Institute for Poultry Science and Health, Guangxi University, Nanning, Guangxi, 530005, China.
School of Marine Sciences and Biotechnology/Guangxi Key Laboratory Cultivation Base for Polysaccharide Materials and Modifications, Guangxi University for Nationalities, Nanning, Guangxi 530006, China.
Vet Microbiol. 2020 Jul;246:108723. doi: 10.1016/j.vetmic.2020.108723. Epub 2020 May 19.
Duck spleen necrosis disease (DSND) is an emerging infectious disease that causes significant economic loss in the duck industry. In 2018, a duck reovirus (named DRV/GX-Y7) and Salmonella indiana were both isolated from the spleens and livers of diseased ducks with DSND in China. The DRV/GX-Y7 strain could propagate in the Vero, LMH, DF-1 and DEF cells with obvious cytopathic effects. The genome of DRV/GX-Y7 was 23,418 bp in length, contained 10 dsRNA segments, ranging from 3959 nt (L1) to 1191 nt (S4). The phylogenetic analysis showed that the DRV/GX-Y7 strain was in the same branch with the new waterfowl-origin reovirus cluster, but was obviously far distant from the clusters of other previous waterfowl-origin reoviruses Muscovy duck reovirus (MDRV) and goose-origin reovirus (GRV), broiler/layer-origin reovirus (ARV) and turkey-origin reovirus (TRV). The RDP and SimPlot program analysis revealed that there were two potential genetic reassortment events in the M2 and S1 segments of the genome. In order to have a clear insight into the pathogenic mechanism of DRV/GX-Y7 and S. Indiana in clinical DSND, an infection experiment was further conducted by challenging commercial ducklings with the two isolates individually and with both. The results showed that DRV/GX-Y7 produced severe hemorrhagic and/or necrotic lesions in the immune organs (thymus, spleen, and bursae) of experimentally infected ducklings. And, that the co-infection of DRV/GX-Y7 and S. Indiana could greatly enhance the pathogenesis by increasing the morbidity and mortality in ducklings whose clinical symptoms and lesions were similar to the natural clinical DSND cases. In summary, the results suggested that the pathogen causing duck spleen necrosis was an emerging unique genetic reassortment strain of duck Orthoreovirus that was significantly different from any previously reported waterfowl-derived Orthoreovirus and the co-infection with the Salmonella isolate could increase the severity of the disease.
鸭脾坏死病（DSND）是一种新兴的传染病，给养鸭业造成了重大的经济损失。2018 年，在中国，从患有 DSND 的病鸭的脾脏和肝脏中分离到了鸭呼肠孤病毒（命名为 DRV/GX-Y7）和印第安纳沙门氏菌。DRV/GX-Y7 株在 Vero、LMH、DF-1 和 DEF 细胞中能有效增殖，且具有明显的致细胞病变效应。DRV/GX-Y7 的基因组全长 23418 bp，包含 10 个 dsRNA 片段，大小从 3959 nt（L1）到 1191 nt（S4）不等。系统进化分析显示，DRV/GX-Y7 株与新型水禽源呼肠孤病毒聚类在同一分支，但与先前水禽源呼肠孤病毒（Muscovy duck reovirus，MDRV 和 goose-origin reovirus，GRV）、肉鸡/蛋鸡源呼肠孤病毒（broiler/layer-origin reovirus，ARV 和 turkey-origin reovirus，TRV）聚类明显较远。RDP 和 SimPlot 程序分析显示，基因组的 M2 和 S1 片段存在两个潜在的遗传重组事件。为了深入了解 DRV/GX-Y7 和 S. Indiana 在临床 DSND 中的致病机制，进一步通过单独和混合感染两种分离株对商业雏鸭进行了感染实验。结果表明，DRV/GX-Y7 在实验感染雏鸭的免疫器官（胸腺、脾脏和法氏囊）中产生了严重的出血和/或坏死病变。而且，DRV/GX-Y7 和 S. Indiana 的共同感染可以通过增加雏鸭的发病率和死亡率来极大地增强发病机制，其临床症状和病变与自然发生的临床 DSND 病例相似。综上所述，结果表明引起鸭脾坏死的病原体是一种新型独特的鸭呼肠孤病毒遗传重组株，与任何先前报道的水禽来源呼肠孤病毒明显不同，与沙门氏菌分离株的共同感染会增加疾病的严重程度。
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