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Open Access Research article

Immune response to live-attenuated Japanese encephalitis vaccine (JE-CV) neutralizes Japanese encephalitis virus isolates from South-East Asia and India

Matthew Bonaparte1, Bashir Dweik1, Emmanuel Feroldi2, Claude Meric2, Alain Bouckenooghe3, Stephen Hildreth1, Branda Hu1, Sutee Yoksan4 and Mark Boaz1*

Author Affiliations

1 Sanofi Pasteur Global Clinical Immunology Department, Swiftwater, USA

2 Sanofi Pasteur Clinical Development Department, Marcy l’Etoile, France

3 Sanofi Pasteur Clinical Development, Singapore, Singapore

4 Center for Vaccine Development, Institute of Molecular Bioscience, Mahidol University, Bangkok, Thailand

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BMC Infectious Diseases 2014, 14:156  doi:10.1186/1471-2334-14-156

Published: 21 March 2014

Abstract

Background

During clinical development of the licensed Japanese encephalitis chimeric virus vaccine (JE-CV), the neutralization capacity of vaccine-induced antibodies was assessed against the vaccine virus and against well characterized wild-type (wt) viruses isolated between 1949–1991. We assessed whether JE-CV-induced antibodies can also neutralize more recent wt Japanese encephalitis virus (JEV) isolates including a genotype 1 isolate.

Methods

Sera from 12–18 month-old children who received a single dose of JE-CV in a phase III study in Thailand and the Philippines (ClinicalTrials.gov NCT00735644) were randomly selected and pooled according to neutralization titer against JE-CV into eight samples. Neutralization was assessed by plaque reduction neutralization tests (PRNT50) against three recent isolates from JEV genotypes 1 and 3 in addition to four JEV previously tested.

Results

Neutralization titers against the three recent JEV strains were comparable to those observed previously against other strains and the vaccine virus. The observed differences between responses to genotype 1 and 3 viruses were within assay variability for the PRNT50.

Conclusions

The results were consistent with previously generated data on the neutralization of wt JEV isolates, immune responses induced by JE-CV neutralize recently isolated virus from southeast (SE) Asia and India.

Keywords:
Japanese encephalitis vaccines; Humoral immune response; JEV; Wild-type strains