Construction of West Nile virus and dengue virus chimeras for use in a live virus vaccine to prevent disease caused by West Nile virus
Inventors
Pletnev, Alexander G. • Putnak, Joseph R. • Chanock, Robert M. • Murphy, Brian R. • Whitehead, Stephen S. • Blaney, Jr., Joseph E.
Assignees
Walter Reed Army Institute of Research • US Department of Health and Human Services
Publication Number
US-8778671-B2
Publication Date
2014-07-15
Expiration Date
2023-01-09
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Abstract
The present invention relates to attenuated, immunogenic West Nile virus chimeras built on a dengue virus backbone for the production of immunogenic, live, attenuated West Nile virus vaccines.
Core Innovation
The invention relates to attenuated, immunogenic chimeric viruses constructed by replacing the structural protein genes of a dengue virus backbone with corresponding structural protein genes from West Nile virus. Specifically, chimeras contain the nonstructural protein genes and genome backbone of dengue virus, particularly dengue type 4 (DEN4), into which the premembrane/membrane (prM) and envelope (E) protein genes of West Nile virus are substituted. These chimeric viruses are live, attenuated, immunogenic, and useful as vaccine candidates providing immunity against West Nile virus infection without causing disease symptoms.
The problem addressed by the invention relates to the emergence and spread of West Nile virus (WN), which causes disease ranging from mild symptoms to severe neurological illness and death in humans. There is currently no licensed human vaccine for West Nile virus, and mosquito control is inadequate as a prevention strategy. Existing attenuated live dengue virus vaccines are insufficiently characterized and have risks of reversion to virulence. Thus, there is a need for safe, effective, and genetically stable flavivirus vaccines that confer protection against West Nile virus. The invention offers a solution by producing a live attenuated West Nile virus vaccine based on a dengue virus backbone with defined mutations that achieve attenuation and immunogenicity.
The detailed description discloses that viable chimeras were constructed by substituting the prM and E genes of West Nile virus strain NY99 into a dengue type 4 virus genome backbone containing an attenuating 30-nucleotide deletion in the 3′ untranslated region (3′ UTR). Specific sequence motifs at the capsid/prM cleavage site were found essential for virus viability. The chimeric viruses exhibit markedly reduced neurovirulence and peripheral virulence in mice and non-human primates while eliciting robust neutralizing antibody responses and complete protection against lethal West Nile virus challenge. This strategy enables the development of live attenuated vaccines with modulated attenuation and stable safety profiles for West Nile virus.
Claims Coverage
The patent contains one independent claim covering an attenuated chimera virus and associated vaccine compositions. Three main inventive features constitute the claimed invention.
Attenuated West Nile virus and dengue type 4 virus chimera with structural protein substitution and 3′ UTR deletion
An attenuated chimera comprising a first nucleotide sequence encoding the West Nile virus premembrane/membrane (prM) and envelope (E) proteins and a second nucleotide sequence encoding the dengue virus type 4 capsid (C) protein and nonstructural proteins. The chimera genome further comprises a deletion of about 30 nucleotides in the 3′ untranslated region (nts10478-10507) corresponding to the TL2 stem-loop structure of dengue type 4 virus, which contributes to attenuation.
Specific amino acid motif at the cleavage site between dengue capsid protein and West Nile prM protein
The chimera contains a cleavage site junction between the dengue virus capsid protein and West Nile virus prM protein in which the West Nile prM protein includes an aspartic acid (Asp) residue at +3 amino acids downstream of the cleavage site and a threonine (Thr) residue at +6 amino acids downstream. This motif was found necessary for virus viability and infectivity.
Vaccine and immunogenic compositions containing the attenuation chimera
Pharmaceutical compositions comprising the attenuated West Nile virus and dengue type 4 chimera and a pharmaceutically acceptable carrier. These compositions are effective vaccines providing protection against West Nile virus challenge in animal models including mice and monkeys.
The claims cover live attenuated chimeric viruses constructed by substitution of West Nile structural protein genes into a dengue type 4 virus backbone with a defined 3′ UTR deletion and a specific cleavage site motif necessary for viability, and pharmaceutical compositions containing such chimeras as vaccines that protect against West Nile virus infection.
Stated Advantages
The chimeric viruses are significantly attenuated in neurovirulence and peripheral virulence compared to wild-type West Nile virus, increasing safety as vaccine candidates.
These chimeras retain strong immunogenicity, inducing robust neutralizing antibody responses and complete protection against lethal West Nile virus challenge in both mice and non-human primates.
The use of dengue virus backbones with characterized attenuating mutations, including the 3′ UTR Δ30 deletion, provides genetic stability and predictability of attenuation and safety.
The vaccine candidates can be produced by recombinant DNA techniques amenable to well-established cell culture production systems such as Vero cells.
Documented Applications
Use as live attenuated vaccines to prevent disease caused by West Nile virus in humans and domestic animals such as horses and birds.
Immunization of individuals at risk of West Nile virus infection, in particular prior to travel to endemic regions.
Use in pharmaceutical compositions, including immunogenic or vaccine formulations administered by various routes such as subcutaneous, intramuscular, oral, nasal, and others.
Development of diagnostic probes and primers for detection and differentiation of vaccine strain viruses in clinical or laboratory samples using nucleic acid hybridization or PCR-based assays.
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