Enterococcus faecalis, enterococcus faecum), Escherichia spp. (e.g., Escherichia coli), Francisella spp. (e.g., Francisella tularensis), Haemophilus spp. (e.g., Haemophilus influenza), Helicobacter spp. (e.g., Helicobacter pylori), Legionella spp. (e.g., Legionella pneumophila), Leptospira spp. (e.g., Leptospira interrogans), Listeria spp. (e.g., Listeria monocytogenes), Mycobacterium spp. (e.g., Mycobacterium leprae, Mycobacterium tuberculosis), Mycoplasma spp. (e.g., Mycoplasma pneumoniae), Neisseria spp. (e.g., Neisseria gonorrhea, Neisseria meningitidis), Pseudomonas spp. (e.g., Pseudomonas aeruginosa), Rickettsia spp. (e.g., Rickettsia rickettsii), Salmonella spp. (e.g., Salmonella typhi, Salmonella typhinurium), Shigella spp. (e.g., Shigella sonnei), Staphylococcus spp. (e.g., Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, coagulase negative staphylococcus (e.g., U.S. Pat. No. 7,473,762)), Streptococcus spp. (e.g., Streptococcus agalactiae, Streptococcus pneumoniae, Streptococcus pyrogenes), Treponema spp. (e.g., Treponema pallidum), Vibrio spp. (e.g., Vibrio cholerae), and Yersinia spp. (Yersinia pestis). Immunogens may also be derived from or direct the immune response against other bacterial species not listed above but available to those of skill in the art.
Immunogens may also be derived from or direct an immune response against one or more parasitic organisms (spp.) (e.g., parasite target antigen(s)) including, for example, Ancylostoma spp. (e.g., A. duodenale), Anisakis spp., Ascaris lumbricoides, Balantidium coli, Cestoda spp., Cimicidae spp., Clonorchis sinensis, Dicrocoelium dendriticum, Dicrocoelium hospes, Diphyllobothrium latum, Dracunculus spp., Echinococcus spp. (e.g., E. granulosus, E. multilocularis), Entamoeba histolytica, Enterobius vermicularis, Fasciola spp. (e.g., F. hepatica, F. magna, F. gigantica, F. jacksoni), Fasciolopsis buski, Giardia spp. (Giardia lamblia), Gnathostoma spp., Hymenolepis spp. (e.g., H. nana, H. diminuta), Leishmania spp., Loa boa, Metorchis spp. (M. conjunctus, M. albidus), Necator americanus, Oestroidea spp. (e.g., botfly), Onchocercidae spp., Opisthorchis spp. (e.g., O. viverrini, O. felineus, O. guayaquilensis, and O. noverca), Plasmodium spp. (e.g., P. falciparum), Protofasciola robusta, Parafasciolopsis fasciomorphae, Paragonimus westermani, Schistosoma spp. (e.g., S. mansoni, S. japonicum, S. mekongi, S. haematobium), Spirometra erinaceieuropaei, Strongyloides stercoralis, Taenia spp. (e.g., T. saginata, T. solium), Toxocara spp. (e.g., T. canis, T. cati), Toxoplasma spp. (e.g., T. gondii), Trichobilharzia regenti, Trichinella spiralis, Trichuris trichiura, Trombiculidae spp., Trypanosoma spp., Tunga penetrans, and/or Wuchereria bancrofti. Immunogens may also be derived from or direct the immune response against other parasitic organisms not listed above but available to those of skill in the art.
Immunogens may be derived from or direct the immune response against tumor target antigens (e.g., tumor target antigens). The term tumor target antigen (TA) may include both tumor-associated antigens (TAAs) and tumor-specific antigens (TSAs), where a cancerous cell is the source of the antigen. A TA may be an antigen that is expressed on the surface of a tumor cell in higher amounts than is observed on normal cells or an antigen that is expressed on normal cells during fetal development. A TSA is typically an antigen that is unique to tumor cells and is not expressed on normal cells. TAs are typically classified into five categories according to their expression pattern, function, or genetic origin: cancer-testis (CT) antigens (i.e., MAGE, NY-ESO-1); melanocyte differentiation antigens (e.g., Melan A/MART-1, tyrosinase, gp100); mutational antigens (e.g., MUM-1, p53, CDK-4); overexpressed ‘self’ antigens (e.g., HER-2/neu, p53); and viral antigens (e.g., HPV, EBV). Suitable TAs include, for example, gp100 (Cox et al., Science 264:716-719, 1994), MART-1/Melan A (Kawakami et al., J. Exp. Med., 180:347-352, 1994), gp75 (TRP-1) (Wang et al., J. Exp. Med., 186:1131-1140, 1996), tyrosinase (Wolfel et al., Eur. J. Immunol., 24:759-764, 1994), NY-ESO-1 (WO 98/14464; WO 99/18206), melanoma proteoglycan (Hellstrom et al., J. Immunol., 130:1467-1472, 1983), MAGE family antigens (e.gl, MAGE-1, 2, 3, 4, 6, and 12; Van der Bruggen et al., Science 254:1643-1647, 1991; U.S. Pat. No. 6,235,525), BAGE family antigens (Boel et al., Immunity 2:167-175, 1995), GAGE family antigens (e.g., GAGE-1,2; Van den Eynde et al., J. Exp. Med. 182:689-698, 1995; U.S. Pat. No. 6,013,765), RAGE family antigens (e.g., RAGE-1; Gaugler et al., Immunogenetics 44:323-330, 1996; U.S. Pat. No. 5,939,526), N-acetylglucosaminyltransferase-V (Guilloux et al., J. Exp. Med. 183:1173-1183, 1996), p15 (Robbins et al., J. Immunol. 154:5944-5950, 1995), β-catenin (Robbins et al., J. Exp. Med., 183:1185-1192, 1996), MUM-1 (Coulie et al., Proc. Natl. Acad. Sci. U.S.A. 92:7976-7980, 1995), cyclin dependent kinase-4 (CDK4) (Wolfel et al., Science 269:1281-1284, 1995), p21-ras (Fossum et al., Int. J. Cancer 56:40-45, 1994), BCR-abd (Bocchia et al., Blood 85:2680-2684, 1995), p53 (Theobald et al., Proc. Natl. Acad. Sci. U.S.A. 92:11993-11997, 1995), p185 HER2/neu (erb-B1; Fisk et al., J. Exp. Med., 181:2109-2117, 1995), epidermal growth factor receptor (EGFR) (Harris et al., Breast Cancer Res. Treat, 29:1-2, 1994), carcinoembryonic antigens (CEA) (Kwong et al., J. Natl. Cancer Inst., 85:982-990, 1995) U.S. Pat. Nos. 5,756,103; 5,274,087; 5,571,710; 6,071,716; 5,698,530; 6,045,802; EP 263933; EP 346710; and EP 784483; carcinoma-associated mutated mucins (e.g., MUC-1 gene products; Jerome et al., J. Immunol., 151:1654-1662, 1993); EBNA gene products of EBV (e.g., EBNA-1; Rickinson et al., Cancer Surveys 13:53-80, 1992); E7, E6 proteins of human papillomavirus (Ressing et al., J. Immunol. 