Patent Application
20200276297
A global study has found that RSV is one of the most common causes of infant hospitalization due to acute lower respiratory tract infections (ALRI) in children younger than 5 years of age in the US and worldwide, resulting in up to 200,000 deaths. RSV was associated with hospitalizations 16-times more than influenza in children under one year of age. In addition to hospitalization, RSV resulted in higher rates of emergency department visits and required more caregiver time and resource utilization than influenza.
Currently, several RSV vaccine candidates are under development or clinical trials targeting different age groups. Both live attenuated and killed vaccines have been attempted, but without much success. Recombinant viral vectors, such as recombinant vesicular stomatitis virus (rVSV), adenovirus, etc., provide powerful technologies for delivering heterologous antigens (antigens from different viruses) with minimal disadvantages. What is needed in the art is an efficacious rVSV vector based anti-RSV vaccine that safely used in humans to prevent RSV infections.
Disclosed herein are compositions comprising a recombinant viral vector and one or more respiratory syncytial virus (RSV) proteins.
Also disclosed herein are methods of using the immunogenic compositions and vaccines disclosed herein. For example, disclosed are methods of eliciting an immune response against RSV in a subject, the method comprising administering to the subject a composition or vaccine as disclosed herein.
The present invention can be understood more readily by reference to the following detailed description of the invention and the Examples included therein.
All patents, patent applications, and publications cited herein, whether supra or infra, are hereby incorporated by reference in their entireties into this application in order to more fully describe the state of the art as known to those skilled therein as of the date of the invention described and claimed herein.
Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used in the description of the embodiments herein is for describing particular embodiments only and is not intended to be limiting of the embodiments disclosed. As used in the description, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.
Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in this disclosure are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this disclosure are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of any claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values described herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. It is also understood that when a value is disclosed that “less than or equal to” the value, “greater than or equal to the value” and possible ranges between values are also disclosed, as appropriately understood by the skilled artisan. For example, if the value “10” is disclosed the “less than or equal to 10” as well as “greater than or equal to 10” is also disclosed. It is also understood that throughout the application, data are provided in a number of different formats, and that these data, represent endpoints, starting points, and ranges for any combination of the data points. For example, if a particular data point “10” and a particular data point 15 are disclosed, it is understood that greater than, greater than or equal to, less than, less than or equal to, and equal to 10 and 15 are considered disclosed as well as between 10 and 15. It is also understood that each unit between two particular units is also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.
As used herein, the term “amino acid sequence” refers to a list of abbreviations, letters, characters or words representing amino acid residues. The amino acid abbreviations used herein are conventional one letter codes for the amino acids and are expressed as follows: A, alanine; C, cysteine; D aspartic acid; E, glutamic acid; F, phenylalanine; G, glycine; H histidine; I isoleucine; K, lysine; L, leucine; M, methionine; N, asparagine; P, proline; Q, glutamine; R, arginine; S, serine; T, threonine; V, valine; W, tryptophan; Y, tyrosine.
“Polypeptide” as used herein refers to any peptide, oligopeptide, polypeptide, gene product, expression product, or protein. A polypeptide is comprised of consecutive amino acids. The term “polypeptide” encompasses naturally occurring or synthetic molecules. The terms “polypeptide,” “peptide,” and “protein” can be used interchangeably.
In addition, as used herein, the term “polypeptide” refers to amino acids joined to each other by peptide bonds or modified peptide bonds, e.g., peptide isosteres, etc. and may contain modified amino acids other than the 20 gene-encoded amino acids. The polypeptides can be modified by either natural processes, such as post-translational processing, or by chemical modification techniques which are well known in the art. Modifications can occur anywhere in the polypeptide, including the peptide backbone, the amino acid side-chains and the amino or carboxyl termini. The same type of modification can be present in the same or varying degrees at several sites in a given polypeptide. Also, a given polypeptide can have many types of modifications. Modifications include, without limitation, acetylation, acylation, ADP-ribosylation, amidation, covalent cross-linking or cyclization, covalent attachment of flavin, covalent attachment of a heme moiety, covalent attachment of a nucleotide or nucleotide derivative, covalent attachment of a lipid or lipid derivative, covalent attachment of a phosphytidylinositol, disulfide bond formation, demethylation, formation of cysteine or pyroglutamate, formylation, gamma-carboxylation, glycosylation, GPI anchor formation, hydroxylation, iodination, methylation, myristolyation, oxidation, pergylation, proteolytic processing, phosphorylation, prenylation, racemization, selenoylation, sulfation, and transfer-RNA mediated addition of amino acids to protein such as arginylation. (See Proteins—Structure and Molecular Properties 2nd Ed., T. E. Creighton, W.H. Freeman and Company, New York (1993); Posttranslational Covalent Modification of Proteins, B. C. Johnson, Ed., Academic Press, New York, pp. 1-12 (1983)).
