Section of Virology, Department of Medicine, Imperial College London, St. Mary's Campus, London, United Kingdom.
J Virol. 2013 Jan;87(1):384-94. doi: 10.1128/JVI.01633-12. Epub 2012 Oct 17.
Reassortant influenza viruses with combinations of avian, human, and/or swine genomic segments have been detected frequently in pigs. As a consequence, pigs have been accused of being a "mixing vessel" for influenza viruses. This implies that pig cells support transcription and replication of avian influenza viruses, in contrast to human cells, in which most avian influenza virus polymerases display limited activity. Although influenza virus polymerase activity has been studied in human and avian cells for many years by use of a minigenome assay, similar investigations in pig cells have not been reported. We developed the first minigenome assay for pig cells and compared the activities of polymerases of avian or human influenza virus origin in pig, human, and avian cells. We also investigated in pig cells the consequences of some known mammalian host range determinants that enhance influenza virus polymerase activity in human cells, such as PB2 mutations E627K, D701N, G590S/Q591R, and T271A. The two typical avian influenza virus polymerases used in this study were poorly active in pig cells, similar to what is seen in human cells, and mutations that adapt the avian influenza virus polymerase for human cells also increased activity in pig cells. In contrast, a different pattern was observed in avian cells. Finally, highly pathogenic avian influenza virus H5N1 polymerase activity was tested because this subtype has been reported to replicate only poorly in pigs. H5N1 polymerase was active in swine cells, suggesting that other barriers restrict these viruses from becoming endemic in pigs.
重组流感病毒具有禽、人、和/或猪基因组片段的组合，经常在猪中检测到。因此，猪被指责为流感病毒的“混合容器”。这意味着猪细胞支持禽源流感病毒的转录和复制，而不是人细胞，在人细胞中，大多数禽源流感病毒聚合酶显示出有限的活性。尽管多年来人们一直用人和禽细胞的小基因组测定法研究流感病毒聚合酶的活性，但在猪细胞中尚未报道类似的研究。我们开发了第一个猪细胞小基因组测定法，并比较了源自禽或人的流感病毒的聚合酶在猪、人、和禽细胞中的活性。我们还在猪细胞中研究了一些已知的增强流感病毒聚合酶在人细胞中活性的哺乳动物宿主范围决定因素的后果，例如 PB2 突变 E627K、D701N、G590S/Q591R 和 T271A。本研究中使用的两种典型的禽源流感病毒聚合酶在猪细胞中的活性很差，与在人细胞中的情况相似，使禽源流感病毒聚合酶适应人细胞的突变也增加了猪细胞中的活性。相比之下，在禽细胞中观察到不同的模式。最后，测试了高致病性禽流感病毒 H5N1 聚合酶的活性，因为据报道这种亚型在猪中复制很差。H5N1 聚合酶在猪细胞中具有活性，这表明其他障碍限制了这些病毒在猪中成为地方性流行。
