Objective:To investigate the infection status of Kaeng Khoi virus (KKV) in bat flies in Yunnan province.Methods:Specimens of the ectoparasitic bat flies on bats in Baoshan city in 2014 and Ruili city in 2017 were collected and identified, virus isolation was performed by cell culture. The positive isolates were amplified and sequenced to obtain the complete genome sequences, and homology comparison and phylogenetic analysis were carried out.Results:Three positive isolates (WDBC1704, WDBC1710 and BSBC1406) were identified from bat flies in Ruili city and Baoshan city. The supernatant was inoculated into BHK-21 cells for virus isolation, all of which could cause cytopathic effects (CPE) included shrinking, rounding and falling off of BHK-21 cells. The complete genome sequences of the three positive isolates were produced by RT-PCR and high-throughput sequencing. Phylogenetic analysis showed that the S, M, and L genes of all three positive isolates were in the same evolutionary branch as the original KKV strain PSC-19 isolated in Thailand. In this study, three KKV strains isolated were most closely related to the previous isolate WDBC1403 from Yunnan province, of which the BSBC1406 strain formed a small independent branch. The sequence comparison showed that there were significant differences in the M gene among the three isolates. The similarity between BSBC1406 and the other two strains (WDBC1704 and WDBC1710) was only 78.0%-78.1%, the amino acid similarity of the Gc protein in the open reading frame region was 85.3%.Conclusions:Three KKV strains from bat flies were quite different from the prototype strain, especially the BSBC1406 strain was somewhat different from other isolates and may have undergone variation. Surveillance of KKV carried by vector insects in Yunnan province and its relationship with human diseases should be strengthened.

Objective:To study the whole genome and genetic evolution characteristics of the Banna virus carried by Culicoides in Cangyuan County. Methods:Culicoides were collected in Cangyuan county in 2018. After grinding, the supernatant was inoculated onto BHK-21 cells for virus isolation. At the same time, the virus carrying status of Culicoides was detected by metatranscriptomics technology. Perl, Mafft and other bioinformatics softwares were used for sequence alignment, homology and molecular genetic evolution analysis. Results:Through metatranscriptomics method, the whole genome of Banna virus CYC1801 strain was obtained. Analysis of the whole genome showed that segment 4 and segment 7 are closely related to the Vietnamese strains, other segments are closely related to China strains. According to the phylogenetic analysis of the segment 12 gene, CYC1801 and the A2 gene subtype are in the same evolutionary branch and belong to the A2 gene subtype of Banna virus.Conclusions:Banna virus was carried by Culicoides collected in Cangyuan county, which may cause disease epidemic as a vector, so monitoring and prevention should be strengthened.