As used herein, “isolated polypeptide” or “purified polypeptide” is meant to mean a polypeptide (or a fragment thereof) that is substantially free from the materials with which the polypeptide is normally associated in nature. The polypeptides of the invention, or fragments thereof, can be obtained, for example, by extraction from a natural source (for example, a mammalian cell), by expression of a recombinant nucleic acid encoding the polypeptide (for example, in a cell or in a cell-free translation system), or by chemically synthesizing the polypeptide. In addition, polypeptide fragments may be obtained by any of these methods, or by cleaving full length proteins and/or polypeptides.
The phrase “nucleic acid” as used herein refers to a naturally occurring or synthetic oligonucleotide or polynucleotide, whether DNA or RNA or DNA-RNA hybrid, single-stranded or double-stranded, sense or antisense, which is capable of hybridization to a complementary nucleic acid by Watson-Crick base-pairing. Nucleic acids of the invention can also include nucleotide analogs (e.g., BrdU), and non-phosphodiester internucleoside linkages (e.g., peptide nucleic acid (PNA) or thiodiester linkages). In particular, nucleic acids can include, without limitation, DNA, RNA, cDNA, gDNA, ssDNA, dsDNA or any combination thereof.
As used herein, “isolated nucleic acid” or “purified nucleic acid” is meant to mean DNA that is free of the genes that, in the naturally-occurring genome of the organism from which the DNA of the invention is derived, flank the gene. The term therefore includes, for example, a recombinant DNA which is incorporated into a vector, such as an autonomously replicating plasmid or virus; or incorporated into the genomic DNA of a prokaryote or eukaryote (e.g., a transgene); or which exists as a separate molecule (for example, a cDNA or a genomic or cDNA fragment produced by PCR, restriction endonuclease digestion, or chemical or in vitro synthesis). It also includes a recombinant DNA which is part of a hybrid gene encoding additional polypeptide sequence. The term “isolated nucleic acid” also refers to RNA, e.g., an mRNA molecule that is encoded by an isolated DNA molecule, or that is chemically synthesized, or that is separated or substantially free from at least some cellular components, for example, other types of RNA molecules or polypeptide molecules.
As used herein, “sample” is meant to mean an animal; a tissue or organ from an animal; a cell (either within a subject, taken directly from a subject, or a cell maintained in culture or from a cultured cell line); a cell lysate (or lysate fraction) or cell extract; or a solution containing one or more molecules derived from a cell or cellular material (e.g. a polypeptide or nucleic acid), which is assayed as described herein. A sample can also be any body fluid or excretion (for example, but not limited to, blood, urine, stool, saliva, tears, bile) that contains cells or cell components.
Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosure, suitable methods and materials are described below. The term “comprises” means “includes.” Thus, unless the context requires otherwise, the word “comprises,” and variations such as “comprise” and “comprising” will be understood to imply the inclusion of a stated compound or composition (e.g., nucleic acid, polypeptide, antigen) or step, or group of compounds or steps, but not to the exclusion of any other compounds, composition, steps, or groups thereof.
An “immunogenic composition” is a composition of matter suitable for administration to a human or animal subject (e.g., in an experimental setting) that is capable of eliciting a specific immune response, e.g., against a pathogen, such as RSV. As such, an immunogenic composition includes one or more antigens (for example, whole purified virus or antigenic subunits, e.g., polypeptides, thereof) or antigenic epitopes. An immunogenic composition can also include one or more additional components capable of eliciting or enhancing an immune response, such as an excipient, carrier, and/or adjuvant. In certain instances, immunogenic compositions are administered to elicit an immune response that protects the subject against symptoms or conditions induced by a pathogen. In some cases, symptoms or disease caused by a pathogen is prevented (or treated, e.g., reduced or ameliorated) by inhibiting replication of the pathogen following exposure of the subject to the pathogen. In the context of this disclosure, the term immunogenic composition will be understood to encompass compositions that are intended for administration to a subject or population of subjects for the purpose of eliciting a protective or palliative immune response against the virus (that is, vaccine compositions or vaccines).
