title: Directed molecular evolution improves the immunogenicity and protective efficacy of a Venezuelan equine encephalitis virus DNA vaccine.
abstract: We employed directed molecular evolution to improve the cross-reactivity and immunogenicity of the Venezuelan equine encephalitis virus (VEEV) envelope glycoproteins. The DNA encoding the E1 and E2 proteins from VEEV subtypes IA/B and IE, Mucambo virus (MUCV), and eastern and western equine encephalitis viruses (EEEV and WEEV) were recombined in vitro to create libraries of chimeric genes expressing variant envelope proteins. ELISAs specific for all five parent viruses were used in high-throughput screening to identify those recombinant DNAs that demonstrated cross-reactivity to VEEV, MUCV, EEEV, and WEEV after administration as plasmid vaccines in mice. Selected variants were then used to vaccinate larger cohorts of mice and their sera were assayed by both ELISA and by plaque reduction neutralization test (PRNT). Representative variants from a library in which the E1 gene from VEEV IA/B was held constant and only the E2 genes of the five parent viruses were recombined elicited significantly increased neutralizing antibody titers to VEEV IA/B compared to the parent DNA vaccine and provided improved protection against aerosol VEEV IA/B challenge. Our results indicate that it is possible to improve the immunogenicity and protective efficacy of alphavirus DNA vaccines using directed molecular evolution.
authors.affiliation: Virology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA.
authors.forename: Lesley C
authors.initials: LC
authors.lastname: Dupuy
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Locher
authors.forename: Madan
authors.initials: M
authors.lastname: Paidhungat
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Richards
authors.forename: Cathleen M
authors.initials: CM
authors.lastname: Lind
authors.forename: Russell
authors.initials: R
authors.lastname: Bakken
authors.forename: Michael D
authors.initials: MD
authors.lastname: Parker
authors.forename: Robert G
authors.initials: RG
authors.lastname: Whalen
authors.forename: Connie S
authors.initials: CS
authors.lastname: Schmaljohn
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D003429:Cross Reactions; D019020:Directed Molecular Evolution; D004666:Encephalitis Virus, Venezuelan Equine / Q000235:genetics / Q000276:immunology*; D004685:Encephalomyelitis, Venezuelan Equine / Q000517:prevention & control*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D016019:Survival Analysis; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology; D010948:Viral Plaque Assay
chemical_list: D000914:Antibodies, Viral; D019444:Vaccines, DNA; D014759:Viral Envelope Proteins