PB2 and Hemagglutinin Mutations Are Major Determinants of Host Range and Virulence in Mouse-Adapted Influenza A Virus
PB2 and Hemagglutinin Mutations Are Major Determinants of Host Range and Virulence in Mouse-Adapted Influenza A Virus
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DOI：
10.1128/jvi.01187-10
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发表时间：
2010-10-01
影响因子：
5.4
通讯作者：
Brown, Earl G.
中科院分区：
文献类型：
--
作者：
Ping, Jihui;Dankar, Samar K.;Brown, Earl G.
人A型流感病毒A/Hong Kong/1/68（H3 N2）（HK-wt）在小鼠肺中连续传代，产生了一种小鼠适应性变体MA，具有9个突变，毒力高出10（3.8）倍。在这项研究中，我们证明了wB 2（D 701 N）和血凝素（HA）（G218 W在HA 1和T156 N在HA 2）基因的MA突变是最适应的遗传决定因素，增加小鼠模型的生长和毒力。在HK-wt骨架上表达每个突变的MA基因组区段的重组病毒显示出显著增加的疾病严重性，而只有小鼠适应的PB 2基因增加了毒力，如通过50%致死剂量（[LD 50] > 10（1.4）倍）所确定的。表达每个HK-wt基因组片段的重组MA病毒的匡威比较显示，HA基因导致的毒力降低最大（10（2）倍），M1、NS 1、NA和PB 1基因导致的毒力降低较小（10（0.3）-10（0.8）倍），PB 2和NP基因对LD 50的影响不可检测。然而，根据体重减轻和死亡时间的测量，HK PB 2基因确实减轻了MA感染。适应性突变在体内和体外的复制表现出病毒基因骨架和宿主范围效应。微型基因组转录测定显示，PB 1和PB 2突变增加聚合酶活性，并且PB 2 D 701 N突变与哺乳动物适应性PB 2 E627 K突变的效果相当。我们的研究结果表明，宿主范围和毒力是由多个基因控制的，PB 2和HA突变的主要作用。
Serial mouse lung passage of a human influenza A virus, A/Hong Kong/1/68 (H3N2) (HK-wt), produced a mouse-adapted variant, MA, with nine mutations that was >10(3.8)-fold more virulent. In this study, we demonstrate that MA mutations of the wB2 (D701N) and hemagglutinin (HA) (G218W in HA1 and T156N in HA2) genes were the most adaptive genetic determinants for increased growth and virulence in the mouse model. Recombinant viruses expressing each of the mutated MA genome segments on the HK-wt backbone showed significantly increased disease severity, whereas only the mouse-adapted PB2 gene increased virulence, as determined by the 50% lethal dose ([LD50] > 10(1.4)-fold). The converse comparisons of recombinant MA viruses expressing each of the HK-wt genome segments showed the greatest decrease in virulence due to the HA gene (10(2)-fold), with lesser decreases due to the M1, NS1, NA, and PB1 genes (10(0.3)- to 10(0.8)-fold), and undetectable effects on the LD50 for the PB2 and NP genes. The HK PB2 gene did, however, attenuate MA infection, as measured by weight loss and time to death. Replication of adaptive mutations in vivo and in vitro showed both viral gene backbone and host range effects. Minigenome transcription assays showed that PB1 and PB2 mutations increased polymerase activity and that the PB2 D701N mutation was comparable in effect to the mammalian adaptive PB2 E627K mutation. Our results demonstrate that host range and virulence are controlled by multiple genes, with major roles for mutations in PB2 and HA.