The term “purification” (e.g., with respect to a pathogen or a composition containing a pathogen) refers to the process of removing components from a composition, the presence of which is not desired. Purification is a relative term, and does not require that all traces of the undesirable component be removed from the composition. In the context of vaccine production, purification includes such processes as centrifugation, dialization, ion-exchange chromatography, and size-exclusion chromatography, affinity-purification or precipitation. Thus, the term “purified” does not require absolute purity; rather, it is intended as a relative term. Thus, for example, a purified virus preparation is one in which the virus is more enriched than it is in its generative environment, for instance within a cell or population of cells in which it is replicated naturally or in an artificial environment. A preparation of substantially pure viruses can be purified such that the desired virus or viral component represents at least 50% of the total protein content of the preparation. In certain embodiments, a substantially pure virus will represent at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, or at least 95% or more of the total protein content of the preparation.
An “isolated” biological component (such as a virus, nucleic acid molecule, protein or organelle) has been substantially separated or purified away from other biological components in the cell and/or organism in which the component occurs or is produced. Viruses and viral components, e.g., proteins, which have been “isolated” include viruses, and proteins, purified by standard purification methods. The term also embraces viruses and viral components (such as viral proteins) prepared by recombinant expression in a host cell.
An “antigen” is a compound, composition, or substance that can stimulate the production of antibodies and/or a T cell response in an animal, including compositions that are injected, absorbed or otherwise introduced into an animal. The term “antigen” includes all related antigenic epitopes. The term “epitope” or “antigenic determinant” refers to a site on an antigen to which B and/or T cells respond. The “dominant antigenic epitopes” or “dominant epitope” are those epitopes to which a functionally significant host immune response, e.g., an antibody response or a T-cell response, is made. Thus, with respect to a protective immune response against a pathogen, the dominant antigenic epitopes are those antigenic moieties that when recognized by the host immune system result in protection from disease caused by the pathogen. The term “T-cell epitope” refers to an epitope that when bound to an appropriate MHC molecule is specifically bound by a T cell (via a T cell receptor). A “B-cell epitope” is an epitope that is specifically bound by an antibody (or B cell receptor molecule). An antigen can also affect the innate immune response.
An “immune response” is a response of a cell of the immune system, such as a B cell, T cell, or monocyte, to a stimulus. An immune response can be a B cell response, which results in the production of specific antibodies, such as antigen specific neutralizing antibodies. An immune response can also be a T cell response, such as a CD4+ response or a CD8+ response. In some cases, the response is specific for a particular antigen (that is, an “antigen-specific response”). An immune response can also include the innate response. If the antigen is derived from a pathogen, the antigen-specific response is a “pathogen-specific response.” A “protective immune response” is an immune response that inhibits a detrimental function or activity of a pathogen, reduces infection by a pathogen, or decreases symptoms (including death) that result from infection by the pathogen. A protective immune response can be measured, for example, by the inhibition of viral replication or plaque formation in a plaque reduction assay or ELISA-neutralization assay, or by measuring resistance to pathogen challenge in vivo.
The immunogenic compositions disclosed herein are suitable for preventing, ameliorating and/or treating disease caused by infection of the virus.
By “reduce” or other forms of the word, such as “reducing” or “reduction,” is meant lowering of an event or characteristic (e.g., viral infection). It is understood that this is typically in relation to some standard or expected value, in other words it is relative, but that it is not always necessary for the standard or relative value to be referred to. For example, “reduces viral infection” means decreasing the amount of virus relative to a standard or a control.
By “prevent” or other forms of the word, such as “preventing” or “prevention,” is meant to stop a particular event or characteristic, to stabilize or delay the development or progression of a particular event or characteristic, or to minimize the chances that a particular event or characteristic will occur. Prevent does not require comparison to a control as it is typically more absolute than, for example, reduce. As used herein, something could be reduced but not prevented, but something that is reduced could also be prevented. Likewise, something could be prevented but not reduced, but something that is prevented could also be reduced. It is understood that where reduce or prevent are used, unless specifically indicated otherwise, the use of the other word is also expressly disclosed.