154:5934-5943, 1995); prostate specific antigen (PSA; Xue et al., The Prostate 30:73-78, 1997); prostate specific membrane antigen (PSMA; Israeli et al., Cancer Res. 54:1807-1811, 1994); idiotypic epitopes or antigens, for example, immunoglobulin idiotypes or T cell receptor idiotypes (Chen et al., J. Immunol. 153:4775-4787, 1994); KSA (U.S. Pat. No. 5,348,887), kinesin 2 (Dietz, et al., Biochem. Biophys. Res. Commun. 275(3):731-738, 2000), HIP-55, TGFβ-1 anti-apoptotic factor (Toomey et al., Br. J. Biomed. Sci. 58(3):177-183, 2001), tumor protein D52 (Bryne et al., Genomics 35:523-532, 1996), H1FT, NY-BR-1 (WO 01/47959), NY-BR-62, NY-BR-75, NY-BR-85, NY-BR-87, and NY-BR-96 (Scanlan, M. Serologic and Bioinformatic Approaches to the Identification of Human Tumor Antigens, in Cancer Vaccines 2000, Cancer Research Institute, New York, N.Y.), and/or pancreatic cancer antigens (e.g., SEQ ID NOs: 1-288 of U.S. Pat. No. 7,473,531). Immunogens may also be derived from or direct the immune response against include TAs not listed above but available to one of skill in the art.
In addition to the specific immunogen sequences listed above, the invention also includes the use of analogs of the sequences. Such analogs include sequences that are, for example, at least 80%, 90%, 95%, or 99% identical to the reference sequences, or fragments thereof. The analogs can include one or more substitutions or deletions, e.g., substitutions of conservative amino acids as described herein. The analogs also include fragments of the reference sequences that include, for example, one or more immunogenic epitopes of the sequences. Further, the analogs include truncations or expansions of the sequences (e.g., insertion of additionaUrepeat immunodominant/helper epitopes) by, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11-20, etc., amino acids on either or both ends. Truncation may remove immunologically unimportant or interfering sequences, e.g., within known structural/immunologic domains, or between domains; or whole undesired domains can be deleted; such modifications can be in the ranges 21-30, 31-50, 51-100, 101-400, etc. amino acids. The ranges also include, e.g., 20-400, 30-100, and 50-100 amino acids.
The invention also includes compositions including mixtures of two or more PIVs and/or PIV vectors, as described herein. As discussed above, use of such mixtures or cocktails may be particularly advantageous when induction of immunity to more than one immunogen and/or pathogen is desired. This may be useful, for example, in vaccination against different flaviviruses that may be endemic to the region in which the vaccine recipient resides. This may also be useful in the context of administration of multiple immunogens against the same target.
Non-limiting examples of PIV cocktails included in the invention are those including PIV-JE+PIV-DEN, and PIV-YF+PIV-DEN. In both of these examples, the PIVs for either or both components can be single or dual component PIVs, as described above. In addition, in the case of the Ply-DEN, the PIV can include sequences of just one dengue serotype selected from the group consisting of dengue serotypes 1-4, or the cocktail can include PIVs expressing sequences from two, three, or all four of the serotypes. Further, the TBE/Borrelia burgdorferi/tick saliva protein (e.g., 64TRP, Isac, Salp20) vaccines described herein can be based on including the different immunogens within a single PIV or live attenuated flavivirus, or can be based on mixtures of PIVs (or LAVs), which each include one or more of the immunogens. The cocktails of the invention can be formulated as such or can be mixed just prior to administration.
The invention includes the PIV and LAV vectors, as well as corresponding nucleic acid molecules, pharmaceutical or vaccine compositions, and methods of their use and preparation. The PIV and LAV vectors of the invention can be used, for example, in vaccination methods to induce an immune response to RSV and/or the flavivirus vector, and/or another expressed immunogen, as described herein. These methods can be prophylactic, in which case they are carried out on subjects (e.g., human subjects or other mammalian subjects) not having, but at risk of developing infection or disease caused by RSV or flavivirus and/or a pathogen from which another expressed immunogen is derived. Such methods include instances in which a subject becomes infected by RSV, but is able to ward off the infection and significant symptomatic disease, because of the treatment according to the invention. The methods can also be therapeutic, in which they are carried out on subjects already having an infection by one or more of the relevant pathogens, such as RSV. Such methods include the amelioration of one or more symptoms of the infection, whether partial or complete. Further, the viruses and vectors can be used individually or in combination with one another or other vaccines. The subjects treated according to the methods of the invention include humans, as well as non-human mammals (e.g., livestock, such as, cattle, pigs, horses, sheep, and goats, and domestic animals, including dogs and cats). Of particular interest with respect to vaccination against RSV are infants and young children, including pre-mature infants, as well as middle aged and elderly people. Thus, for example, human patients age 1 day to five years (e.g., 2 months to 3 years, or 4 months to two years), or age 50 to 65 and above.
