一例狐狸犬瘟热免疫失败病例的病毒分离及病因分析  

Virus isolation and etiological analysis of a case with canine distemper vaccination failure in a fox

作　　者：宋伶伶 李贝影 吴佳琦[1] 单虎[1] 黄娟[1] SONG Lingling;LI Beiying;WU Jiaqi;SHAN Hu;HUANG Juan(College of Veterinary Medicine,Qingdao Agricultural University,Qingdao 266109,China)

机构地区：[1]青岛农业大学动物医学院,山东青岛266109

出　　处：《畜牧与兽医》2023年第8期104-111,共8页Animal Husbandry & Veterinary Medicine

基　　金：国家自然科学基金(31472196)。

摘　　要：为了分析犬瘟热免疫失败的原因,以一例发病前曾接种过犬瘟热弱毒疫苗的幼龄狐狸犬瘟热疑似病例为研究对象,进行了病毒分离鉴定和全基因组测序分析,并将分离得到的犬瘟热病毒(CDV)分别接种有母源抗体和无母源抗体的两组家犬,观察该分离毒株对家犬的致病性。结果显示:分离毒在Vero-SLAM细胞上形成合胞体病变,抗原快速检测卡检测显示CDV阳性,犬冠状病毒和犬细小病毒均为阴性。系统发育分析表明该毒株与疫苗毒株的遗传距离较远,进化上属于野毒株谱系中的亚洲1型。与疫苗株CDV3相比,该毒株在H蛋白和F蛋白上分别多了2个和1个潜在的糖基化位点,且F蛋白上一个预测的切割位点RRQRR突变成RRQKR。该分离毒在接种13 d后引起没有母源抗体的幼犬死亡,而有母源抗体的幼犬仅发生一过性感染。结论:成功从免疫失败病例中分离到CDV,幼狐在免疫空白期感染CDV是该病例免疫失败的可能原因。该发现为目前犬瘟热的免疫失败及分子流行病学研究提供了更多的理论依据。In order to analyze the causes of vaccination failure of canine distemper,a suspected case of canine distemper in a young fox who had been vaccinated with canine distemper attenuated vaccine before the onset of the disease was taken as the research subject.Virus isolation and whole genome sequencing were conducted.Then,the isolate was inoculated into two groups of dogs with and without maternal antibody,respectively,and the pathogenicity of the isolated virus strain to the dogs was observed.The results showed that the isolated virus formed syncytial lesions on Vero-SLAM cells.The rapid detection card of antigen showed positive for canine distemper virus,negative for canine coronavirus and canine parvovirus.The phylogenetic analysis showed that the genetic distance between the isolate and the vaccine strains was far,and the isolate belonged to the Asia-1 genotype of wild virus lineage in evolution.Compared with the vaccine strains,this isolate had 2 and 1 more potential glycosylation sites on the H protein and the F protein,respectively,and a predictable cleavage site(RRQRR)at the F protein was mutated into RRQKR.The isolated virus killed the puppies without maternal antibody 13 days post inoculation(dpi);however,the puppies with maternal antibodies had a transient infection only.It might be concluded that a canine distemper virus was successfully isolated from the immunization failure case,the field virulent virus infection during the immune gap contributed to the vaccination failure of the young fox.These findings provided a comprehensive understanding of the current vaccination failure and the molecular epidemiology of canine distemper in China.

关 键 词：犬瘟热病毒 免疫失败 母源抗体 基因序列分析 

分 类 号：S852[农业科学—基础兽医学]