Open AccessContinuity and Change of Japanese Encephalitis Virus in Toyama Prefecture, Japan
Author(s) -
Mayumi Obara,
Takeo Yamauchi,
Mamoru Watanabe,
Sumiyo Hasegawa,
Yasufumi Ueda,
Kentaro Matsuno,
Masae Iwai,
Eiji Horimoto,
Takeshi Kurata,
Takenori Takizawa,
Hiroaki Kariwa,
Ikuo Takashima
Publication year - 2011
Publication title -
the american journal of tropical medicine and hygiene
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.015
H-Index - 151
eISSN - 1476-1645
pISSN - 0002-9637
DOI - 10.4269/ajtmh.2011.10-0188
Subject(s) - japanese encephalitis , culex tritaeniorhynchus , virology , biology , capsid , virus , genotype , outbreak , phylogenetics , phylogenetic tree , gene , encephalitis , veterinary medicine , genetics , medicine
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 Culex tritaeniorhynchus 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 Cx. tritaeniorhynchus. 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.