Molecular epidemiological analyses of Japanese encephalitis virus isolates from swine in Japan from 2002 to 2004.
To characterize Japanese encephalitis virus (JEV) strains recently prevalent in Japan, JEV surveillance was performed in pigs from 2002 to 2004. Eleven new JEV isolates were obtained and compared with previous isolates from Japan and other Asian countries. All of the isolates were classified into genotype 1 by nucleotide sequence analysis of the E gene. Two new isolates with different levels of neurovirulence and neuroinvasiveness, but with only one nucleotide difference in the E gene, Sw/Mie/34/2004 and Sw/Mie/40/2004, were isolated at the same farm on the same day. Sw/Mie/40/2004 displayed higher neurovirulence and neuroinvasiveness in mice than the other four new isolates. Another new isolate, Sw/Hiroshima/25/2002, was neutralized by antiserum to Beijing-1 at a level similar to the homologous Beijing-1 strain, whilst seven other new isolates were neutralized at 10-fold-lower titres. However, there were no amino acid differences in the E protein among these eight isolates. The present study indicated that the 11 new JEV isolates were genetically similar, but biologically and serologically heterogeneous.
Nerome
Reiko
R
Department of Virology 1, National Institute of Infectious Diseases (NIID), Toyama, Shinjuku, Tokyo 162-8640, Japan.
Tajima
Shigeru
S
Department of Virology 1, National Institute of Infectious Diseases (NIID), Toyama, Shinjuku, Tokyo 162-8640, Japan.
Takasaki
Tomohiko
T
Department of Virology 1, National Institute of Infectious Diseases (NIID), Toyama, Shinjuku, Tokyo 162-8640, Japan.
Yoshida
Takashi
T
Mitsubishi Kagaku Bio-Clinical Laboratories Inc., Tokyo, Japan.|Department of Virology 1, National Institute of Infectious Diseases (NIID), Toyama, Shinjuku, Tokyo 162-8640, Japan.
Kotaki
Akira
A
Department of Virology 1, National Institute of Infectious Diseases (NIID), Toyama, Shinjuku, Tokyo 162-8640, Japan.
Lim
Chang-Kweng
CK
Department of Virology 1, National Institute of Infectious Diseases (NIID), Toyama, Shinjuku, Tokyo 162-8640, Japan.
Ito
Mikako
M
Department of Virology 1, National Institute of Infectious Diseases (NIID), Toyama, Shinjuku, Tokyo 162-8640, Japan.
Sugiyama
Akira
A
Mie Prefectural Institute of Public Health and Environmental Sciences, Mie, Japan.
Yamauchi
Akinori
A
Mie Prefectural Institute of Public Health and Environmental Sciences, Mie, Japan.
Yano
Takuya
T
Mie Prefectural Institute of Public Health and Environmental Sciences, Mie, Japan.
Kameyama
Taeko
T
Kagawa Prefectural Institute of Environment and Health, Kagawa, Japan.
Morishita
Ichiko
I
Kagawa Prefectural Institute of Environment and Health, Kagawa, Japan.
Kuwayama
Masaru
M
Hiroshima Prefectural Institute of Health and Environment, Hiroshima, Japan.
Ogawa
Tomoko
T
Chiba Prefectural Institute of Public Health, Chiba, Japan.
Sahara
Keiji
K
Shizuoka Prefectural Institute of Environment and Hygiene, Shizuoka, Japan.
Ikegaya
Asaka
A
Shizuoka Prefectural Seibu Meat Inspection Center, Shizuoka, Japan.
Kanda
Masahiro
M
Shizuoka Prefectural Seibu Meat Inspection Center, Shizuoka, Japan.
Hosoya
Yoshiyuki
Y
Shizuoka Prefectural Seibu Meat Inspection Center, Shizuoka, Japan.
Itokazu
Kiyomasa
K
Okinawa Prefectural Institute of Health and Environment, Okinawa, Japan.
Onishi
Hajime
H
Ishikawa Prefectural Institute of Public Health and Environmental Science, Ishikawa, Japan.
Chiya
Seizou
S
The Public Health Institute of Kochi Prefecture, Kochi, Japan.
Yoshida
Yasuko
Y
Tokyo Metropolitan Institute of Public Health, Tokyo, Japan.
Tabei
Yukiko
Y
Tokyo Metropolitan Institute of Public Health, Tokyo, Japan.
Katsuki
Kazuko
K
Kumamoto Prefectural Institute of Public Health and Environmental Science, Kumamoto, Japan.
Tabata
Koji
K
Kumamoto Prefectural Institute of Public Health and Environmental Science, Kumamoto, Japan.
Harada
Seiya
S
Kumamoto Prefectural Institute of Public Health and Environmental Science, Kumamoto, Japan.
Kurane
Ichiro
I
Department of Virology 1, National Institute of Infectious Diseases (NIID), Toyama, Shinjuku, Tokyo 162-8640, Japan.
D000818:Animals; D001181:Arthropods / Q000821:virology; D001208:Asia / Q000453:epidemiology; D004664:Encephalitis Virus, Japanese / Q000235:genetics* / Q000302:isolation & purification* / Q000472:pathogenicity; D004672:Encephalitis, Japanese / Q000453:epidemiology* / Q000635:transmission / Q000662:veterinary*; D007564:Japan / Q000453:epidemiology; D008969:Molecular Sequence Data; D013552:Swine / Q000821:virology*; D013553:Swine Diseases / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D014774:Virulence