山东地区犬冠状病毒的分子流行病学调查及其基因型多样性分析

Prevalence and genotypic diversity of canine coronavirus in Shandong Province

摘要:

【目的】了解分析山东地区健康犬及腹泻犬中犬冠状病毒(CCoV)的分子流行病学及其基因型。【方法】采集2017年以来山东省宠物市场、流浪犬中心、犬舍、各地宠物医院等的健康和腹泻犬只的肛拭子样品，采用PCR方法检测CCoV及其CCoV-Ⅰ和CCoV-Ⅱ(CCoV-Ⅱa和CCoV-Ⅱb)基因分型情况，并对扩增出的M、S全基因进行测序分析。【结果】199份样品中，共检出CCoV阳性样品79份，健康犬中的检出率为40.2%(33/82)，腹泻犬中的检出率为39.3%(46/117)。健康犬中CCoV-Ⅰ型与CCoV-Ⅱ型阳性检出率分别为78.8%(26/33)和51.5%(17/33)；腹泻犬中CCoV-Ⅰ型与CCoV-Ⅱ型阳性检出率分别为39.13%(18/46)和80.4%(37/46)。基因型阳性比率分析表明，健康犬中单独感染CCoV-I型的比率最高，为48.5%(16/33)；腹泻犬中单独感染CCoV-Ⅱa比率最高，为47.8%(22/46)。测序分析获得48株M基因序列，遗传进化分析表明，12株CCoV-Ⅰ型毒株中除1株外，其余均从健康犬中分离。36株CCoV-Ⅱ型毒株中除7株来自健康犬外，其余均为腹泻犬中获得。获得的3株S全基因均来自腹泻犬且均属于CCoV-Ⅱa亚型。【结论】山东地区犬群中CCoV检出率较高，说明CCoV广泛流行，健康犬和腹泻犬中均存在多重感染情况，健康犬中主要流行CCoV毒株为CCoV-Ⅰ型，腹泻犬中主要流行CCoV-Ⅱa型。

关键词:犬冠状病毒;基因型;M基因;S基因;序列分析

Abstract:

[Objective] To learn the prevalence and genotypic diversity of canine coronavirus (CCoV) in healthy and diarrhea dogs in Shandong Province. [Methods] We collected 199 anal swabs from healthy and diarrhea dogs in pet markets, stray dog centers, kennels, and pet hospitals in Shandong Province since 2017. CCoV was detected and genotyped by PCR method, and then the amplified M and S genes were sequenced and analyzed. [Results] Among the 199 anal swabs, 79 were CCoV-positive. The positive rate of CCoV was 40.2% (33/82) in healthy dogs and 39.3% (46/117) in diarrhea dogs. The positive rates of CCoV-Ⅰ and CCoV-Ⅱ were 78.8% (26/33) and 51.5% (17/33) in healthy dogs, and 39.13% (18/46) and 80.4% (37/46) in diarrhea dogs, respectively. CCOV-Ⅰ had the highest single infection rate (48.5%, 16/33) in healthy dogs, while CCoV-Ⅱ had the highest single infection rate (47.8%, 22/46) in diarrhea dogs. The M gene sequences of 48 strains were determined by sequencing analysis. Phylogenetic analysis showed that 11 out of the 12 CCoV-Ⅰ strains were isolated from healthy dogs. Among the 36 CCoV-Ⅱ strains, 7 strains were isolated from healthy dogs and the rest from diarrhea dogs. The 3 strains with whole S gene and obtained from diarrhea dogs all belonged to CCoV-Ⅱ.[Conclusion] The high positive rate of CCoV in the dogs in Shandong Province indicates that the virus is widely prevalent. Multiple infections exist in both healthy and diarrhea dogs. The main prevalent CCoV type is CCoV-I in healthy dogs and CCoV-Ⅱa in diarrhea dogs.

Key words:canine coronavirus;genotype;M gene;S gene;sequence analysis