Molecular Epidemiology of Japanese Encephalitis Virus in Okinawa

Abstract

In order to elucidate the molecular characteristics of Japanese encephalitis (JE) virus in Okinawa, 23 strains of JE virus isolated in a 25-year span were sequenced for the 240 nucleotides of the C-preM junction region and 111 nucleotides of the E gene region and compared with those of reference strains isolated in mainland Japan. The results of phylogenic analysis showed that although all the Okinawan isolates showed more than 96% homology in the nucleotide sequence in each region, they were chronologically divided into two groups: the old group (nine strains) and a new group (14 strains). On the other hand, in a comparison with reference strains in mainland Japan, the Okinawan isolates showed more than 94% nucleotide sequence homology in both regions, indicating that the Okinawan strains belong to the same genotype as that of JE strains in mainland Japan. The nucleotide homology of the old group was relatively higher than that of the new group. Among the 14 strains in the new group, 13 strains were isolated from mosquitoes collected from a pig farm from 1986 through 1992. These strains showed higher nucleotide divergence than the old group strains, isolated from mosquitoes and swine sera collected at several sites, in both regions. A nucleotide substitution at the position 1920 in the E gene was identified in three isolates. This substitution generated an asparagine-proline-threonine sequence capable of serving as an attachment site of carbohydrate.

Recent Change of the Antigenicity and Genotype of Japanese Encephalitis Viruses Distributed on Okinawa Island, Japan

“…[18][19][20][21][22][23] More than 150 strains of JEV have been isolated on Okinawa Island and all of the 23 sequenced isolates collected between 1968 and 1992 belonged to genotype 3. 24 Okinawan strains collected between 1986 and 1991 exhibited a different antigenic profile from the Nakayama and JaGAr#01 strains. 22 We conducted a genetic and sero-epidemiologic study of JEV to clarify the recent changes of its distribution on Okinawa Island.…”

Shift in Japanese encephalitis virus (JEV) genotype circulating in northern Vietnam: implications for frequent introductions of JEV from Southeast Asia to East Asia

“…Japan and Korea have recently reported the introduction of JEV G1 (Takegami et al, 2000;Nam et al, 1996;Ma et al, 2003). Ma et al (1996) reported that JEV strains in Japan isolated from 1968 to 1992 belong to G3. Most recently, Ma et al (2003) stated that Japanese JEV strains, mostly from swine serum, isolated between 1965 and 1991 clustered within G3, but all strains isolated from 1994 to 2001 clustered within G1.…”

Short Report: A Major Genotype of Japanese Encephalitis Virus Currently Circulating in Japan

“…1 The geographic variation of JEV strains was demonstrated by the studies of RNA finger-prints 2,3 and nucleotide sequencing. [4][5][6][7][8][9][10] The genomic diversity of JEV has been determined by primer extension sequencing of the capsid/pre-membrane (C/prM) gene region. 4,5 These analyses indicated that JEV strains could be classified into four geographically distinct genotypes based on the nucleotide differences of more than 12%.…”

“…The RNA of JEV-infected C6/36 cells was amplified by a reverse transcriptase−polymerase chain reaction with a pair of primers (JE317 and JE821R), 14 followed by sequencing as previously described. 8 Phylogenetic analyses were then performed on sequence information for a 240-nucleotide region of the C/prM gene. 4,5 A FIGURE 2.…”