Genotype III-based Japanese encephalitis vaccines elicited high neutralizing titers against GIII isolates but substantially lower geometric mean titers against reemerging Genotype V isolates.
Observational
Do genotype III-based Japanese encephalitis vaccines provide adequate neutralizing response against genotype V isolates in vaccinated individuals?
Current genotype III-based Japanese encephalitis vaccines elicit diminished neutralizing antibody responses against reemerging genotype V isolates, potentially leaving vaccinated individuals vulnerable.
BACKGROUND: Japanese encephalitis (JE) has been predominantly controlled through vaccination. However, the isolation of JE virus (JEV) genotype V (GV) in China in 2009, and the subsequent alarming increase in JE cases in the Republic of Korea since 2010, present a new challenge. METHODS: Serum samples from individuals vaccinated with genotype III (GIII)-based JE vaccines were analyzed for neutralizing seroresponse to GV isolates. RESULTS: Serum from immunocompromised pediatric patients vaccinated with an inactivated JE vaccine showed higher 50% plaque reduction neutralization test geometric mean titer (GMT) against GIII Nakayama (11 358; 95% confidence interval CI, 1790-29 658), but lower GMTs against GV isolates: GV Muar (499; 95% CI, 0-2437), GV 43279 (308; 95% CI, 159-582), and GV 43413 (231; 95% CI, 108-738). Similarly, 32 healthy volunteers receiving a live attenuated JE vaccine achieved 100% seroprotection against GIII Nakayama with GMT of 338 (95% CI, 304-651) at 1 month postvaccination. However, GMTs against GV isolates were 123 (95% CI, 102-446) for GV Muar, 81 (95% CI, 63-168) for GV 43279, and 107 (95% CI, 100-322) for GV 43413, not achieving 100% seroprotection against these isolates. At 6 months postvaccination, GMT against Nakayama increased to 696 (95% CI, 409-2353), while remaining similar for GV isolates. CONCLUSIONS: Our study underscores that current GIII-based vaccines do not provide comparable protection against GV JEVs, impacting individuals in both current and potential endemic regions, as well as travelers to these regions.
Lee et al. (2024) conducted an observational in Japanese encephalitis. Genotype III-based Japanese encephalitis vaccines was evaluated on Neutralizing seroresponse (50% plaque reduction neutralization test geometric mean titer) against GIII and GV isolates. Genotype III-based Japanese encephalitis vaccines elicited high neutralizing titers against GIII isolates but substantially lower geometric mean titers against reemerging Genotype V isolates.