title: Immunogenicity of an inactivated Japanese encephalitis vaccine (JE-VAX) in humans over 20 years at USAMRIID: using PRNT50 as an endpoint for immunogenicity.
abstract: Two hundred and ninety-three subjects received a three-dose primary JE-VAX series and had post-primary shot 3 titers within 56 days at USAMRIID from 1985 to 2005. Overall, the PRNT50 primary response rate (titer of 1:10 or greater) was 269/293 (92%). Eighteen out of 19 subjects (95%) responded with adequate PRNT50 titer within 56 days after first JE-VAX boost. Primary PRNT50 responses to JE-VAX varied significantly in response rates and in geometric means (GMT) by vaccine lot. We recommend that future vaccine studies using PRNT as an immunologic endpoint include a coefficient of variation result alongside the GMT to assist in evaluating GMT results. For subjects who responded within 56 days of primary shot 3, 50% experienced a PRNT50 decline in titer to <1:10 at 805 days and a PRNT80 decline in titer to <1:10 at 355 days. Consequently, for individuals traveling to JE endemic areas, we recommend JE-VAX boost every 2 years and for individuals working with high titers of JE virus in the lab setting, we would recommend JE-VAX boost annually.
authors.affiliation: United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, MD 21702-5011, United States. Ronald.Reisler@amedd.army.mil <Ronald.Reisler@amedd.army.mil>
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Reisler
authors.forename: Denise K
authors.initials: DK
authors.lastname: Danner
authors.forename: Paul H
authors.initials: PH
authors.lastname: Gibbs
mesh_terms: D000328:Adult; D057134:Antibodies, Neutralizing / Q000097:blood*; D000914:Antibodies, Viral / Q000097:blood*; D004672:Encephalitis, Japanese / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007117:Immunization, Secondary; D022321:Japanese Encephalitis Vaccines / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests / Q000379:methods; D013997:Time Factors; D015164:Vaccines, Inactivated / Q000276:immunology; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D022321:Japanese Encephalitis Vaccines; D015164:Vaccines, Inactivated