As used herein, “treatment” refers to obtaining beneficial or desired clinical results. Beneficial or desired clinical results include, but are not limited to, any one or more of: alleviation of one or more symptoms (such as infection), diminishment of extent of infection, stabilized (i.e., not worsening) state of infection, preventing or delaying spread of the infection, preventing or delaying occurrence or recurrence of infection, and delay or slowing of infection progression.
The term “patient” preferably refers to a human in need of treatment with an antibiotic or treatment for any purpose, and more preferably a human in need of such a treatment to treat viral infection. However, the term “patient” can also refer to non-human animals, preferably mammals such as dogs, cats, horses, cows, pigs, sheep and non-human primates, among others, that are in need of treatment with antibiotics.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Every numerical range given throughout this specification will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein.
In addition, where features or aspects of the inventions are described in terms of Markush groups or other grouping of alternatives, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group or other group.
RSV has four major structural proteins (glycoprotein [G], fusion [F] protein, Nucleoprotein [N] and M2-1) which are responsible for induction of humoral and cell mediated immune responses in the infected individual. Humoral (or antibody mediated) immunity is required for neutralizing/limiting the virus spread, whereas, cell mediated immunity is required for clearance of the virus from the body of the infected individual. G and F are surface proteins and induce both neutralizing antibodies and T cell mediated immune responses. N and M2-1 are internal proteins and contribute in induction of T cell response.
Four types of recombinant VSVs have been developed, each individually expressing one of the four above mentioned antigenic structural proteins (modified or unmodified) between glycoprotein (G) and polymerase (L) protein genes of the rVSV vector (
It is noted that viruses other than RSV can be used with the rVSV platforms disclosed herein. Examples of other viruses are known to those of skill in the art and include other respiratory (human and animal) viruses such as, human metapneumo virus, influenza, and bRSV.
RSV F protein is involved in the fusion of the virus to the cell membrane of the infected cell and has a higher number of neutralizing epitopes, antigenic sites and T-cell epitopes than G protein, thus, making it an attractive vaccine candidate. F protein exists in two different structural conformations, pre-fusion and post-fusion (Pre-F and Post-F), and Pre-F has been shown to be more immunogenic than Post-F. Therefore, wildtype F and Pre-F genes have been cloned in rVSV (Table 2). The codon-optimized F gene in rVSV can also be cloned. Disclosed herein are various formats of F-protein, including codon-optimized F protein, pre-fusion conformation stabilized F-protein, and post-fusion F protein. The F protein can be wildtype or codon-optimized.
Further, N and M2-1 proteins have been shown to contain several putative sites of T-cell epitopes inducing cell mediated immunity, which is responsible for clearance of the infective RSV virus from the body. Therefore, rVSVs expressing M2-1 and different segments of the N gene have been cloned and recovered (Table 3).
When a human or non-human animal is challenged by a foreign organism/pathogen the challenged individual responds by launching an immune response which may be protective. This immune response is characterized by the coordinated interaction of the innate and acquired immune response systems.
The innate immune response forms the first line of defense against a foreign organism/pathogen. An innate immune response can be triggered within minutes of infection in an antigen-independent, but pathogen-dependent, manner. The innate, and indeed the adaptive, immune system can be triggered by the recognition of pathogen associated molecular patterns unique to microorganisms by pattern recognition receptors present on most host cells. Once triggered the innate system generates an inflammatory response that activates the cellular and humoral adaptive immune response systems.
The adaptive immune response becomes effective over days or weeks and provides the antigen specific responses needed to control and usually eliminate the foreign organism/pathogen. The adaptive response is mediated by T cells (cell mediated immunity) and B cells (antibody mediated or humoral immunity) that have developed specificity for the pathogen. Once activated these cells have a long lasting memory for the same pathogen.
The ability of an individual to generate immunity to foreign organisms/pathogens, thereby preventing or at least reducing the chance of infection by the foreign organism/pathogen, is a powerful tool in disease control and is the principle behind vaccination.