Formulation of the PIV and LAV vectors of the invention can be carried out using methods that are standard in the art. Numerous pharmaceutically acceptable solutions for use in vaccine preparation are well known and can readily be adapted for use in the present invention by those of skill in this art (see, e.g., Remington's Pharmaceutical Sciences (18th edition), ed. A. Gennaro, 1990, Mack Publishing Co., Easton, Pa.). In two specific examples, the PIV vectors, PIVs, LAV vectors, and LAVs are formulated in Minimum Essential Medium Earle's Salt (MEME) containing 7.5% lactose and 2.5% human serum albumin or MEME containing 10% sorbitol. However, the PIV and LAV vectors can simply be diluted in a physiologically acceptable solution, such as sterile saline or sterile buffered saline.
The PIV and LAV vectors of the invention can be administered using methods that are well known in the art, and appropriate amounts of the viruses and vectors to be administered can readily be determined by those of skill in the art. What is determined to be an appropriate amount of virus to administer can be determined by consideration of factors such as, e.g., the size and general health of the subject to whom the virus is to be administered. For example, in the case of live, attenuated viruses of the invention, the viruses can be formulated as sterile aqueous solutions containing between 102 and 108, e.g., 103 to 107, infectious units (e.g., plaque-forming units or tissue culture infectious doses) in a dose volume of 0.1 to 1.0 ml. PIVs can be administered at similar doses and in similar volumes; PIV titers however are usually measured in, e.g., focus-forming units determined by immunostaining of foci, as these defective constructs tend not to form virus-like plaques. Doses can range between 102 and 108 FFU and administered in volumes of 0.1 to 1.0 ml.
All viruses and vectors of the invention can be administered by, for example, intradermal, subcutaneous, intramuscular, intraperitoneal, intranasal (e.g., by inhalation or nose drops), intravenous, or oral routes. In specific examples, dendritic cells are targeted by intradermal or transcutaneous administration, by use of, for example, microneedles or microabrasion devices. Further, the vaccines of the invention can be administered in a single dose or, optionally, administration can involve the use of a priming dose followed by a booster dose that is administered, e.g., 2-6 months later, as determined to be appropriate by those of skill in the art. Optionally, PIV vaccines can be administered via DNA or RNA immunization using methods known to those skilled in the art (Chang et al., Nat. Biotechnol. 26:571-577, 2008; Kofler et al., Proc. Natl. Acad. Sci. U.S.A. 101:1951-1956, 2004).
Optionally, adjuvants that are known to those skilled in the art can be used in the administration of the viruses and vectors of the invention. Adjuvants that can be used to enhance the immunogenicity of the viruses include, for example, liposomal formulations, synthetic adjuvants, such as (e.g., QS21), muramyl dipeptide, monophosphoryl lipid A, polyphosphazine, CpG oligonucleotides, or other molecules that appear to work by activating Toll-like Receptor (TLR) molecules on the surface of cells or on nuclear membranes within cells. Although these adjuvants are typically used to enhance immune responses to inactivated vaccines, they can also be used with live or replication-defective vaccines. Both agonists of TLRs or antagonists may be useful in the case of live or replication-defective vaccines. The vaccine candidates can be designed to express TLR agonists. In the case of a virus delivered via a mucosal route, for example, orally, mucosal adjuvants such as the heat-labile toxin of E. coli (LT) or mutant derivations of LT can be used as adjuvants. In addition, genes encoding cytokines that have adjuvant activities can be inserted into the vaccine candidates. Thus, genes encoding desired cytokines, such as GM-CSF, IL-2, IL-12, IL-13, IL-5, etc., can be inserted together with foreign immunogen genes to produce a vaccine that results in enhanced immune responses, or to modulate immunity directed more specifically towards cellular, humoral, or mucosal responses (e.g., reviewed in “Immunopotentiators in Modem Vaccines”, Schijns and O'Hagan Eds., 2006, Elsevier Academic Press: Amsterdam, Boston, etc.). Optionally, a patch containing a layer of an appropriate toxin-derived adjuvant, can be applied over the injection site. Toxin promotes local inflammation attracting lymphocytes, which leads to a more robust immune response.
Additional details concerning the invention are provided in the Examples, below. In the Examples, experiments are described in which PIVs based on WN, JE, and YF viruses (see, e.g., WO 2007/098267 and WO 2008/137163) were tested. Firstly, we demonstrated that the constructs are significantly more attenuated in a sensitive suckling mouse neurovirulence model (zero mortality at all tested doses) as compared to available LAV controls (YF 17D, YF/JE LAV, and YF/WN LAV). We demonstrated for the first time that d-PIV constructs were avirulent in this model and thus that two-component PIVs do not undergo uncontrolled (unlimited) spread in vivo and cannot cause clinical signs. Secondly, we performed comparisons of the immunogenicity and efficacy of the PIVs and the LAVs, and demonstrated that PIV vaccines can induce immune response comparable to LAVs and be equally efficacious (e.g., as observed for PIV-WN and YF/WN LAV pair of vaccines). In one pair examined, YF 17D LAV was significantly more immunogenic than PIV-YF. Thus, production of VLPs can vary between different, similarly designed PIV constructs. Specifically, we propose that PIV-YF does not generate a large amount of YF VLPs compared to PIV-WN (WN VLPs), and that increased production of VLPs can be achieved by genetic modifications at the C/prM junction in suboptimal PIV constructs. Specifically, the C/prM junction is an important location in the flavivirus polyprotein orchestrating the formation of viral envelope and synthesis of viral proteins (Yamshchikov and Compans, Virology 192:38-51, 1993; Amberg and Rice, J. Virol. 73:8083-8094, 1999; Stocks and Lobigs, J. Virol. 72:2141-2149, 1998). We propose that secretion of VLPs in PIV infected cells (in contrast to production of viral particles in whole viruses) can be increased by uncoupling of the viral protease and signalase cleavages at the junction, or use of a strong heterologous signal peptide (tPA, etc.) in place of the signal for prM, or by mutagenesis of the signal for prM. The efficiency of signalase cleavage at the C/prM junction of flaviviruses is low (Stocks and Lobigs, J. Virol. 72:2141-2149, 1998), e.g., as predicted by SignalP 3.0 on-line program. It is expected that more efficient cleavage efficiency can be achieved by analysis of specific amino acid substitutions near the cleavage site with SignalP 3.0 (e.g., as described in application WO 2008/100464), followed by incorporation of chosen mutation(s) into PIV genomes, recovery of PIV progeny and measuring VLP secretion. Non-flavivirus signals are inserted by methods standard in the art. Uncoupling between the viral protease and signalase cleavages can be achieved by ablating the viral cleavage site by any non-conservative mutation (e.g., RRS in YF17D C to RRA or GRS or RSS, etc.), or deletion of the entire site or some of its 3 residues. If necessary, formation of free N-terminus of the signal of foreign protein can be achieved by using such elements as autoprotease, or termination codon followed by an IRES. Alternatively, the native AUG initiation codon of C can be ablated (in constructs where C protein sequence is unnecessary, e.g., AC PIV) and AUG placed in front of foreign gene. Optimization of vector signal can be performed by random mutagenesis, e.g., by insertion of synthetic randomized sequence followed by identification of viable PIV variants with increased VLP secretion.
