Chen Wanting, Tu Teng, Luo Yan, Yang Zexiao, Yao Xueping, Wu Xulong, Wang Yin
College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China.
J Vet Res. 2022 Sep 14;66(3):289-295. doi: 10.2478/jvetres-2022-0048. eCollection 2022 Sep.
In May 2020, an outbreak of rabbit haemorrhagic disease 2 (RHD2) caused by the rabbit haemorrhagic disease virus 2 (RHDV2, GI.2) occurred in Sichuan, China. The acute onset and short disease course resulted in rabbit mortality as high as 42.86%. Currently, basic research on the aetiology and genetic characteristics of GI.2 is lacking in China.
Pathological changes in various tissues from infected rabbits were investigated and the viral genome was characterised. This study used RT-PCR, histopathology and scanning electron microscopy to identify the pathogen in samples from infected rabbits that had died. Phylogenetic trees were constructed based on whole genome sequence analysis, and recombination events were analysed.
RT-PCR identified the presence of GI.2. Histopathology revealed liver cell necrosis and haemorrhaging into lung alveoli. Electron microscopy demonstrated spherical GI.2 particles that were 40 nm in size. The gene sequence length of the isolate was 7,445 bp (GenBank accession number MW178244). A phylogenetic analysis based on the genome of the isolated strain and 60 reference strains showed that the isolate was grouped together with GI.2 strain MT586027.1 in a relatively independent sub-branch. The results of the recombination analysis showed that the strain was recombined from the MT586027.1 (major parent) and MN90145.1 (minor parent) strains, and recombination breakpoints were at locations in the 2858-5137 nt range.
The results of this study extend our understanding of the molecular epidemiology of GI.2.
2020年5月，中国四川省发生了由兔出血症病毒2型（RHDV2，GI.2）引起的兔出血症2型（RHD2）疫情。该病急性起病且病程短，导致兔死亡率高达42.86%。目前，中国缺乏关于GI.2病因及基因特征的基础研究。
研究了感染兔各组织的病理变化并对病毒基因组进行了特征分析。本研究采用逆转录聚合酶链反应（RT-PCR）、组织病理学和扫描电子显微镜技术，对感染死亡兔的样本进行病原体鉴定。基于全基因组序列分析构建系统发育树，并分析重组事件。
RT-PCR鉴定出存在GI.2。组织病理学显示肝细胞坏死和肺泡出血。电子显微镜显示GI.2颗粒呈球形，大小为40纳米。分离株的基因序列长度为7445碱基对（GenBank登录号MW178244）。基于分离株基因组与60个参考株的系统发育分析表明，该分离株与GI.2株MT586027.1聚集在一个相对独立的亚分支中。重组分析结果显示，该毒株由MT586027.1（主要亲本）和MN90145.1（次要亲本）毒株重组而成，重组断点位于2858 - 5137核苷酸范围内。
本研究结果扩展了我们对GI.2分子流行病学的认识。
