蛋鸡禽腺病毒4型流行毒株SX17株的分离与鉴定

从陕西渭南蛋鸡场疑似心包积液-肝炎综合征病例中分离鉴定病原,并研究其致病性与分子特征,为防控心包积液-肝炎综合征提供参考。采集并处理临床样品,通过SPF鸡胚绒毛尿囊膜接种传代分离病毒,测定分离毒株的血凝性和鸡胚半数致死量(ELD50),进行攻毒试验、组织病理观察和病毒在不同组织中的分布检测,测定hexon基因序列并比对分析。结果显示,病毒传至第5代后鸡胚死亡出现规律性,鸡胚不同部位病毒分布检测发现肝脏、卵黄囊、尿囊液和绒毛尿囊膜中有病毒分布,将获得的病毒命名为SX17株。血凝性测定结果表明,SX17株对鸡、鸭、鹅红细胞均无血凝特性;测得ELD50为10-3.54/0.1 mL;攻毒2 d后试验鸡陆续出现临床症状,病理组织学检查肝脏、脾脏、心脏和肾脏均有典型变化;攻毒死亡鸡只肝脏、肠道、心包积液和肾脏中有病毒分布,在肌肉、粪便、心肌、肺脏和气管中未检测到病毒核酸。hexon基因序列比对提示SX17株为FAdV-4型流行毒株。结果表明,鸡胚分离血清4型禽腺病毒可收获肝脏、卵黄囊、绒毛尿囊膜和尿囊液,临床病例样品采集以肝脏、肠道、心包积液和肾脏为佳,分离到的SX17株为致病性较强的FAdV-4型流行毒株。

Isolation and Identification of a Pandemic FAdV-4 Type Strain SX17

To isolate and identify pathogens from suspected pericardial effusion-hepatitis syndrome cases in chicken farms in Weinan city Shaanxi province,and to study its pathogenicity and molecular characteristics,and provide reference for prevention and control of pericardial effusion-hepatitis syndrome,the clinical samples were collected and processed,and the virus was isolated by SPF chick chorioallantoic membrane inoculation.The hemagglutination and the chicken embryo half lethal dose(ELD50)of the isolated strains were determined,and the challenge test,histopathological observation,distribution detection in different tissues,determination of hexon gene sequences and alignment analysis were performed.The results showed that the death of chicken embryos after the passage of the fifth generation was regular.The distribution of virus in different parts of chicken embryos showed in liver,yolk sac and allantoic fluid,and the virus was named SX17 strain.The results of hemagglutination test showed that the SX17 strain had no hemagglutination properties on chicken,duck and goose red blood cells;the ELD50 was measured to be 10-3.54/0.1 mL;the clinical symptoms of the test chickens appeared after 2 days of challenge,and the histopathological examination of the liver,spleen,heart and kidney showed typical lesions.The liver and intestinal were the most widely distributed in the dead chickens,and there was also a low load distribution in the pericardial effusion and the kidney.No viral nucleic acid was detected in muscle,feces,myocardium,lung and trachea.The hexon gene sequence alignment indicated that the SX17 strain was a prevalent strain of FAdV-4 type.This study showed that the liver,yolk sac,allantocherion and allantoic fluid can be used to harvest the serotype 4 avian adenovirus from chicken embryo.The clinical samples,collected from the liver and intestine,were suitabe to isolate the virus,and the isolated SX17 strain is a pathogenic strain of FAdV-4.