We also discovered that PIV constructs were substantially more immunogenic in hamsters when administered by the IP route, as compared to the subcutaneous route. We concluded that this was most likely due to better targeting of antigen presenting cells in lymphoid tissues, which are abundant in the abdomen, but not abundant in tissues underlying the skin. Based on these observations, we concluded that efficient targeting of PIVs to dendritic cells, abundant in the skin, can be achieved by cutaneous inoculation, e.g., via skin microabrasion or intradermal injection using microneedles (Dean et al., Hum Vaccin. 1:106-111, 2005).
Further, we have carried out experiments to show the feasibility of administering mixtures, or cocktails, of different PIVs, such as those described herein (e.g., JE+DEN and YF+DEN). In order to administer cocktails, it is important to verify that there is no interference between co-administered components, and that a balanced immune response is induced. Several PIV mixtures were used to immunize rodents and immune responses were compared to PIV constructs administered individually. No interference was observed in mixtures, and thus cocktail PIV vaccines are feasible. Such formulations may be of particular significance in geographical regions where different flaviviruses co-circulate. This could be also used to simultaneously administer several PIV-based vaccines against non-flavivirus pathogens.
Further, we have demonstrated that no neutralizing antibody response is induced against packaging envelope after at least two doses of PIV (and thus antibodies are elicited against VLPs secreted from infected cells). This was demonstrated using the helper (AprM-E) component of a d-PIV (see in
These and other aspects of the invention are further described in the Examples, below.
Materials used in the studies described below are described in Table 1 and the references cited therein. These include s-PIV-WN (based on wt WN virus strain NY99 sequences), s-PIV-JE, s-PIV-WN/JE (based on wt WN virus backbone and prM-E genes from wt JE virus Nakayama strain), s-PIV-YF/WN(YF 17D backbone and prM-E genes from WN virus), and s-PIV-YF (based on YF 17D sequences). Additional materials include d-PIV-YF (YF d-PIV, grown in regular BHK cells (Shustov et al., J. Virol. 21:11737-11748, 2007), and two-component d-PIV-WN (grown in regular Vero cells; Suzuki et al., J. Virol. 82:6942-6951, 2008).
Attenuation of these PIV prototypes was compared to LAVs YF 17D, a chimeric YF/JE virus, and a chimeric YF/WN virus in suckling mouse NV test (IC inoculation) using highly susceptible 5-day old ICR mice (the chimeric viruses include yellow fever capsid and non-structural sequences, and JE or WN prM-E sequences). None of the animals that received PIV constructs showed clinical signs or died, while mortality was observed in animals inoculated with LAVs (Table 2). The YF 17D virus is neurovirulent for mice of all ages, while the chimeric vaccines are not neurovirulent for adult mice, but can cause dose-dependent mortality in more sensitive suckling mice (Guirakhoo et al., Virology 257:363-372, 1999; Arroyo et al., J. Virol. 78:12497-12507, 2004). Accordingly, 90%-100% of suckling mice that received doses as low as 1 PFU of YF 17D died. YF/JE and YF/WN LAVs caused partial mortality at much higher doses (>2 log10 PFU and 3 log10 PFU, respectively), with longer average survival time (AST) of animals that died, as expected. Thus, PIV constructs are completely avirulent in this sensitive model (at least 20,000-200,000 times less neurovirulent than the licensed YF 17D vaccine).
The YF d-PIV and WN d-PIV caused no mortality or clinical signs. Thus, the two-component PIV variants that theoretically could spread within brain tissue from cells co-infected by both of their components did not cause disease. Moreover, we tried to detect the d-PIVs in the brains of additional animals in this experiment, sacrificed on day 6 post-inoculation by titration, and detected none (brain tissues from 10 and 11 mice that received 4 logjo FFU of YF d-PIV and WN d-PIV, respectively, were homogenized and used for titration). Thus, the d-PIVs did not cause spreading infection characteristic of whole virus. YF/JE LAV has been shown to replicate in the brain of adult ICR mice inoculated by the IC route with a peak titer of 6 log10 PFU/g on day 6, albeit without clinical signs (Guirakhoo et al., Virology 257:363-372, 1999). Co-infection of cells with components of a d-PIV is clearly a less efficient process than infection with whole virus. The data show that d-PIV replication in vivo is quickly brought under control by innate immune responses (and adaptive responses in older animals).
Immunogenicity/efficacy of the PIV prototypes described above was compared to that of chimeric LAV counterparts and YF 17D in mice and Syrian hamsters. The general experiment design is illustrated in
The YF 17D control virus was highly immunogenic (e.g., PRNT50 titer 1:1,280 on day 34), and thus it is able to infect cells and replicate efficiently in vivo, and its envelope is a strong immunogen. Therefore, it is unlikely that low immunogenicity of PIV-YE was due to its inability to infect cells or replicate efficiently in infected cells in vivo. We believe that the low immunogenicity of PIV-YF (e.g., compared to PIV-WN) was most likely due to a low-level production of YF-specific VLPs in PIV-YF infected cells (while VLP secretion is high in PIV-WN infected cells). As discussed above, we propose that immunogenicity of PIV-YF can be significantly increased, e.g., by appropriate modifications at the C/prM junction, e.g., by uncoupling the two protease cleavages that occur at this junction (viral protease and signalase cleavages), and/or by using a strong heterologous signal [e.g., rabies virus G protein signal, or eukaryotic tissue plasminogen activator (tPA) signal (Malin et al., Microbes and Infection, 2:1677-1685, 2000), etc.] in place of the YF signal for prM.
