title: Investigation of the genotype III to genotype I shift in Japanese encephalitis virus and the impact on human cases.
abstract: Japanese encephalitis is a mosquito borne disease and is the leading cause of viral encephalitis in the Asia-Pacific area. The causative agent, Japanese encephalitis virus (JEV) can be phylogenetically classified into five genotypes based on nucleotide sequence. In recent years, genotype I (GI) has displaced genotype III (GIII) as the dominant lineage, but the mechanisms behind this displacement event requires elucidation. In an earlier study, we compared host variation over time between the two genotypes and observed that GI appears to have evolved to achieve more efficient infection in hosts in the replication cycle, with the tradeoff of reduced infectivity in secondary hosts such as humans. To further investigate this phenomenon, we collected JEV surveillance data on human cases and, together with sequence data, and generated genotype/case profiles from seven Asia-Pacific countries and regions to characterize the GI/GIII displacement event. We found that, when comprehensive and consistent vaccination and surveillance data was available, and the GIII to GI shift occurred within a well-defined time period, there was a statistically significant drop in JEV human cases. Our findings provide further support for the argument that GI is less effective in infecting humans, who represent a dead end host. However, experimental investigation is necessary to confirm this hypothesis. The study highlights the value of alternative approaches to investigation of epidemics, as well as the importance of effective data collection for disease surveillance and control.
authors: State Key Laboratory for Infectious Diseases Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206, China.
authors: Na
authors: N
authors: Han
authors: James
authors: J
authors: Adams
authors: Wei
authors: W
authors: Fang
authors: Si-Qing
authors: SQ
authors: Liu
authors: Simon
authors: S
authors: Rayner
mesh_terms: D000818:Animals; D001208:Asia; D004664:Encephalitis Virus, Japanese / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D004672:Encephalitis, Japanese / Q000453:epidemiology* / Q000635:transmission / Q000821:virology*; D062665:Epidemiological Monitoring; D005838:Genotype; D006801:Humans; D015994:Incidence; D017720:Molecular Epidemiology; D010139:Pacific Islands