Vaccines function by preparing the immune system to mount a response to a pathogen. Typically, a vaccine comprises an antigen, which is a foreign organism/pathogen or a toxin produced by an organism/pathogen, or a portion thereof, that is introduced into the body of a subject to be vaccinated in a non-toxic, and/or non-pathogenic form. The antigen in the vaccine causes the subject's immune system to be “primed” or “sensitized” to the organism/pathogen from which the antigen is derived. Subsequent exposure of the immune system of the subject to the organism/pathogen or toxin results in a rapid and robust specific immune response, that controls or destroys the organism/pathogen or toxin before it can multiply and infect or damage enough cells in the host organism to cause disease symptoms.
Disclosed herein are multiple rVSVs expressing one of the four different antigenic proteins (in natural or modified conformation) of RSV, which have been shown to be efficacious in a cotton rat animal model, with or without combining with an adjuvant expressing rVSV (rVSV-Hsp70). It has been demonstrated that when delivered intranasally, rVSVs expressing RSV proteins induce protective immunity in vaccinated cotton rats against wildtype RSV challenge.
Specifically, disclosed herein are compositions comprising a recombinant viral vector and one or more respiratory syncytial virus (RSV) proteins. The recombinant viral vector can be selected from recombinant viral vectors known to those of skill in the art. Non-limiting examples of vectors that can be used include viral-based vectors, such as those described in Lundstrom et al. (Vaccines 2016, 4, 39), hereby incorporated by reference in its entirety for its teaching concerning viral vectors (e.g., retrovirus, adenovirus, adeno-associated virus, lentivirus, HMPV, PIV). Examples of rVSV that can be used include, but are not limited to the expression of G and F in one vector, G and N sequences or an expression of an RSV gene and HSP as adjuvant. HSP can be human or other.
As mentioned above and in Example 1, there are four categories of RSV proteins which can be used in the compositions disclosed herein. It is noted that RSV can be from any source, such as human, bovine, etc. The RSV proteins include the G protein, the F protein, the M2-1 protein, and the N protein. Further, the G protein is present in two forms, the membrane bound (mG) and secretory (sG) forms. Either form can be used with the compositions and methods disclosed herein. These proteins can be used alone in the composition, or can be presented together to increase the antigenic response. For example, the G protein can be coupled with N, M2-1, or F proteins. The mG protein can be coupled with N, M2-1, or F proteins. Any of these proteins can be combined in any possible permutation for use in an immunogenic composition or vaccine. The RSV proteins used in the compositions and vaccines disclosed herein can be full length, or can be functional immunogenic fragments that retain their immunogenicity when administered to a subject. One of skill in the art will readily understand how to obtain immunogenic fragments of an RSV protein.
Furthermore, the proteins disclosed herein can be codon optimized. For example, the codon optimization of G and pre-fusion conformation stabilized F leads to higher and more stable expression of these proteins. Sequences are listed in the sequences listing. “Codon optimization” is defined as modifying a nucleic acid sequence for enhanced expression in the cells of the vertebrate of interest, e.g. human, by replacing at least one, more than one, or a significant number, of codons of the native sequence with codons that are more frequently or most frequently used in the genes of that vertebrate. Various species exhibit particular bias for certain codons of a particular amino acid.
The composition disclosed herein can also comprise one or more adjuvants. As used herein, “adjuvant” is understood as an aid or contributor to increase the efficacy or potency of a vaccine or in the prevention, amelioration, or cure of disease by increasing the efficacy or potency of a therapeutic agent as compared to a vaccine or agent administered without the adjuvant. An increase in the efficacy or potency can include a decrease in the amount of vaccine or agent to be administered, a decrease in the frequency and/or number of doses to be administered, or a more rapid or robust response to the agent or vaccine (i.e., higher antibody titer). The adjuvant can be HSP70 (see
Described herein are vaccines comprising a composition of this invention in a carrier wherein the vaccine is protective against RSV infection. The term “immunogenic carrier” as used herein can refer to a first polypeptide or fragment, variant, or derivative thereof which enhances the immunogenicity of a second polypeptide or fragment, variant, or derivative thereof. An “immunogenic carrier” can be fused, to or conjugated/coupled to the desired polypeptide or fragment thereof. See, e.g., European Patent No. EP 0385610 B1, which is incorporated herein by reference in its entirety for its teaching of fusing, conjugating or coupling a polypeptide to a carrier. An example of an “immunogenic carrier” is PLGA.
