Division of Virology, Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, 262 Danny Thomas Place, Memphis, TN 38105-3678, USA.
Arch Virol. 2010 Jun;155(6):925-34. doi: 10.1007/s00705-010-0666-4. Epub 2010 Apr 11.
Despite reports that the PB1-F2 protein contributes to influenza virus pathogenicity in the mouse model, little is known about its significance in avian hosts. In our previous study, the A/Vietnam/1203/04 (H5N1) wild-type virus (wtVN1203) was more lethal to mallard ducks than a reverse genetics (rg)-derived VN1203. In search of potential viral factors responsible for this discrepancy, we found that synonymous mutations (SMs) had been inadvertently introduced into three genes of the rgVN1203 (rgVN1203/SM-3). Of 11 SMs in the PB1 gene, three resided in the PB1-F2 open reading frame, caused amino acid (aa) substitutions in the PB1-F2 protein, and reduced virus lethality in mallard ducks. The wtVN1203 and recombinant viruses with repairs to these three aa's (rgVN1203/R-PB1-F2) or with repairs to all 11 SMs (rgVN1203/R-PB1) were significantly more pathogenic than rgVN1203/SM-3. In cultured cells, repairing three mutations in PB1-F2 increased viral polymerase activity and expression levels of viral RNA.
尽管有报道称 PB1-F2 蛋白有助于流感病毒在小鼠模型中的致病性，但关于其在禽类宿主中的意义知之甚少。在我们之前的研究中，与反向遗传学（rg）衍生的 VN1203 相比，A/Vietnam/1203/04（H5N1）野生型病毒（wtVN1203）对绿头鸭更具致死性。为了寻找导致这种差异的潜在病毒因素，我们发现三个基因中的同义突变（SMs）已意外地引入到 rgVN1203 中（rgVN1203/SM-3）。在 PB1 基因的 11 个 SM 中，有 3 个位于 PB1-F2 开放阅读框中，导致 PB1-F2 蛋白中的氨基酸（aa）取代，并降低了绿头鸭中的病毒致死率。wtVN1203 和具有这三个 aa 修复的重组病毒（rgVN1203/R-PB1-F2）或具有所有 11 个 SM 修复的重组病毒（rgVN1203/R-PB1）比 rgVN1203/SM-3 具有更高的致病性。在培养的细胞中，修复 PB1-F2 中的三个突变增加了病毒聚合酶活性和病毒 RNA 的表达水平。