A similar experiment was performed in ˜4.5-week old Syrian hamsters, to compare immunogenicity of PIV constructs to LAV controls in this model. Animals were immunized SC with graded doses of the test articles (Table 4). PIV-WN was highly immunogenic, e.g., WN-specific PRNT50 titers on day 38 (pre-challenge) were 1:320, 1:640, and 1:1280 in groups that received 5, 6, and 6 (prime)+5 (boost) log10 FFU doses, respectively. This was somewhat lower compared to YF/WN LAV 4 log10 PFU control (≧1:2560). PIV-JE and -YF induced detectable specific neutralizing antibody responses, albeit with lower titers compared to YF/JE LAV and YF 17D controls. All animals immunized with PIV-WN and YF/WN were solidly protected from lethal challenge with wt WN virus as evidenced by the absence of mortality and morbidity (e.g., loss of body weight after challenge), as well as absence or a significant reduction of postchallenge WN virus viremia. Mock-immunized animals were not protected (Table 4). PIV-JE and -WN protected animals from respective challenge in dose-dependent fashion. Protective efficacy in this experiment is additionally illustrated in
In another hamster experiment, animals were immunized with PIV constructs by the IP route, with two doses. Table 5 compares neutralizing immune responses (specific for each vaccine) determined in pooled sera of hamsters in the above-described experiment (SC inoculation) to those after IP immunization, for PIV-WN, -YF/WN, -WN/JE, and -YF after the first dose (days 20-21) and second dose (days 34-38). A clear effect of the immunization route was observed both after the 1st and 2nd doses. For instance, for PIV-WN after 1st dose, SC immunization resulted in WN-specific PRNT50 titer of 1:40, while IP inoculation resulted in much higher titer 1:320 (and after the 2nd dose, titers were similar). A more pronounced effect was observed for other constructs after both the 1st and 2nd doses. Interestingly, PIV-YF/WN was very highly immunogenic by IP route (titer 1:320 after 1st IP dose vs. 1:20 by SC, and 1:1,280 after 2nd dose vs. 1:160 by SC). Similarly, immunogenicity of PIV-JE was significantly increased (e.g., JE-specific titer of 1:640 after two IP poses). Thus, better targeting of lymphoid cells, specifically antigen-presenting cells (which are more abundant in the abdomen as opposed to tissues under the skin), is an important consideration for use of PIV vaccines. In humans, efficient targeting of dendritic cells of the skin, increasing the magnitude of immune response, can be achieved by intradermal delivery, which we thus propose for a route for PIV immunization of humans.
In the above-described experiments, we also determined whether a neutralizing antibody response was induced against packaging envelopes (as opposed to response to VLPs encoded by PIV constructs and secreted by infected cells). No WN-specific neutralizing antibodies were detected by PRNT50 in animals immunized with 5 log10FFU of the second component of WN d-PIV, containing the ΔC-prM-E deletion and thus not encoding VLPs, but packaged into the WN envelope in BHK-CprME(WN) helper cells, and no YF-specific neutralizing activity was found in sera from animals immunized with 4 log10 FFU of the second component of YF d-PIV packaged in YF envelope. No YF-specific neutralizing response was induced by two doses of PIV-YF/WN packaged into YF envelope, and similarly, no WN-specific response was induced by two doses of PIV-JE packaged into WN envelope. The absence of neutralizing response against packaging envelopes permits manufacturing different PIV vaccines in one (universal) manufacturing helper cell line, or immunization of one individual with different recombinant vaccines based on the same vector, according to the present invention.
Because PIVs undergo a single (optionally several, but limited) round(s) of replication in vivo, we considered that mixtures of different PIV vaccines can be administered without interference between individual constructs in the mixture (cocktail). To elucidate whether PIV vaccines can be used in cocktail formulations, immune responses in mice and hamsters to several PIV constructs given as mixtures were compared to the same constructs given individually. Similar results were obtained in both animal models. Results of mouse experiments are shown in Table 6. Similar anti-JE neutralizing antibody titers were observed in pools of sera from animals that were given one or two doses of either PIV-JE+PIV-WN mixture or PIV-JE alone (1:20 vs. 1:80 and 1:640 vs. 1:160, for one and two doses, respectively). Similarly, WN-specific titers against PIV-JE+PIV-WN mixture and PIV-WN alone were similar (1:320 vs. 1:640 and 1:5,120 vs. 1:5,120 for one and 2 doses, respectively). No or little cross-specific response was induced by either PIV-JE or -WN. The result was also confirmed by measuring PRNT50 titers in sera from individual animals. Thus, it is clear that PIV vaccines can be efficiently administered as cocktails, inducing immunity against two or more flavivirus pathogens. In addition, as discussed above, various cocktails can be made between non-flavivirus PIV vaccines, or between any of flavivirus and non-flavivirus PIV vaccines.
Different PIV prototypes were serially passaged up to 10 times in helper BHK cells, for s-PIVs, or in regular Vero cells, for d-PIVs. Samples harvested after each passage were titrated in Vero cells by immunostaining. Constructs grew to high titers, and no recombination restoring whole virus was observed. For instance, PIV-WN consistently grew to titers 7-8 log10 FFU/ml in BHK-CprME(WN) helper cells (containing a VEE replicon expressing the WN virus C-prM-E proteins), and WN d-PIV grew to titers exceeding 8 log10 FFU/ml in Vero cells, without recombination.
PIV-TBE vaccine candidates can be assembled based entirely on sequences from wt TBE virus or the closely serologically related Langat (LGT) virus (naturally attenuated virus, e.g., wt strain TP-21 or its empirically attenuated variant, strain E5), or based on chimeric sequences containing the backbone (capsid and non-structural sequences) from YF 17D or other flaviviruses, such as WN virus, and the prM-E envelope protein genes from TBE, LGT, or other serologically related flaviviruses from the TBE serocomplex. YF/TBE LAV candidates are constructed based on the backbone from YF 17D and the prM-E genes from TBE or related viruses (e.g., the E5 strain of LGT), similar to other chimeric LAV vaccines.
