Identification and genetic evolution of E gene of a duck Tambusu virus isolated from southeast Guizhou Province

Abstract

Abstract Since 2010, several strains of Duck Tembusu Virus (DTMUV) have been isolated from China. In autumn 2021, high mortality was observed in southwestern Guizhou Province, China, and a DTMUV strain named GZSS2022 was successfully isolated. After inoculation with SPF chicken embryos of 10 days age, the embryos died 3-5 days after inoculation, and RT-PCR could still detect DTMUV positive after collecting the allantoic fluid of dead chicken embryos and transmitting it for 4 generations. In addition, the GZSS2022 strain was able to replicate in BHK-21 cells and induce cytopathic effects (CPE), and the virus particles were observed in the cytoplasm by transmission electron microscopy. In animal experiments, GZSS2022 strain can replicate stably and pathological examination results showed that the brain of infected ducks was congested and vascular sheath formed around the blood vessels; Liver lymphocyte infiltration, necrosis, liver bleeding. The E gene of this strain was sequenced by PCR and its homology and genetic evolution were analyzed. It was found that the homology of GZSS2022 with the Beijing duck reference strain (MT108699.1) was the highest 99.39%, and the homology of GZSS2022 with the early isolated reference strain (FX2010) was 96.88%. The GZSS2020 strain was located in the same subbranch as the reference strain from Beijing duck in China. The results of this study indicate that a novel highly virulent Tambusu virus has appeared for the first time in Guizhou Province, China, and further lay the foundation for the study of the pathogenicity and host range of this novel Tambusu virus.