鸡呼肠孤病毒基因I型变异株的分离鉴定和致病性分析

Isolation,Identification and Pathogenicity Analysis of Avian Reovirus GenotypeⅠVariants

为探究导致山东省某肉种鸡场种鸡出现腿病的病原并进行致病性分析,本试验从该肉种鸡场收集病料,进行鸡胚分离、细胞传代、反转录-聚合酶链反应(RT-PCR)检测、序列分析、商品肉鸡的致病性试验和免疫攻毒保护试验。结果显示,分离获得1株鸡呼肠孤病毒(ARV),命名为ARV-LL-2020,该病毒对鸡胚的致死率为100%,在鸡肝癌细胞系(LMH)上具有较强的适应性。ARV-LL-2020毒株与经典的S1133疫苗株同属基因Ⅰ型,但两者的主要抗原σC基因的核苷酸同源性为73.6%,氨基酸同源性为59.1%。ARV-LL-2020毒株回归商品肉鸡能复制出与实际生产中完全一致的发病症状。S1133株商品化弱毒活疫苗对ARV-LL-2020毒株的保护率仅有50%。结果表明,导致种鸡腿病的ARV-LL-2020毒株是1株ARV基因I型变异株,目前S1133株商品化弱毒活疫苗无法对其提供完全保护。

This study aimed to investigate the pathogen responsible for leg problems observed in broiler breeders at a chicken farm in Shandong Province,and to analyze its pathogenicity.Samples were collected from the affected chicken farm,and the investigation included embryonic chicken isolation,cell passage,reverse transcription-polymerase chain reaction(RT-PCR)detection,sequence analysis,pathogenicity tests on commercial broiler chickens,and immunoprotection assays.The results revealed the isolation of a strain of avian reovirus(ARV),named ARV-LL-2020,which exhibited 100%mortality in embryonic chickens and strong adaptability in Leghorn male hepatoma cell line(LMH).The ARV-LL-2020 strain belongs to genotype I,similar to the classical S1133 vaccine strain,with 73.6%nucleotide homology and 59.1%amino acid homology in the major antigenσC gene.In commercial broiler chickens,ARV-LL-2020 replicated symptoms identical to those observed in actual production settings.The commercial attenuated live vaccine strain S1133 provided only 50%protection against ARV-LL-2020.These findings indicate that ARV-LL-2020 strain causing chicken leg problems is a variant strain of avian reovirus genotype I,and the current commercial attenuated live vaccine S1133 does not provide complete protection against it.