Construction of PIV-TBE and YF/TBE LAV vaccine prototypes was performed by cloning of appropriate genetic elements into plasmids for PIV-WN (Mason et al., Virology 351:432-443, 2006; Suzuki et al., J. Virol. 82:6942-6951, 2008), or plasmids for chimeric LAVs (e.g., pBSA-AR1, a single-plasmid version of infectious clone of YF/JE LAV; WO 2008/036146), respectively, using standard methods in the art of reverse genetics. The prM-E sequences of TBE virus strain Hypr (GenBank accession number U39292) and LGT strain E5 (GenBank accession number AF253420) were first computer codon-optimized to conform to the preferential codon usage in the human genome, and to eliminate nucleotide sequence repeats longer than 8 nt to ensure high genetic stability of inserts (if determined to be necessary, further shortening of nt sequence repeats can be performed). The genes were chemically synthesized and cloned into plasmids for PIV-WN and YF/JE LAV, in place of corresponding prM-E genes. Resulting plasmids were in vitro transcribed and appropriate cells (Vero for chimeric viruses, and helper BHK cells for PIV) were transfected with RNA transcripts to generate virus/PIV samples.
In YF/TBE constructs containing either the TBE Hypr (plasmids p42, p45, and p59) or LGT E5 (plasmid P43) prM-E genes, two different types of the C/prM junction were first examined (see in
PIV-WN/TBE variants were constructed, and packaged PIV samples were derived from plasmids p39 and p40 (
Other PIV-TBE variants based entirely on wt TBE (Hypr strain) and LGT virus (TP21 wild type strain or attenuated E5 strain), and chimeric YF 17D backbone/prM-E (TBE or LGT) sequences are also included in the invention. Helper cells providing appropriate C, C-prM-E, etc., proteins (e.g., TBE-specific) for trans-complementation can be constructed by means of stable DNA transfection or through the use of an appropriate vector, e.g., an alphavirus replicon, such as based on VEE strain TC-83, with antibiotic selection of replicon-containing cells. Vero and BHK21 cells can be used in practice of the invention. The former are an approved substrate for human vaccine manufacture; any other cell line acceptable for human and/or veterinary vaccine manufacturing can be also used. In addition to s-PIV constructs, d-PIV constructs can also be assembled. To additionally ascertain safety for vaccinees and the environment, appropriate modifications can be employed, including the use of degenerate codons and complementary mutations in the 5′ and 3′ CS elements, to minimize chances of recombination that theoretically could result in viable virus. Following construction, all vaccine candidates can be evaluated in vitro for manufacturability/stability, and in vivo for attenuation and immunogenicity/efficacy, in available pre-clinical animal models, such as those used in development and quality control of TBE and YF vaccines.
Young adult ICR mice (˜3.5 week-old), were inoculated with graded doses of PIV-TBE and YF/TBE LAV candidates by the IC route to measure neurovirulence, or IP route to measure neuroinvasiveness (and later immunogenicity/efficacy). Animals that received 5 log10 FFU of PIV-Hypr (p39 and p40) variants by both routes survived and showed no signs of sickness, similar to mock-inoculated animals (Table 7), and thus PIV-TBE vaccines are completely avirulent. Mice inoculated IC with YF 17D control (1-3 log10 PFU) showed dose-dependent mortality, while all animals inoculated IP (5 log10 PFU) survived, in accord with the knowledge that YF 17D virus is not neuroinvasive. All animals that received graded IC doses (2-4 log10 PFU) of YF/TBE LAV prototypes p42, p45, p43, and p59 died (moribund animals were humanely euthanized). These variants appear to be less attenuated than YF 17D, e.g., as evidenced by complete mortality and shorter AST at the 2 log10 PFU dose, the lowest dose tested for YF/TBE LAV candidates. The non-neurovirulent phenotype of PIV-TBE, virulent phenotype of YF/TBE LAV and intermediate-virulence phenotype of YF 17D are also illustrated in
TBE-specific neutralizing antibody responses in mice immunized IP with one or two doses of the PIV-TBE or YF/TBE LAV variants described above, or a human formalin-inactivated TBE vaccine control (1:30 of human dose) are being measured. Animals have been challenged with a high IP dose (500 PFU) of wt Hypr TBE virus; morbidity (e.g., weight loss), and mortality after challenge are monitored.
TBE-specific neutralizing antibody responses in mice immunized IP with one or two doses of the PIV-TBE or YF/TBE LAV variants described above (from experiment in Table 7), or a human formalin-inactivated TBE vaccine control (1:20 of human dose; one or two doses), or YF 17D and mock controls, were measured on day 20 by PRNT50 against wt TBE Hypr virus (Table 8; second dose of indicated test articles was given on day 14). [Titers were determined in individual sera, or pooled sera from two animals in most cases, or pooled sera from 4 animals for the YF 17D and Mock negative controls]. Titers in individual test samples as well as GMTs for each group are provided in Table 8. Titers in test samples were similar within each group, e.g., in groups immunized with PIVs, indicating high uniformity of immune response in animals. As expected, no TBE-specific neutralizing antibodies were detected in negative control groups (YF 17D and Mock; GMTs <1:10); accordingly, animals in these groups were not protected from challenge on day 21 post-immunization with a high IP dose (500 PFU) of wt Hypr TBE virus. Mortalities from partial observation (on day 9 post-challenge; observation being continued) are provided in Table 8, and dynamics of average post-challenge body weights indicative of morbidity are shown in
In the examples of recombinant PIV constructs described below, genes of interest were codon optimized (e.g., for efficient expression in a target vaccination host) and to eliminate long nt sequence repeats to increase insert stability (≧8 nt long; additional shortening of repeats can be performed if necessary), and then chemically synthesized. The genes were cloned into PIV-WN vector plasmids using standard methods of molecular biology well known in the art, and packaged PIVs were recovered following in vitro transcription and transfection of appropriate helper (for s-PIVs) or regular (for d-PIVs) cells.
