Re: Natural infection with Japanese encephalitis virus among inhabitants of Japan: a nationwide survey of antibodies against nonstructural 1 protein.

Investigations to assess episodes of any natural Japanese encephalitis (JE) infection following prior immunizations with JE inactivated vaccine in Japan are commendable. Employing differential production of nonstructural 1 protein NS1, during a natural infection and not by inactivated JE vaccine [Konishi E, Shoda M, Yamamoto S, Arai S, Tanaka-Taya K, Okabe N. Natural infection with Japanese encephalitis virus among inhabitants of Japan: a nationwide survey of antibodies against nonstructural 1 protein. Vaccine 2006;24:3054-956], natural infection was manifest in eight selected prefectures in Japan. Moreover, it would be possible to detect any foreign pathogenic JE virus (JEV) or any native strains associated with any major shift in JE clinical presentations. On the opposite, any NS1 antibody screen might be invalid among recipients of live JE vaccines.