The vaccine composition of the present invention may also be co-administered with antigens from other pathogens as a multivalent vaccine.
Also disclosed herein are methods of using the immunogenic compositions and vaccines disclosed herein. For example, disclosed are methods of eliciting an immune response against RSV in a subject, the method comprising administering to the subject a composition or vaccine as disclosed herein. The immune response can be protective against RSV, for example.
Also disclosed is a method of reducing symptoms or duration of RSV in a subject, the method comprising the steps of: (a) providing a composition of any of claims 1 to 15 or the vaccine of claim 16; and (b) administering said composition or vaccine to the subject, thereby reducing symptoms or duration of RSV.
Further disclosed is a method of stimulating an immune response in a subject, the method comprising: administering to said subject a composition or vaccine as disclosed herein.
The vaccines disclosed herein can be administered in a variety of ways, and at a variety of doses. For example, intranasal route, orally, intramuscular route, intradermal and subcutaneous injection as well as application by ocular, vaginal and anal route.
In one example, a single dose of the immunogenic composition or vaccine can be given, wherein the composition comprises about 1×105 or more particles (which also are referred to as particle units (pu)) of the composition, e.g., about 1×106 or more particles, about 1×10′ or more particles, about 1×108 or more particles, about 1×109 or more particles, or about 3×108 or more particles of the composition. Alternatively, or in addition, a single dose of the composition comprises about 3×1014 particles or less of the immunogenic composition, e.g., about 1×1013 particles or less, about 1×1012 particles or less, about 3×1011 particles or less, about 1×1011 particles or less, about 1×1010 particles or less, or about 1×109 particles or less of the immunogenic composition. Thus, a single dose of immunogenic composition can comprise a quantity of particles of the immunogenic composition in a range defined by any two of the aforementioned values. For example, a single dose of immunogenic composition can comprise 1×105-1×1014 particles, 1×107-1×1012 particles, 1×108-1×1011 particles, 3×108-3×10″ particles, 1×109-1×1012 particles, 1×109-1×1011 particles, 1×109-1×1010 particles, or 1×1010-1×1012 particles, of the immunogenic composition. In other words, a single dose of immunogenic composition can comprise, for example, about 1×106 pu, 2×106 pu, 4×106 pu, 1×107 pu, 2×107 pu, 4×107 pu, 1×108 pu, 2×108 pu, 3×108 pu, 4×108 pu, 1×109 pu, 2×109 pu, 3×109 pu, 4×109 pu, 1×1010 pu, 2×1010 pu, 3×1010 pu, 4×1010 pu, 1×1011 pu, 2×1011 pu, 3×1011 pu, 4×1011 pu, 1×1012 pu, 2×1012 pu, 3×1012 pu, or 4×1012 pu of the adenoviral vector.
The vaccine can be given in single doses, or two doses which are separated. For example, when two doses are given, they can be given 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days apart. The vaccine can be administered in a variety of ways known to those of skill in the art, such as intranasally.
Since 105 TCID50/dose of the RSV induced protective immunity in cotton rats (n=4 per group), therefore, for relative comparison of rVSVs with the RSV immune efficacy of the rVSV-G and rVSV-F recombinants, 105 pfu (plaque forming unit)/dose as the starting dose and also immunized with higher/10 fold incremental doses (106 pfu/animal or 107 pfu/animal) were evaluated. Cotton rats were immunized with either individual rVSV-G or rVSV-F recombinant or in combination (rVSV-G+F). The hypothesis was that rVSV induced protective effect is dose dependent and further, enhanced effect is possible by combining both G and F expressing rVSVs. Immunized animals were challenged with wild type RSV strain A2 (dose: 105 TCID50) four weeks after vaccination and euthanized the animals four days after challenge. Clearance of the challenge virus was evaluated (by titrating the amount of virus using a cell culture cytopathic effect based assay) from the lower and upper respiratory tract (LRT and URT) represented by homogenates of the lungs and nasal passage respectively (collected on the day of euthanization) and virus neutralizing (VN) antibody levels (by cell culture based virus neutralization test) in the serum sample collected on the day of challenge. These studies demonstrated that non-invasive mucosal delivery of the rVSV-G or F by intranasal route was more effective than parental (by subcutaneous) route of administration. Therefore, for all subsequent studies, intranasal immunization method was employed. Further, it was also shown that 105 pfu/animal of either rVSV-G or rVSV-F was effective in clearance of challenge virus from the LRT but not URT along with lower VN antibody levels. Therefore, the objective of this study was to extend the protection to URT and enhance the VN antibody levels by employing higher dose and combined vaccination strategy.