Expression of Rabies Virus G Protein in WN s-PIV and d-PIV
Rabies virus, Rhabdoviridae family, is a significant human and veterinary pathogen. Despite the availability of several (killed) vaccines, improved vaccines are still needed for both veterinary and human use (e.g. as an inexpensive pre-exposure prophylactic vaccines). Rabies virus glycoprotein G mediates entry of the virus into cells and is the main immunogen. It has been expressed in other vectors with the purpose of developing veterinary vaccines (e.g., Pastoret and Brochier, Epidemio. Infect. 116:235-240, 1996; Li et al., Virology 356:147-154, 2006).
Full length rabies virus G protein (original Pasteur virus isolate, GenBank accession number NC—001542) was codon-optimized, chemically synthesized, and inserted adjacent to the ΔC, ΔprM-E and ΔC-prM-E deletions in PIV-WN vectors (
Packaged WN(ΔC)-rabiesG, WN(ΔprME)-rabiesG, and WN(ΔCprME)-rabiesG PIVs were produced by transfection of helper BHK cells complementing the PIV vector deletion [containing a Venezuelan equine encephalitis virus (strain TC-83) replicon expressing WN virus structural proteins for trans-complementation]. Efficient replication and expression of rabies G protein was demonstrated for the three constructs by transfection/infection of BHK-C(WN) and/or BHK-C-prM-E(WN) helper cells, as well as regular BHK cells, by immunostaining and immunofluorescence assay (IFA) using anti-Rabies G monoclonal antibody (RabG-Mab) (
Following inoculation in vivo individually, the WN(ΔC)-rabiesG s-PIV is expected to induce strong neutralizing antibody immune responses against both rabies and WN viruses, as well as T-cell responses. The WN(ΔprME)-rabiesG and WN(ΔCprME)-rabiesG PIVs will induce humoral immune response only against rabies because they do not encode the WN prM-E genes. WN(ΔC)-rabiesG s-PIV construct can be also co-inoculated with WN(ΔprME)-rabiesG construct in a d-PIV formulation (see in
The WN(ΔCprME)-rabiesG construct can be also used in a d-PIV formulation, if it is co-inoculated with a helper genome providing C-prM-E in trans (see in
Expression of RSV F Protein in WN s-PIV and d-PIV
Respiratory syncytial virus (RSV), member of Paramyxoviridae family, is the leading cause of severe respiratory tract disease in young children worldwide (Collins and Crowe, Respiratory Syncytial Virus and Metapneumovirus, In: Knipe et al. Eds., Fields Virology, 5th ed., Philadelphia: Wolters Kluwer/Lippincott Williams and Wilkins, 2007:1601-1646). Fusion protein F of the virus is a lead viral antigen for developing a safe and effective vaccine. To avoid post-vaccination exacerbation of RSV infection observed previously with a formalin-inactivated vaccine candidate, a balanced Th1/Th2 response to F is required which can be achieved by better TLR stimulation, a prerequisite for induction of high-affinity antibodies (Delgado et al., Nat. Med. 15:34-41, 2009), which should be achievable through delivering F in a robust virus-based vector. We have previously demonstrated the capacity of yellow fever virus-based chimeric LAV vectors to induce a strong, balanced Th1/Th2 response in vivo against an influenza antigen (WO 2008/036146). In the present invention, both yellow fever virus-based chimeric LAVs and PIV vectors are used for delivering RSV F to induce optimal immune response profile. Other LAVs and PIV vectors described herein can also be used for this purpose.
Full-length RSV F protein of A2 strain of the virus (GenBank accession number P03420) was codon optimized as described above, synthesized, and cloned into plasmids for PIV-WN s-PIV and d-PIV, using the insertion schemes shown in
It has been demonstrated that a C-terminally truncated, secreted form of RSV F could be more immunogenic than full-length protein (Li et al., J. Exp. Med. 188:681-688, 1998). Therefore, we also cloned the available truncated RSV F gene (see
Set forth below is the RSV amino acid sequence of the truncated construct. The chimeric West Nile/RSV-F signal peptide (ggktgiavi/melpiikanaittiliavtfcfass) is designed to be cleaved by signal protease after “ . . . fass”, releasing N-terminus of F2 “qnitee . . . ”. At the C-terminus is the sequence of autoprotease FMDV 2A fused to RSVF (nfdllklagdvesnpg). This sequence and/or only the RSV F protein portion thereof can be used in any of the vectors described herein. Further, this sequence (and/or only the RSV F protein portion thereof) can be the basis for derivation of analogs and fragments for use in the invention. Thus, sequences having percentage identities to this sequence, as described above, or fragments, as described above, can be used in the invention.
qniteefyqstc
nfdllklagdvesnpg
Based on the premise that protection can be obtained using a very limited, but focused antibody response, we have shown that a live vector expressing a codon optimized anchorless RSV F confers protection against RSV infection in an appropriate animal model and thus can be suitable for an infant vaccine.
NYVAC is a highly attenuated vaccinia strain with a series of deletion of virulence-associated or host-range genes of the Copenhagen strain (Tartaglia et al., Dev. Biol. Stand. 84:159-163, 1995). It has been used in a variety of pre-clinical and clinical studies and shown to be promising. Therefore, NYVAC has been included as a delivery vehicle for a comparative vaccine evaluation.
To generate the recombinant NYVAC expressing codon-optimized anchorless RSV F, IVR (in vitro recombination) was performed with CEF cells infected by parental NYVAC at M.O.I. of 10 and transfected with donor plasmid pLNZ16. Subsequently, IVR reaction products were serially diluted ten-fold from 1:103 to 1:106, and plated on CEF cells in 100-mm plates overlaid with medium-agarose without Blue-Gal. Three days after the first overlay, a second overlay containing Blue-Gal and Neutral Red was added. Blue plaques were picked and plaque purification continued until a white plaque was available for amplification. The isolated plaque went through three amplification steps, i.e., P1, P2, and P3.
The recombinant was fully characterized at P2 to confirm identity and purity. The NYVAC recombinant was designated vP2400.
