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Emergence of Japanese encephalitis virus genotype V in the Republic of Korea.

ABSTRACT: BACKGROUND: Japanese encephalitis virus (JEV) genotype V reemerged in Asia (China) in 2009 after a 57-year hiatus from the continent, thereby emphasizing a need to increase regional surveillance efforts. Genotypic characterization was performed on 19 JEV-positive mosquito pools (18 pools of Culex tritaeniorhynchus and 1 pool of Cx. bitaeniorhynchus) from a total of 64 positive pools collected from geographically different locations throughout the Republic of Korea (ROK) during 2008 and 2010. FINDINGS: Two regions of the JEV genome were sequenced from 19 pools; the envelope gene and the nonstructural protein 5 (NS5)/3'-untranslated region (UTR). Eighteen pools of Culex tritaeniorhynchus and one pool of Cx. bitaeniorhynchus were positive for genotype I and genotype V, respectively. Sequence alignment of the complete E gene from Cx. bitaeniorhynchus showed high amino acid similarity (98.8%) to the Muar strain, characterized as the first report of genotype V, isolated from an encephalitis patient in Malaysia in 1952. CONCLUSION: This study represents the first report of JEV genotype V in the ROK. The reemergence of genotype V in Asia (China and ROK) after more than a half-century and its discovery in Cx. bitaeniorhynchus, a mosquito species previously unknown to carry JEV in the ROK, emphasizes the need for enhanced JE surveillance to monitor the dynamics of JEV strains within the region. Future findings may have implications with regard to JEV vaccination/prevention strategies.

SUBMITTER: Takhampunya R

PROVIDER: S-EPMC3196923 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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Emergence of Japanese encephalitis virus genotype V in the Republic of Korea.

Takhampunya Ratree R Kim Heung-Chul HC Tippayachai Bousaraporn B Kengluecha Ampornpan A Klein Terry A TA Lee Won-Ja WJ Grieco John J Evans Brian P BP

Virology journal 20110923

<h4>Background</h4>Japanese encephalitis virus (JEV) genotype V reemerged in Asia (China) in 2009 after a 57-year hiatus from the continent, thereby emphasizing a need to increase regional surveillance efforts. Genotypic characterization was performed on 19 JEV-positive mosquito pools (18 pools of Culex tritaeniorhynchus and 1 pool of Cx. bitaeniorhynchus) from a total of 64 positive pools collected from geographically different locations throughout the Republic of Korea (ROK) during 2008 and 20 ...[more]

PMID: 21943222

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Project description:UnlabelledIn recent years, genotype I (GI) of Japanese encephalitis virus (JEV) has displaced genotype III (GIII) as the dominant virus genotype throughout Asia. In this study, the largest collection of GIII and GI envelope gene-derived viral sequences assembled to date was used to reconstruct the spatiotemporal chronology of genotype displacement throughout Asia and to determine the evolutionary and epidemiological dynamics underlying this significant event. GI consists of two clades, GI-a and GI-b, with the latter being associated with displacement of GIII as the dominant JEV genotype throughout Asia in the 1990s. Phylogeographic analysis indicated that GI-a diverged in Thailand or Cambodia and has remained confined to tropical Asia, whereas GI-b diverged in Vietnam and then dispersed northwards to China, where it was subsequently dispersed to Japan, Korea, and Taiwan. Molecular adaptation was detected by more than one method at one site (residue 15), and coevolution was detected at two pairs of sites (residues 89 to 360 and 129 to 141) within the GI E gene protein alignment. Viral multiplication and temperature sensitivity analyses in avian and mosquito cells revealed that the GI-b isolate JE-91 had significantly higher infectivity titers in mosquito cells from 24 to 48 h postinfection than did the GI-a and GIII isolates. If the JE-91 isolate is indeed representative of GI-b, an increased multiplicative ability of GI-b viruses compared to that of GIII viruses early in mosquito infection may have resulted in a shortened extrinsic incubation period that led to an increased number of GI enzootic transmission cycles and the subsequent displacement of GIII.ImportanceJapanese encephalitis virus (JEV), a mosquito-borne flavivirus, represents the most significant etiology of childhood viral neurological infection in Asia. Despite the existence of effective vaccines, JEV is responsible for an estimated 68,000 human cases and a reported 10,000 to 15,000 deaths annually. Phylogenetic studies divided JEV into five geographically and epidemiologically distinct genotypes (GI to GV). GIII has been the source of numerous JEV epidemics throughout history and was the most frequently isolated genotype throughout most of Asia from 1935 until the 1990s. In recent years, GI has displaced GIII as the most frequently isolated virus genotype. To date, the mechanism of this genotype replacement has remained unknown. In this study, we have identified genetic determinants underlying the genotype displacement as it unfolded across Asia. JEV provides a paradigm for other flaviviruses, including West Nile, yellow fever, and dengue viruses, and the critical role of the selective advantages in the mosquito vector.

Dataset Information

Emergence of Japanese encephalitis virus genotype V in the Republic of Korea.

Publications

Emergence of Japanese encephalitis virus genotype V in the Republic of Korea.

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