Shen Huigang, Zhang Jianfeng, Gauger Phillip C, Burrough Eric R, Zhang Jianqiang, Harmon Karen, Wang Leyi, Zheng Ying, Petznick Thomas, Li Ganwu
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
Key Laboratory of Livestock Disease Prevention of Guangdong Province, Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
Transbound Emerg Dis. 2022 May;69(3):1246-1255. doi: 10.1111/tbed.14087. Epub 2021 May 5.
Porcine sapovirus (SaV) was first identified by electron microscopy in the United States in 1980 and has since been reported from both asymptomatic and diarrhoeic pigs usually in mixed infection with other enteric pathogens. SaV as the sole aetiological agent of diarrhoea in naturally infected pigs has not previously been reported in the United States. Here, we used four independent lines of evidence including metagenomics analysis, real-time RT-PCR (rRT-PCR), histopathology, and in situ hybridization to confirm porcine SaV genogroup III (GIII) as the sole cause of enteritis and diarrhoea in pigs. A highly sensitive and specific rRT-PCR was established to detect porcine SaV GIII. Examination of 184 faecal samples from an outbreak of diarrhoea on a pig farm showed that pigs with clinical diarrhoea had significantly lower C values (15.9 ± 0.59) compared to clinically unaffected pigs (35.8 ± 0.71). Further survey of 336 faecal samples from different states in the United States demonstrated that samples from pigs with clinical diarrhoea had a comparable positive rate (45.3%) with those from asymptomatic pigs (43.1%). However, the SaV-positive pigs with clinical diarrhoea had significantly higher viral loads (C = 26.0 ± 0.5) than the SAV-positive but clinically healthy pigs (C = 33.2 ± 0.9). Phylogenetic analysis of 20 field SaVs revealed that all belonged to SaV GIII and recombination analysis indicated that intragenogroup recombination had occurred within the field isolates of SaV GIII. These results suggest that porcine SaV GIII plays an important aetiologic role in swine enteritis and diarrhoea and rRT-PCR is a reliable method to detect porcine SaV. Our findings provide significant insights to better understand the epidemiology and pathogenicity of porcine SaV infection.
猪札幌病毒（SaV）于1980年在美国首次通过电子显微镜鉴定出来，此后在无症状和腹泻猪中均有报道，通常与其他肠道病原体混合感染。在美国，此前尚未报道过猪札幌病毒作为自然感染猪腹泻的唯一病原体。在此，我们使用了包括宏基因组学分析、实时逆转录聚合酶链反应（rRT-PCR）、组织病理学和原位杂交在内的四条独立证据线，以确认猪札幌病毒基因组III型（GIII）是猪肠炎和腹泻的唯一病因。建立了一种高度灵敏且特异的rRT-PCR方法来检测猪札幌病毒GIII型。对一个养猪场腹泻疫情的184份粪便样本进行检测发现，临床腹泻猪的C值（15.9±0.59）显著低于未受临床影响的猪（35.8±0.71）。对来自美国不同州的336份粪便样本进行的进一步调查表明，临床腹泻猪的样本阳性率（45.3%）与无症状猪的样本阳性率（43.1%）相当。然而，临床腹泻的猪札幌病毒阳性猪的病毒载量（C=26.0±0.5）显著高于猪札幌病毒阳性但临床健康的猪（C=33.2±0.9）。对20株田间猪札幌病毒进行系统发育分析表明，所有毒株均属于猪札幌病毒GIII型，重组分析表明在猪札幌病毒GIII型的田间分离株中发生了基因组内重组。这些结果表明，猪札幌病毒GIII型在猪肠炎和腹泻中起重要病因作用，rRT-PCR是检测猪札幌病毒的可靠方法。我们的研究结果为更好地了解猪札幌病毒感染的流行病学和致病性提供了重要见解。
