Genetically stable live attenuated respiratory syncytial virus vaccine and its production
Inventors
Collins, Peter L. • Luongo, Cindy L. • Buchholz, Ursula J. • Murphy, Brian R.
Assignees
US Department of Health and Human Services
Publication Number
US-10307476-B2
Publication Date
2019-06-04
Expiration Date
2033-03-13
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Abstract
Provided herein are recombinant respiratory syncytial viruses that contain mutations that make the disclosed viruses attractive vaccine candidates. The viruses disclosed contain attenuating mutations designed to have increased genetic and phenotypic stability. Desired combinations of these mutations can be made to achieve desired levels of attenation. Exemplary vaccine candidates are described. Also provided are polynucleotides capable of encoding the described viruses, as wells as methods for producing the viruses and methods of use.
Core Innovation
The invention provides recombinant respiratory syncytial viruses (RSVs) containing specific attenuating mutations designed to have increased genetic and phenotypic stability, making them attractive vaccine candidates. These mutations can be combined to achieve desired levels of attenuation. The RSVs include mutations in codons encoding amino acid residues of the large polymerase protein (L), notably at positions 1313 and 1321, which historically have shown stability issues in clinical trials. Alternative codon assignments or deletions at these sites result in viruses with improved genetic stability and controlled attenuation.
The problem addressed is the difficulty in developing live-attenuated RSV vaccines due to moderate RSV growth titers, instability of attenuating mutations that can revert to wild-type or less attenuated forms, and balancing attenuation with immunogenicity. Previous vaccines derived biologically were under- or over-attenuated and exhibited genetic instability. Stabilizing mutations at positions 1321 and 1313 in the L protein reduce the risk of phenotypic reversion while preserving desirable attenuation and immunogenic qualities. Also disclosed are methods for producing the viruses and associated polynucleotides, as well as methods for enhancing genetic stability of attenuated strains by identifying and preventing reversion mutations.
Claims Coverage
The patent claims cover recombinant infectious respiratory syncytial viruses incorporating key mutations and deletions, focusing on stabilizing and attenuating changes to the L protein and other viral components. The main inventive features include specific codon deletions and substitutions that confer increased genetic stability and controlled attenuation.
Recombinant RSV with deletion of codon encoding serine at L protein position 1313
A recombinant infectious respiratory syncytial virus having a deletion of the codon encoding serine at position 1313 of the large polymerase protein (L), optionally including various other viral proteins, resulting in an attenuated virus.
Mutation of codon encoding tyrosine at L protein position 1321 for attenuation and stability
The RSV genome or antigenome further comprises a mutation at codon 1321 of the L protein, including specific mutations such as AAA codon encoding lysine, combined optionally with other mutations and deletions to enhance attenuation and genetic stability.
Combination of mutations and gene deletions for improved vaccine candidates
The virus further comprises combinations of mutations including L protein mutations (1321K, 1321E, 1321P, 1321G), a Q831L mutation, cold passage mutations in N, F, and L proteins, a specific gene-start signal substitution at the M2 gene, and deletion of SH or NS2 genes, enhancing safety and efficacy as a vaccine.
Mutation of amino acid residue 1314 of L protein to leucine
A mutation at amino acid 1314 of the L protein substituting leucine for isoleucine, encoded by the codon CTG, which provides an attenuated and genetically stable virus, optionally combined with the above mutations and deletions.
Use of recombinant RSV with described mutations for inducing immune response
Method of producing an immune response in an animal by administering the recombinant RSV comprising the described deletions and mutations via various routes including injection, aerosol, nasal, oral, or topical application, applicable to mammals including humans.
The claims encompass recombinant RSVs with deletions and mutations in the L protein at positions 1313 and 1321 and other specific loci, alone or in combination with gene deletions and attenuating mutations, enabling genetically stable, attenuated RSV vaccine candidates and methods of their use for immunization.
Stated Advantages
The mutations confer increased genetic and phenotypic stability preventing reversion to wild-type or less attenuated forms.
The recombinant RSVs exhibit temperature-sensitive growth characteristics and attenuated replication, improving safety as live vaccines.
The viruses maintain efficient replication at permissive temperatures, facilitating vaccine manufacture.
Multiple combinations of mutations allow calibration of attenuation to balance immunogenicity and safety.
The stabilized mutations reduce mutation-induced phenotypic changes observed in previous vaccine candidates, improving consistency and reliability.
Documented Applications
Use as live attenuated vaccines for inducing protective immune responses against RSV infection in mammals, including humans.
Administration via injection, aerosol, nasal spray, nasal droplets, oral inoculation, or topical application.
Use in vaccine formulations for pediatric and other susceptible populations to prevent or reduce RSV-related morbidity and mortality.
Delivery vectors for nonviral proteins such as cytokines to mammals.
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