Volume 84, Issue 5
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



To determine the mechanisms of maintenance and evolution of Japanese encephalitis virus (JEV) in a temperate zone, we attempted to isolate JEV from mosquitoes and pigs in Toyama Prefecture, Japan. A total of 87 JEVs were isolated from female mosquitoes and pigs during 2005–2009. The prevalence of JEV in Toyama Prefecture was seasonally late in comparison with that of the virus during 1966–1972. Furthermore, JEVs were isolated after the peak in the number of female . Among JEV strains isolated in this study, two distinct groups were observed within genotype I of the phylogeny generated from nucleotide sequence information derived from the envelope and capsid/premembrane genes: strains belonging to the major type were isolated during 2005–2009, and strains from the minor type were isolated only in 2007. The major type has exhibited gradual change in its envelope and capsid/premembrane genes, and all isolates obtained in 2008 and 2009 had a novel deletion of seven nucleotides in the variable region of the 3′-untranslated region.


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  • Received : 29 Mar 2010
  • Accepted : 04 Feb 2011

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