Fowlpox is a member of the avipoxvirus genus and can cause disease in chickens and turkeys. Transmission of fowlpox virus is limited to avian species, with replication in mammalian cells resulting in abortive replication. The inability of fowlpox to produce infectious virus in mammalian cells renders fowlpox a very attractive vector for human vaccine development. The safety and efficacy of fowlpox-based vaccines have been investigated in a number of clinical trials for diseases such as cancer, HIV, and malaria. Preliminary results indicate that fowlpox vaccines are safe and well tolerated, and have demonstrated both immune and clinical efficacy. This vector was also used to compare delivery systems that express the RSV F gene product, and to allow a thorough evaluation of both immune efficacy and safety in relevant animal model systems.
To generate recombinant fowlpox expressing codon-optimized anchorless RSV F, IVR was performed with CEF cells infected by a parental fowlpox at M.O.I. of 10 and transfected with the donor plasmid pLNZ15 (Paoletti, Proc. Natl. Acad. Sci. U.S.A. 93:11349-11353, 1996). The rest of the steps are the same as above. The fowlpox recombinant was designated vFP2403.
Vero cells (˜1.5×106) were infected at an MOI of 10 with: Lanes 2 and 3, vP2400 (NYVAC-RSV F); Lanes 4 and 5, vFP2403 (fowlpox-RSV F); Lanes 6 and 7, PIV-F (ΔprME-RSVtrF); and Lanes 8 and 9, mock infected cells. All recombinant viruses express a codon optimized anchorless RSV F. Cell supernatants were harvested at 24 (Lanes 2, 4, 6, and 8) and 48 (Lanes 3, 5, 7, and 9) hours after infection. Equal amounts of the supernatant samples were analyzed by SDS-PAGE and the amount of RSV F present in each sample was determined using primary antibody, i.e., a mouse anti-RSV F (5353C75), followed by a goat anti-mouse IgG-horseradish peroxidase (HRP) conjugate as secondary antibody. The level of RSV F present in each sample was measured by comparison to a purified preparation of protein F from RSV-infected cells (2.5 ng, Lane 10) measured using a Kodak Imager Station 4000MM Pro. The results demonstrate that the amount of RSV F expressed in PIV-F infected Vero cells was significantly greater than that expressed by NYVAC and similar to that expressed by fowlpox.
For intramuscular immunization, Balb/c (6-8 weeks old) were injected bilaterally with 2×50 μl of PBS solution containing viral vectors expressing RSV F protein at two doses—either 106 or 107 PFU. Animals were boosted 4 weeks later with the same dose of the vaccine. Mice in control groups were immunized intranasally with 106 PFU RSV-Long strain or intramuscularly with an FI-RSV vaccine (100 μl) prepared according to the procedures used for the 1960's trials. Four weeks after boost, mice were challenged intranasally with either 2.2×106 PFU RSV-A2 (for RSVi27) or 107 PFU RSV-A2 (for RSVi32).
ELISA Analysis of Sera Derived from Vaccinated Mice (See
Immune sera were analyzed for anti-RSV-F IgG antibody titers using ELISA, which was performed with an immunoaffinity-purified full-length RSV protein (50 ng/ml) by two-fold dilutions of immune sera. Goat anti-mouse F(ab)2 IgG (H+L) conjugated to horseradish peroxidase was used as secondary antibody. The titer is a reciprocal of the last dilution at which the OD450 was greater than 0.1 and at least twice that of a control, to which no sample was added. It can be seen from
Vero cells were seeded onto 24-well plates (1.5×105 per well), incubated at 37° C. for two days. The neutralization reaction mixtures (serial diluted sera+virus+complement) were prepared in DMEM and incubated for 1 hour in a 37° C. shaker. The neutralization mixtures were added to the Vero cells. After a 2 hour incubation in a 37° C. shaker, the mixtures were removed and overlay media (methyl cellulose/DMEM) was added to each well. The infected Vero cells were incubated for 4 days at 37° C., then fixed with 80% methanol and stained with a primary antibody, i.e., a mouse anti-RSV F antibody (5353C75), followed by a goat anti-mouse IgG-horseradish peroxidase (HRP) conjugate as secondary antibody. The plaques were counted by eye and neutralizing titers were expressed as the dilution that caused 60% plaque reduction.
It can be seen from
1Single dose, IC inoculation, ICR 5-day old mice, graded log doses administered.
2AST for mice that died; na, not applicable.
1IP immunization (d0 prime, and d21 boost in select groups); challenge on d35: wt WN NY99, 3 log10 PFU IP, 270 LD50; wt YF Asibi, 3 log10 PFU IC, 500 LD50; N/D, not determined.
1Syrian hamsters, SC inoculation (d0, and d21 in select groups); challenge (d39): wt WN NY385/99 6 log10 PFU IP, wt JE Nakayama 5.8 log10 PFU IC, or hamster-adapted YF Asibi 7 log10 PFU IP (McArthur et al., J. Virol. 77: 1462-1468, 2003; McArthur et al., Virus Res. 110: 65-71, 2005).
1C57/BL6 mice, IP inoculations on days 0 and 21; pooled serum PRNT titers.
1AST for mice that died.
1Numbers in parenthesis correspond to number of mice in each pooled serum sample tested.
2Mortalities on day 9 are shown.
All publications, patent applications, and patents mentioned in this specification are incorporated herein by reference in their entirety as if each individual publication, patent application, or patent were specifically and individually indicated to be incorporated by reference.
Various modifications and variations of the described viruses, vectors, compositions, and methods of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention that are obvious to those skilled in the fields of medicine, pharmacology, or related fields are intended to be within the scope of the invention. Use of singular forms herein, such as “a” and “the,” does not exclude indication of the corresponding plural form, unless the context indicates to the contrary. Similarly, use of plural terms does not exclude indication of a corresponding singular form. Other embodiments are within the scope of the following claims.
What is claimed is:
TCA CTT ATA ATT ACA GCC ATC ATA TTC ATA GCC TCG GCA AAC CAC AAA GTC ACA
This application claims benefit of U.S. provisional application No. 61/210,305, filed Mar. 16, 2009, the contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US10/27552 | 3/16/2010 | WO | 00 | 1/30/2012 |
| Number | Date | Country | |
|---|---|---|---|
| 61210305 | Mar 2009 | US |
