清远麻鸡禽白血病病毒感染特点及其受体基因序列多态性分析

Characteristics of avian leukosis virus infection and polymorphism analysis of receptor gene sequence in Qingyuan Ma chickens

为了解目前不同清远麻鸡规模化种鸡场外源性禽白血病病毒(avian leukosis virus,ALV)感染特点及其受体基因Tva、Tvb及NHE1序列多态性,本研究对5个清远麻鸡种鸡场进行外源性ALV病毒分离鉴定和受体基因扩增及测序分析。病毒分离及亚群鉴定结果显示:A、B、C 3个场的外源性ALV病毒分离阳性率均低于5%,其中A场存在ALV-J单独感染,B场存在ALV-J和ALV-K混合感染,C场存在ALV-K单独感染,而D场和E场未检测出外源性ALV感染。受体基因多态性分析显示:A~E场均存在不同频率的Tvar 3、Tvar 4和Tvbr 3抗性等位基因,Tvar 3的分布频率为0.2~0.6,Tvar 4的分布频率为0.3~0.7,Tvbr 3的分布频率为0.1~0.7。此外,B场和D场还存在Tvar 5抗性等位基因,分布频率均为0.2。NHE1受体基因序列发生18个SNP突变,其中1279、1361、1369、1406、1442、1912位为非同义突变,可引起氨基酸发生改变。结果表明,5个清远麻鸡规模化种鸡场外源性ALV感染率和亚群有差异,各场应该有更针对性的独特净化策略;不同频率的Tva和Tvb抗性等位基因分布以及NHE1基因发生的6个非同义突变使清远麻鸡具有一定的遗传抗性选育的潜力。

In order to understand the characteristics of avian leukosis virus(ALV)infection and the polymorphisms of receptor genes Tva,Tvb and NHE1sequences in different Qingyuan Ma chicken breeding farms,the isolation and identification of exogenous ALV virus,receptor gene amplification and sequencing analysis were carried out in five Qingyuan Ma chicken breeding farms.The results of virus isolation and subtype identification showed that the positive rate of exogenous ALV virus isolation in farms A,B and C was less than 5%,among which there was ALV-J infection alone in farm A,mixed infection with ALV-J and ALV-K in farm B,ALV-K infection alone in farm C,and no exogenous ALV infection was detected in farm D and E.Polymorphism analysis of recipient genes showed that there were different frequencies of Tvar3,Tvar4 and Tvbr3 resistance alleles in A-E farms,and the distribution frequency of Tvar3 was 0.2-0.6,the distribution frequency of Tvar4 was 0.3-0.7,and the distribution frequency of Tvbr3 was 0.1-0.7.In addition,there were Tvar5 resistance alleles in both B and D farms,with a distribution frequency of 0.2.A total of 18SNP mutations occurred in the NHE1receptor gene sequence,and further analysis showed that positions 1279,1361,1369,1406,1442,and 1912were non-synonymous mutations,which could cause changes in amino acids.The study suggested that there were differences in the exogenous ALV and its subtypes among the five Qingyuan Ma chicken breeders,and each farm should have a more targeted and unique purification strategy.The distribution of Tva and Tvb resistance alleles at different frequencies,along with the occurrence of 6non-synonymous mutations in the NHE1gene,indicate that Qingyuan Ma chicken have the potential of genetic resistance breeding.