title: Phase II, dose ranging study of the safety and immunogenicity of single dose West Nile vaccine in healthy adults ≥ 50 years of age.
abstract: BACKGROUND
  ChimeriVax-WN02 is a live, attenuated chimeric vaccine for protection against West Nile virus (WNV) produced by insertion of the genes encoding the pre-membrane (prM) and envelope (E) proteins of WNV (strain NY99) into the yellow fever 7D vaccine virus. This Phase II, randomized, double-blind, placebo-controlled, multi-center study in the US assessed the immunogenicity, viremia, and safety of the ChimeriVax-WN02 vaccine.
  
  
  METHODS
  The study included adults in general good health. Subjects aged ≥ 50 years were randomized to one of four treatment groups: ChimeriVax-WN02 4 × 10(3) plaque-forming units (pfu) (n=122), 4 × 10(4)pfu (n=124), 4 × 10(5)pfu (n=113), or placebo (n=120). A subset of subjects was randomized to assess viremia after vaccination at three different dose levels. Subjects were followed for safety up to 6 months after vaccination.
  
  
  RESULTS
  A total of 121 subjects for WN024 × 10(3), 122 for WN02 4 × 10(4), 110 for WN02 4 × 10(5), and 120 for the placebo group completed the study up to the 6-month safety follow-up. Seroconversion, as measured by plaque reduction neutralization test (PRNT), was achieved at Day 28 by 92.1%, 93.2%, and 95.4% of subjects in the WN02 4 × 10(3), the WN02 4 × 10(4), and the WN02 4 × 10(5) groups, respectively. Viremia was transient, detected between Days 2 and 14 but not at Day 28, and in most cases did not reach the quantification threshold. The percentage of subjects reporting at least one event of reactogenicity was similar in the placebo and active vaccine groups and showed no dose relationship.
  
  
  CONCLUSIONS
  The ChimeriVax-WN02 vaccine was highly immunogenic and well tolerated among subjects ≥ 50 years old at all dose levels.
authors.affiliation: Sanofi Pasteur, USA, 1 Discovery Drive, Swiftwater, PA 18370, USA. Gustavo.dayan@sanofipasteur.com
authors.forename: Gustavo H
authors.initials: GH
authors.lastname: Dayan
authors.forename: Joan
authors.initials: J
authors.lastname: Bevilacqua
authors.forename: Dorothy
authors.initials: D
authors.lastname: Coleman
authors.forename: Aileen
authors.initials: A
authors.lastname: Buldo
authors.forename: George
authors.initials: G
authors.lastname: Risi
mesh_terms: D000368:Aged; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D002522:Chlorocebus aethiops; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests; D014481:United States; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D014709:Vero Cells; D010948:Viral Plaque Assay; D014766:Viremia / Q000473:pathology; D053060:West Nile Virus Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology; D014902:West Nile virus / Q000276:immunology / Q000472:pathogenicity*; D015005:Yellow fever virus / Q000276:immunology
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; C445780:ChimeriVax; D014613:Vaccines, Attenuated; D053060:West Nile Virus Vaccines