云南省蓝舌病病毒血清7型毒株的分离与基因组序列分析

2014年,我国广东省的哨兵牛上分离出蓝舌病病毒血清7型(B T V-7)毒株,但该血清型病毒在我国的流行情况尚不清楚,本研究旨在分离我国流行的BT V-7型毒株并掌握其遗传特征.作者在云南省景洪市勐罕镇设立哨兵牛,每周定时采血,并接种C6/36、B H K-21细胞分离虫媒病毒,通过病毒蚀斑试验与增殖曲线分析病毒在细...

Whole Genome Sequence Analyses of Bluetongue Virus Serotype 7 Strain Isolated from Yunnan Province

Bluetongue virus serotype 7 (BTV-7) was firstly isolated from sentinel cattle in Guangdong Province in 2014; however, the epidemic situation of this serotype was still not clear in China. The objective of the present study is to isolate and analyze the genomic characterization of BTV-7 epideictic in China. Sentinel cattle were placed in Jinghong County, Yunnan Province, and blood samples were collected weekly for arbovirus isolation by inoculating cells. Complete genome sequence of the isolated virus was obtained by high-throughput sequencing. The infection feature of the isolated virus on cells were analyzed by virus plaque assay and proliferation curve analysis. The dynamics of viral nucleic acids and antibodies in the blood of infected sentinel cattle were monitored by serum neutralization test (SNT) and qRT-PCR. In May 2020, a virus strain (V303/YNJH/2020) causing cytopathic effects (CPE) on BHK-21 cells was isolated from the blood sample collected from sentinel cattle, which was serotyped as BTV-7. The genome of V303/YNJH/2020 was 19 154 bp in length (GenBank accession numbers: MW046280 to MW046289), which showed the closest relationship to the BTV-7 GDST008 strain isolated in Guangdong Province in 2014, with nucleic acid (nt) and encoding protein amino acid (aa) sequence identities of segment 1 to 6, segment 9 and 10 higher than 98% and 99%. However, the segment 7 and 8 of V303/YNJH/2020 belonged to the Western topotype, shared nt/aa sequence identities of 71.5%/81.6% and 79.6%/84.4% with the corresponding segment of GSDT008. Results of virus plaque assay and proliferation curve analysis showed that the proliferation ability of V303/YNJH/2020 in BHK-21 cells was significantly robust than that of GDST008. Sentinel cattle infected with V303/YNJH/2020 did not show observed clinical symptoms, but viral nucleic acids in the blood persisted up to 12 weeks, and neutralization antibodies in blood remained at titers of 1:256 during 4-9 weeks after virus infection. The BTV-7 strain V303/YNJH/2020 isolated in Yunnan Province in 2020 has the closest relationship with BTV-7 strain of GDST008, and possessed robust proliferation ability on cells than GDST008. The infection of V303/YNJH/2020 did not cause clinical symptoms in cattle, but viral nucleic acids and neutralization antibodies existed in the blood of infected cattle for a long time. The results of this study laid the foundation for the research on evolution, viral mutation caused by reassortment and pathogenicity of BTV-7 strains.