Key result
GIII-based Japanese encephalitis vaccines yield substantially lower neutralizing titers against reemerging Genotype V isolates.
Why the study?
The isolation of Japanese encephalitis virus genotype V in China in 2009 and the subsequent increase in JE cases in the Republic of Korea presented a new challenge.
Do genotype III-based Japanese encephalitis vaccines provide adequate neutralizing response against genotype V isolates in vaccinated individuals?
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.
Answers are grounded in this paper and cite their sources.
May indicate vulnerability to genotype V; leaves open need for updated vaccines in endemic regions.
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.
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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.
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