New mechanism of Japanese encephalitis virus host adaptation revealed

Reporters : Li Chen, Wang Lei / Publisher : China Science News / Direct translation

Ref : http://news.sciencenet.cn/htmlnews/2020/9/445532.shtm

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From the 1930s to the end of the 20th century, genotype III (GIII) strains have always occupied the main position of Japanese encephalitis virus epidemic in Asia. However, in the past 20 years, genotype I (GI) has gradually replaced GIII as the main epidemic strain in the entire Asian region, and the molecular mechanism of genotype conversion is currently unclear.

On September 3, the U.S. "Public Library of Science-Virology" published online the latest results of Ma Zhiyong's team, a researcher at the Shanghai Institute of Veterinary Medicine, Chinese Academy of Agricultural Sciences. The team found that the GI type has an adaptive advantage over the GIII type in waterfowl hosts. This advantage has host specificity and is only found in avian hosts. This provides a new idea for exploring the reasons why the Japanese encephalitis virus has changed from GIII to GI in my country and even the entire Asian region in recent years.

Japanese encephalitis virus belongs to the flavivirus genus of the Flaviviridae family. It can cause diseases such as human central nervous system damage and pig reproductive disorders. In nature, it is mainly transmitted through mosquito bites. Mosquitoes are the transmission host of the virus, and waterfowl and pigs are The main amplification host of the virus.

The team's research found that GI type has an adaptive advantage in waterfowl hosts over GIII, and can cause ducklings to produce viremia with higher titer and longer duration. The differences in host adaptability are thought to be an important cause of Japanese encephalitis virus genotype conversion.

They also revealed that the GI virus has a stronger ability to antagonize type I interferons in waterfowl hosts, thereby enhancing its adaptability. Compared with the GIII type, the GI virus can specifically induce lower levels of IFN-α and β expression in the waterfowl host, thus showing the advantage of adaptability to the waterfowl host.

Related paper information: https://doi.org/10.1371/journal.ppat.1008773