The results indicated that, higher (each rVSV at 107 pfu/dose/cotton rat[CR]) and combined (rVSV-G+F) immunization strategy was effective in inducing protective immunity which could clear the challenge RSV from both LRT and URT (
These results and the comparison of VSV expressing either G or F with immunization results through immunization with purified G and post-fusion F protein (Table 4) demonstrate that VSV vectors deliver a better immune response.
Though 107 pfu dose of rVSV-G and rVSV-F combination was adequate to protect the immunized cotton rats from the challenge virus, virus neutralization (VN) antibody titers were still lower than RSV-A2 immunized animals (which showed higher VN titer titers, ≥28). Therefore, to enhance the VN titers in rVSV immunized groups, it was hypothesized that by following prime-boost regimen of immunization strategy, VN titers can be significantly enhanced with high (107 pfu) and possibly with low dose (105 pfu) immunization as well. Therefore, cotton rats were immunized with either high dose or low dose of rVSVs, individually or in combination, and the booster dose was administered three weeks after primary immunization and the immunized cotton rats were challenged three weeks after booster immunization.
The results indicated that, at low dose immunization, neither individual nor combined rVSVs induced protective immunity in URT, and VN titers were also not considerably improved upon booster immunization. Whereas, in higher dose immunization groups, in all three groups VN antibodies were enhanced after booster immunization (
Immunization can also be improved through the use of a VSV expressing HSP70 which functions as an adjuvant (
Though prime-boost immunization with rVSV-G+F enhanced the VN titers (titer: ˜26), however, the VN titers in RSV-A2 immunized animals were significantly higher (titer: >28). Therefore, with an objective to further enhancing the protective immunity in the rVSV-G+F immunized animals and to explore a possibility of extending the longevity of the protection, the vaccine rVSV candidates were combined with Hsp70 expressing rVSV (rVSV-Hsp-70). It has been demonstrated that rVSV-Hsp70 enhanced adjuvanticity of the vaccine antigen co-expressing rVSV (Ma, et al., 2014) resulting in enhanced mucosal immunity. Further the safe dose of rVSV-Hsp70 (i. e., ≤107 pfu/dose/CR) has been shown in cotton rats. Therefore, in the present study, with an objective to identify the appropriate dose of rVSV-Hsp70 along with rVSV-G+F, cotton rats were immunized (following prime-boost regimen) with either high dose or low dose combination of rVSV-G+F and combined with one of the three doses (105, 106, or 107 pfu/dose/CR) of the rVSV-Hsp70.
The results indicated that, 105 pfu dose of the rVSV-Hsp70 was an appropriate dose along with high dose of the rVSV-G+F as there was complete protection of both LRT and URT (
It is clearly evident from the above studies that, prime-boost immunization of the 107 pfu dose of each of rVSV-G and rVSV-F combination induced enhanced protective immunity in the cotton rat model. Further, efficacy of the combination (and possibly longevity of the protection) can be further enhanced by inclusion of the adjuvant expressing rVSV-Hsp70.
In order to identify an effective G protein candidate, several modifications were made to the G protein to enhance its immunogenicity as explained in table 1 (S. No. 2-9) and expressed the indicated G variant in the VSV vector and tested the efficacy in the cotton rats. Cotton rats were immunized with each of the seven recovered rVSV G variants, following the previously established strategy for the rVSV-G+F immunization studies (i. e., high dose [107 pfu/dose/CR] and prime-boost immunization).
The results clearly indicated that among all the tested G variants, two recombinants (rVSV-cG and rVSV-mG) were successful in inducing protective immunity in the in the URT (
This application claims benefit of U.S. Provisional Application No. 62/559,167, filed Sep. 15, 2017, which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/051054 | 9/14/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62559167 | Sep 2017 | US |
