State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
Guangxi Key Laboratory of Veterinary Biotechnology, Guangxi Veterinary Research Institute, Nanning, China.
Transbound Emerg Dis. 2022 Sep;69(5):e2164-e2174. doi: 10.1111/tbed.14555. Epub 2022 Apr 22.
Bluetongue virus (BTV), a member of the genus Orbivirus in the family Reoviridae, is transmitted by biting midges and causes severe disease in domestic and wild ruminants. In the present study, a BTV strain, BTV-20/GX015/China/2013 (GX015), was isolated from sentinel cattle in Guangxi, China. Virus neutralization tests and phylogenetic analyses based on genomic segments 2 (S2) and 6 (S6) indicated that GX015 belongs to BTV serotype 20 (BTV-20) and represents a new topotype within BTV-20 strains, which makes GX015 the first BTV-20 strain isolated in China. Genomic analyses suggested that the 10 genomic segments of GX015 originated from a reassortment event, in which S2 and S6 are derived from exotic BTV-20 strains (South Africa or Australia), whereas the remaining eight genomic segments are apparently of Chinese origin and most likely share the same ancestor with a Taiwanese BTV-12 strain. Importantly, we evaluated the infectivity and pathogenicity of the BTV-20 strain in mice lacking the interferon receptor (IFNAR mice, a good animal model for studying the pathogenesis, virulence and transmission of BTVs) and sheep for the first time, and found that GX015 causes severe disease and death in IFNAR mice and clinical signs and viraemia in the natural host sheep. These results improve our understanding of the genetic characteristics, diversity and pathogenicity of BTVs, which is important for developing diagnostic methods and vaccines for the surveillance and prevention of bluetongue disease.
蓝舌病病毒（BTV）是呼肠孤病毒科环状病毒属的成员，由吸血蠓传播，可引起家畜和野生动物严重疾病。本研究从中国广西的哨兵牛中分离到一株 BTV 株，BTV-20/GX015/China/2013（GX015）。基于基因组片段 2（S2）和 6（S6）的病毒中和试验和系统发育分析表明，GX015 属于 BTV 血清型 20（BTV-20），代表 BTV-20 株的一个新拓扑型，这使得 GX015 成为中国分离的第一株 BTV-20 株。基因组分析表明，GX015 的 10 个基因组片段来源于重组事件，其中 S2 和 S6 来源于外来 BTV-20 株（南非或澳大利亚），而其余 8 个基因组片段显然来自中国，很可能与一株中国台湾 BTV-12 株具有共同祖先。重要的是，我们首次在缺乏干扰素受体的小鼠（IFNAR 小鼠，研究 BTV 发病机制、毒力和传播的良好动物模型）和绵羊中评估了 BTV-20 株的感染性和致病性，发现 GX015 可引起 IFNAR 小鼠严重疾病和死亡，以及天然宿主绵羊的临床症状和病毒血症。这些结果提高了我们对 BTV 的遗传特征、多样性和致病性的认识，对于开发诊断方法和疫苗以监测和预防蓝舌病具有重要意义。
