兰州市及周边地区禽白血病病毒的分子流行病学调查

Molecular epidemiological investigation of avian leucosis virus in Lanzhou and its neighboring area

为了解兰州市及周边地区禽白血病的流行情况及流行毒株的分子特征,从该地区11个鸡场和2个屠宰场采集抗凝鸡血1 294份,应用自建的禽白血病病毒(ALV)A、B、J亚群多重PCR诊断方法检测了A、B、J亚群的感染率与分布,进行了各亚群流行毒株gp85基因的序列分析。从1 294份样品中,共检出外源性ALV 486份,平均检出率为37.56%。其中检出ALV-A亚群16份,感染率为1.24%;ALV-J亚群383份,感染率为29.60%;ALV-A/J亚群68份,感染率为5.26%;ALV-B/J亚群19份,感染率为1.47%。序列分析表明,J亚群流行株gp85基因的核苷酸序列的同源性介于98%～100%,与J亚群英国毒株HPRS-103、美国毒株ADOL-7501、国内分离株SD9902、本实验室保存毒株(JX1、JX2、AH2和GZ1)间的同源性分别为97%～98%、86%～88%、96%～97%、98%～100%。在J亚群流行株中,发现gp85基因有13个核苷酸突变型,在共104个碱基置换中71个为异义突变、33个为同义突变,可区分为8个氨基酸突变型,突变位点主要集中在第200～400bp、第500～600bp范围的核苷酸之内和第120～240aa内。gp85基因进化关系分析表明,本地区J亚群流行株的8个氨基酸突变型均与英国毒株HPRS-103及国内分离株JX1、JX2、AH1和GZ1处于同一进化树分支。调查结果表明,兰州市及周边地区外源性禽白血病病毒感染现象较为严重且以J亚群为主,部分鸡场也可同时检出A、B亚群。

To understand the prevalence and molecular characteristics of epidemic strains of avian leucosis in Lanzhou and its neighboring area,1 294 samples were collected from 11 chicken farms and 2 slaughterhouses for detecting the disease using a subgroup A/B and J targeting multiplex PCR developed by our laboratory.Out of 1 294 samples,486 were detected with detection rate of 37.56%.Among these,A subgroup infection rate was 1.24%（16/1 294）,J subgroup infection rate was 29.60%（383/1 294）,A/J subsets infection rate was 5.26%（68/1 294）,and B/J subsets infection rate was 1.47%（19/1 294）.Sequence analysis showed that the identities of J subgroup in this study were from 98% to 100% on the basis of gp85,which showed similarities 97% to 98%,from 86% to 88%,from 96% to 97%,and from 98% to 100% when compared with English strain HPRS-103,USA strain ADOL-7501,Chinese isolate SD9902 and our laboratory strains（JX1,JX2,AH2 and GZ1）,respectively.Thirteen types of mutation in gp85 gene were found in subgroup J strains,in which total of 104 base substitutions were identified that include,71 missense mutations and 33 silent mutations.Consequently,eight amino acid mutations were caused.The mutation sites were mainly concentrated in the ranges on nucleotide sequence from 200 bp to 400 bp and from 500 bp to 600 bp respectively.Evolutionary relationship analysis using amino acid of gp85 from eight mutants showed that the epidemic strains of subgroup J were in the same evolutionary branch with strain HPRS-103 and the domestic isolates JX1,JX2,AH1 and GZ1.The investigation showed that exogenous avian leucosis virus infection is serious in Lanzhou and its neighboring area;the A and B subsets of subgroup J were found at the same farms in some cases.