鸡源血清4型禽腺病毒的分离鉴定与组织灭活苗免疫效果研究

Isolation and Identification of a Fowl Adenovirus Serotype 4 Strain from Chicken Broilers and Efficacy of Inactivated Tissue Vaccine

山东某养殖场肉鸡发生以心包积液、出血性肝炎为特征的疾病,临床初步诊断为心包积液综合征,为确诊该病,我们通过病毒鸡胚培养、PCR扩增测序、Hexon基因序列比对与同源性分析及动物回归试验等对病毒培养物进行鉴定,确定分离株为血清4型禽腺病毒,毒株Hexon基因序列与公开发表的FAdV-4型代表株处于同一分支上,动物回归试验能完全复制出与自然感染鸡相同的症状与病变。取病死鸡肝组织制备组织灭活苗,免疫后测定琼扩抗体并进行免疫保护试验,结果显示:免疫后14 d可检测到琼扩抗体(40%),至21 d抗体阳性率达100%;接种后4 d开始产生保护(25%),21 d可产生完全保护;对发病鸡群进行紧急接种,可在6 d左右完全控制本病。该研究结果为探究我国FAdV的分子流行情况与防控提供了基础材料和理论依据。

A disease characterized as sudden death,hydropericardium and liver necrosis emerged on a chicken farm in Shandong province.In order to diagnose this case,the liver samples were collected from dead chickens for virus isolation by embryo inoculation and the isolated virus were characterized by PCR,Hexon gene sequencing,homology analysis and animal inoculation.The results showed that the isolated virus belonged to Fowl adenovirus type 4(FAdV-4).The hexon gene sequence of this isolate was grouped in the same branch as the published FADV-4 representative strain.Animal experiment reproduced the same clinical signs and pathological changes as naturally infected chickens.In order to prevent and control the disease,an inactivated tissue vaccine was prepared using livers of dead chickens and tested for its immunoprotective effect.Blood samples were collected at 4,7,14 and 21 days post immunization to detect their antibodies by AGP detection.At the same time,the vaccinated chickens were challenged to observe the protective effect.The results showed that the antibody was detected 14 days post immunization(40%),and the antibody positive rate reached 100%at 21 days.The onset of protection was observed in 25%chickens at 4 days post immunization(25%),and then protection rates increased to 40%,80%and 100%at 7,14 and 21 days.In addition,the emergency vaccination for other chickens completely stopped the disease in 6 days.