云南省部分地区牛冠状病毒检测及其N基因序列分析

Detection of Bovine Coronavirus and Analysis on Its N Gene Sequence in Some Areas of Yunnan Province

为深入了解云南省牛冠状病毒(bovine coranarirus,BCoV)在不同地区、不同年龄牛群中的流行情况,2021-2022年采集大理、陆良、石林、寻甸等4个地区5家牛场不同年龄牛的粪便样品357份(腹泻样品61份、非腹泻样品296份)进行BCoV RT-PCR检测,并对BCoV阳性样品进行N基因测序分析。结果显示:在357份粪便样品中,检出BCoV阳性51份,总样品检出率为14.29%,5家牛场均有阳性检出,场阳性率为100%;1周龄、1周龄-1月龄、1~6月龄、1岁以上牛粪便样品的BCoV检出率分别为10.00%、19.23%、10.81%、17.31%;腹泻样品BCoV检出率为36.07%,非腹泻样品为9.78%。通过扩增得到4条完整的BCoVN基因序列;经同源性与遗传进化分析,4条N基因序列高度保守,相互间核苷酸同源性为99.0%~99.8%,与国内参考毒株处于同一小分支,亲缘关系近,核苷酸同源性为97.7%~99.9%,与美国4-17-03、7-16-23、4-17-25和日本GF2020等毒株处于同一个大分支且遗传距离较近;与美国原始毒株Mebus处于不同的大分支,亲缘关系较远,核苷酸同源性为98.1%~98.2%。结果表明:云南省牛群中可能广泛存在BCoV流行,1周龄—1月龄犊牛感染发病风险最高,调运或引种导致BCoV在国内传播的可能性较大。因此,需加强BCoV流行的监测与控制,严格进行检疫,加快疫苗研发和应用。

In order to investigate the prevalence of bovine coronavirus(BCoV) in different regions and cattle population at different ages in Yunnan Province,357 fecal samples(61 diarrhea and 296 non-diarrhea samples)were collected from the cattle at different ages in 5 farms in Dali,Luliang,Shilin and Xundian from 2021 to 2022 to detect BCoV by RT-PCR,followed by analysis on the N gene sequence for BCoV positive samples.The results showed that,for the 357 samples,51 positive samples were detected,with a total detection rate of 14.29%,and they were from all the 5 farms,with a farm positive rate of 100%;the detection rates of the samples from the cattle at 1 week old,1 week to 1 month old,1 to 6 months old and over 1 year old were 10.00%,19.23%,10.81% and17.31% respectively;those of diarrhea and non-diarrhea samples were 36.07% and 9.78%,respectively.Four complete BCoV N gene sequences were obtained by amplification,which,by analysis on homology and genetic evolution,were highly conserved,with a nucleotide homology from 99.0% to 99.8%,locating at the same sub-branch with the domestic reference strain,with close genetic relationship and the nucleotide homology from 97.7% to 99.9%;they were at the same large branch with American strain 4-17-03,7-16-23,4-17-25 and Japanese strain GF2020,with a close genetic distance;but they were at different large branch with American original strain Mebus,with a distant genetic relationship and the nucleotide homology from 98.1% to 98.2%.In conclusion,BCoV might be widely prevalent in the cattle population in Yunnan Province,especially the calves at 1 week to 1 month old,which might be caused by transportation or introduction.Therefore,it was necessary to strengthen the monitoring,control and quarantine against the virus,and speed up the development and application of corresponding vaccines.