Publication: Cross-protection elicited by primary and booster vaccinations against Japanese encephalitis: A two-year follow-up study
Issued Date
2013-12-17
Resource Type
ISSN
18732518
0264410X
0264410X
Other identifier(s)
2-s2.0-84891935899
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Mahidol University
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SCOPUS
Bibliographic Citation
Vaccine. Vol.32, No.1 (2013), 119-123
Suggested Citation
Elina O. Erra, Helena Hervius Askling, Sutee Yoksan, Lars Rombo, Jukka Riutta, Sirkka Vene, Lars Lindquist, Olli Vapalahti, Anu Kantele Cross-protection elicited by primary and booster vaccinations against Japanese encephalitis: A two-year follow-up study. Vaccine. Vol.32, No.1 (2013), 119-123. doi:10.1016/j.vaccine.2013.10.055 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/31138
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Title
Cross-protection elicited by primary and booster vaccinations against Japanese encephalitis: A two-year follow-up study
Abstract
Background: The inactivated Vero cell-derived vaccine (JE-VC, IXIARO) has replaced the traditional mouse brain-derived preparations (JE-MB) in travelers' vaccinations against Japanese encephalitis. We showed recently that a single JE-VC dose efficiently boosts immunity in JE-MB-primed vaccinees, and that JE-VC elicits cross-protective immunity against non-vaccine genotypes, including the emerging genotype I. While these studies only provided short-term data, the present investigation evaluates the longevity of seroprotection in the same volunteers. Methods: The study comprised 48 travelers who had received (1) JE-VC primary series, (2) JE-MB primary series followed by a single JE-VC booster dose, or (3) JE-MB primary series and a single JE-MB booster dose. Serum samples were collected two years after the last vaccine dose, and evaluated with the plaque-reduction neutralization test against seven Japanese encephalitis virus strains representing genotypes I-IV. PRNT50titers≥10 were considered protective. Results: Two years after the primary series with JE-VC, 87-93% of the vaccinees proved to be cross-protected against test strains representing genotypes II-IV and 73% against those of genotype I. After a single homologous or heterologous booster dose to JE-MB-primed subjects, the two-year seroprotection rates against genotype I-IV strains were 89-100%. Conclusions: After JE-VC primary series, seroprotection appeared to wane first against genotype I. The first booster should not be delayed beyond two years. In JE-MB-primed subjects, a single JE-VC booster provided cross-protective immunity against genotype I-IV strains in almost all vaccinees, suggesting an interval of two years or even longer for the second booster. These data further support the use of a single JE-VC dose for boosting JE-MB immunity. © 2013 The Authors.