鸡体内疫苗抗体选择压对H9N2亚型禽流感病毒内部基因演化的影响

Effects of Vaccine Antibody Selection on The Internal Genetic Evolution of H9N2 Subtype Avian Influenza Virus in Chickens

在我国,接种疫苗是防控H9N2亚型禽流感(Avain influenza,AI)流行的主要措施。为了解H9N2亚型禽流感病毒(Avain influenza virus,AIV)在疫苗抗体选择压下的遗传变异情况,本研究选择A/Chicken/Shanghai/F/98(H9N2,F/98)禽流感病毒分别在有和没有疫苗抗体选择压的SPF鸡体内连续传代。为了减少混合病毒对研究结果的干扰,我们建立了三个独立传代系列。结果表明,母本病毒在经过有和没有疫苗抗体选择压下连续传代后,两种模式下的传代病毒的内部基因都发生了基因突变。与没有疫苗抗体选择压下的传代病毒相比,有疫苗抗体选择压下的传代病毒氨基酸突变数量明显减少(P<0.05),肺组织分离到的传代病毒的突变氨基酸数量显著多于相同传代条件下气管中分离到的传代病毒的氨基酸突变数量(P<0.05)。此外,疫苗抗体选择压下的传代病毒V9L和V9T有4个特有突变:PB2(H366Q、A322E)和M(P154A、A246Q),没有疫苗抗体选择压下的传代病毒N9L和N9T有9个相同突变:PB2(I298Q、E526R)、PB1(T348A)、PA(L336M)、NP(G52A、L187G)、M(H23I)和NS(S81L、H85S),所有第9代次的传代病毒相同的突变有2个:PB2(R327K、Y369S)。值得注意的是,相比母本病毒没有疫苗抗体选择压下的传代病毒对鸡胚的感染力显著提高(P<0.01),而有免疫选择压下的传代病毒对鸡胚的感染力相比母本病毒变化不大(P>0.05),但丧失了致死鸡胚的能力。本研究对了解禽流感病毒在疫苗的选择压力下的演化规律,以及理解疫苗对病毒进化的影响具有重要参考意义。

In China,vaccination is the main strategy to prevent the epidemic of H9N2 avian influenza. To understand the genetic variation of H9N2 avian influenza virus(AIV) under vaccine antibody selection,A/Chicken/Shanghai/F/98(H9N2,F/98)avian influenza virus was serially passaged in specific pathogen free(SPF)chickens with and without vaccine antibody selection pressure. In this study,three separate generational series were established. The results showed that the number of amino acid mutations in the passaged virus with vaccine antibody selection was significantly less than that in the passaged virus without vaccine antibody selection(P<0.05). The number of amino acid mutations in passaged virus isolated from lung tissue was more than that in passaged virus isolated from the trachea in the same passage conditions(P<0.05). All passaged viruses(the 9th generation)had two mutations in common:R327K and Y369S in PB2 gene. Viruses V9L and V9T passaged under vaccine antibody selection had four unique mutations(H366Q and A322E in PB2 gene and P154A and A246Q in M gene). Passaged viruses N9L and N9T adapted by vaccine antibody selection had ten shared mutations,including those in NS gene(S81L,H85S),PB2 gene(I298Q,E526R),NP gene(L187G),PA gene(L336M),M gene(H23I),PB1 gene(T348A) and NP gene(G52A). The virus passaged without vaccine antibody selection had significantly higher infectivity to the chicken embryo than the parental virus(P<0.01),while the infectivity of the virus passaged with vaccine antibody selection was similar to that of the parental virus(P>0.05). The findings have important reference significance for studying the evolution of avian influenza virus under the pressure of vaccine selection and understanding the impact of vaccines on virus evolution.