Isolation and full-genome sequences of Japanese encephalitis virus genotype I strains from Cambodian human patients, mosquitoes and pigs : J Gen Virol, 2017Sep05
Duong V, Choeung R, Gorman C, Laurent D, Crabol Y, Mey C, Peng B, Di Francesco J, Hul V, Sothy H, Santy K, Richner B, Pommier JD, Sorn S, Chevalier V, Buchy P, de Lamballerie X, Cappelle J, Horwood PF, Dussart P.
J Gen Virol. 2017 Aug 18. DOI: 10.1099/jgv.0.000892
“Japanese encephalitis remains the most important cause of viral encephalitis in humans in several Southeast Asian countries, including Cambodia, causing at least 65 000 cases of encephalitis per year. This vector-borne viral zoonosis – caused by Japanese encephalitis virus (JEV) – is considered to be a rural disease and is transmitted by Culex mosquitoes, with birds and pigs being the natural reservoirs, while humans are accidental hosts. Although less than 1% of humans infected with JEV will develop encephalitis, approximately 25–30% of cases attracting medical attention are fatal, and 50% of survivors will develop severe neurological sequelae. JE is recognized as the most prevalent cause of encephalitis and febrile illness in Cambodia, particularly in children and adolescents. In a study conducted by Institut Pasteur in Cambodia in collaboration with Kunthabopha hospitals, among 1160 paediatric acute meningo-encephalitis cases, JEV was the most commonly identified pathogen (n=283, 24.4 %).
In this study we report the first two JEV isolates in Cambodia from human encephalitis cases from two studies on the aetiology of central nervous system disease, conducted at the two major paediatric hospitals in the country. We also report JEV isolates from Culex tritaeniorhynchus mosquitoes and from pig samples collected in two farms, located in peri-urban and rural areas. Out of 11 PCR positive samples, we generated 5 full-genome sequences, 5 partial sequences of the JEV NS3 gene and one complete coding sequence of the envelope gene. Phylogenetic analyses revealed that JEV detected in Cambodia belonged to genotype I and clustered in two clades: genotype I-a, mainly comprising strains from Thailand, and genotype I-b, comprising strains from Vietnam that dispersed northwards to China. Finally, in this study, we provide proof that the sequenced JEV strains circulate between pigs, Culex tritaeniorhynchus and humans in the Phnom Penh vicinity and useful information for JEV vaccination program which has recently been launched in Cambodia.”