H3N2犬流感病毒PB2 E^(627)K突变对小鼠致病性的影响

Effect of PB2 E^(627)K on the pathogenicity of H3N2 canine influenza virus in mice

甲型流感病毒PB2蛋白627位点突变(E^(627)K)是影响流感病毒宿主适应性和致病性的重要因素之一。本实验室前期研究分离的H3N2亚型犬流感病毒(CIV)GD02株(A/canine/Guangdong/02/2011)PB2蛋白序列的627位点氨基酸为谷氨酸,为研究该病毒株PB2的E^(627)K突变对小鼠致病性的影响,本实验采用反向遗传操作技术获得rGD02,并利用定点突变技术拯救了PB2 627位点发生突变的rGD02-E^(627)K。通过接种小鼠比较rGD02和rGD02-E^(627)K对小鼠致病性的差异,评价PB2 E^(627)K突变对H3N2 CIV致病性的影响。结果显示,rGD02和rGD02-E^(627)K对小鼠均无致死性(MLD50>106EID50),对小鼠增重的影响差异均不显著,而且这两株病毒对小鼠的致病性也无明显差异。表明PB2 E^(627)K并未显著影响H3N2 CIV对小鼠的致病性,该研究建立的H3N2 CIV反向遗传操作平台和定点突变技术为该病毒后续的致病机理、基因功能研究及疫苗研制奠定了基础。

Substitution of lysine at 627 position in PB2 protein （E^627K） has been recognized as a determinant for host adaptation and virulent element for influenza A viruses. The H3N2 subtype canine influenza virus （CIV） of A/canine/Guangdong/ 02/2011 （GD02） isolated by this Lab possessed a glutamic acid （627E） in PB2. To explore the potential role of E6ZTK substitution in PB2 in the H3N2 CIV, we compared the biology properties and pathogenicity in mice between the rescued virus rGD02 containing mE in PB2 and the mutation virus rGD02-E^627K containing 627K. The rGD02 and rGD02-E^627K were rescued by the GD02 reverse genetic system and site-directed mutation technology. Then, rGD02 and rGD02-E^627K pathogenicity were tested in mice to evaluate the PB2 E^627K mutation influence of H3N2 CIV on the pathogenicity. The results showed that both rGD02 and rGD02-ETK were not fatal to mice（MLD50〉10^6 EID50） and had limited effects on mice body weight, indicating that the pathogenicity of rGD02 and rGD02-E^627K to mice were no significant difference. The studies suggested a ^627K substitution in PB2 had on impact on the pathogenic for the H3N2 CIV to mice.