Abstract：
Host restriction limits the emergence of novel pandemic strains from the influenza A virus avian reservoir. For efficient replication in mammalian cells, the avian influenza RNA-dependent RNA polymerase must adapt to use human orthologues of the host factor ANP32, which lack a 33-amino-acid insertion relative to avian ANP32A. Here, we find that influenza polymerase requires ANP32 proteins to support both steps of genome replication: cRNA and vRNA synthesis. However, avian strains are only restricted in vRNA synthesis in human cells. Therefore, avian influenza polymerase can use human ANP32 orthologues to support cRNA synthesis, without acquiring mammalian adaptations. This implies a fundamental difference in the mechanism by which ANP32 proteins support cRNA versus vRNA synthesis. IMPORTANCE To infect humans and cause a pandemic, avian influenza must first adapt to use human versions of the proteins the virus hijacks for replication, instead of the avian orthologues found in bird cells. One critical host protein is ANP32. Understanding the details of how host proteins such as ANP32 support viral activity may allow the design of new antiviral strategies that disrupt these interactions. Here, we use cells that lack ANP32 to unambiguously demonstrate ANP32 is needed for both steps of influenza genome replication. Unexpectedly, however, we found that avian influenza can use human ANP32 proteins for the first step of replication, to copy a complementary strand, without adaptation but can only utilize avian ANP32 for the second step of replication that generates new genomes. This suggests ANP32 may have a distinct role in supporting the second step of replication, and it is this activity that is specifically blocked when avian influenza infects human cells.
摘要：
宿主限制限制了甲型流感病毒禽库中新型大流行毒株的出现。为了在哺乳动物细胞中有效复制，禽流感RNA依赖性RNA聚合酶必须适应使用宿主因子ANP32的人类直系同源物,相对于禽类ANP32A,该因子缺乏33个氨基酸的插入.这里,我们发现,流感聚合酶需要ANP32蛋白来支持基因组复制的两个步骤:cRNA和vRNA合成.然而,禽类菌株仅在人细胞中的vRNA合成方面受到限制。因此,禽流感聚合酶可以使用人类ANP32直系同源物支持cRNA合成，没有获得哺乳动物的适应。这意味着ANP32蛋白支持cRNA与vRNA合成的机制存在根本差异。重要性感染人类并引起大流行，禽流感必须首先适应使用病毒劫持的人类版本的蛋白质进行复制，而不是在鸟类细胞中发现的鸟类直系同源物。一种关键的宿主蛋白是ANP32。了解宿主蛋白如ANP32如何支持病毒活性的细节可能允许设计破坏这些相互作用的新的抗病毒策略。这里,我们使用缺乏ANP32的细胞明确证明了流感基因组复制的两个步骤都需要ANP32.出乎意料的是,然而,我们发现禽流感可以利用人类ANP32蛋白进行复制的第一步，复制互补链，不适应，但只能利用禽类ANP32进行产生新基因组的第二步复制。这表明ANP32在支持复制的第二步中可能具有独特的作用，当禽流感感染人类细胞时，这种活动被特别阻断。
