Persistence of Wild-Type Japanese Encephalitis Virus Strains Cross-Neutralization 5 Years After JE-CV Immunization

• Published in: The Journal of infectious diseases Vol. 215; no. 2; pp. 221 - 227
• Main Authors: Feroldi, Emmanuel, Boaz, Mark, Yoksan, Sutee, Chokephaibulkit, Kulkanya, Thisyakorn, Usa, Pancharoen, Chitsanu, Monfredo, Céline, Bouckenooghe, Alain
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 15.01.2017
• Subjects: Animals; Antibodies, Neutralizing - blood; Antibodies, Viral - blood; Asia, Southeastern; Child, Preschool; Cross Reactions; Encephalitis Virus, Japanese - immunology; Female; Humans; India; Japanese Encephalitis Vaccines - administration & dosage; Japanese Encephalitis Vaccines - immunology; Major and Brief Reports; Male; Time Factors; VIRUSES; genotypes; long-term protection; cross-neutralization; wild-type strains; Japanese encephalitis vaccines
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1093/infdis/jiw533

Background. The live-attenuated Japanese encephalitis (JE) vaccine (JE-CV; IMOJEV) induces a protective response in children. A shift in circulating JE virus strains suggests that a genotype shift phenomenon may occur throughout Southeast Asia. We assessed the neutralization of wild-type (WT) JE virus isolates at distal time points after vaccination. Methods. We analyzed serum samples from a subset of 47 children who had received a JE-CV booster after an inactivated JE vaccine primary immunization. We measured antibody titers (50% plaque reduction neutralization test) using a panel of WT JE strains at baseline, then after the booster at 28 days and 6 months in all subjects present at the time points and in a subset at year 5. Three additional recent isolates were tested at year 5. Results. Of 47 subjects, 43 (91.5%) subjects had JE neutralizing antibody titers ≥10 (reciprocal serum dilution) against the homologous strain before JE-CV boost; all were seroprotected up to year 5 after the JE-CV boost. Baseline WT seroprotection ranged between 78.7% and 87.2%; all subjects were seroprotected against the 4 WT strains at 28 days and 6 months; year 5 seroprotection ranged between 95.7% and 97.9%. Similar rates of protection against 3 additional WT isolates were observed at year 5. Conclusions. The long-term immune responses induced after a JE-CV booster dose in toddlers were able to neutralize WT viruses from various genotypes circulating in Southeast Asia and India. Clinical Trials Registration. NCT00621764.