Viral mRNA Export

The viral polymerase complex produces positive-sense viral mRNA with host-cell derived 5' methyl caps. Capped viral mRNAs are selectively exported from the host cell nucleus through a currently unclear mechanism that may rely on components of the host cell mRNA export machinery (Chen, 2000; Engelhardt, 2006). Polyadenylation of viral mRNA appears be required for influenza mRNA export (Poon, 2000). A coupling of viral mRNA export with cellular pre-mRNA processing complexes, recruited by phosphorylation of host RNA polymerase II C-terminal domain which interacts with the viral polymerase (Engelhardt, 2005), has been proposed as controlling the export of a subset (M1, HA, and NS1, but not NP) of viral mRNA from the nucleus (Amorim, 2007).

病毒多聚酶复合物生成带有宿主细胞衍生的5'甲基帽的正链病毒mRNA。带有帽结构的病毒mRNA通过一种目前尚不明确的机制被选择性地从宿主细胞核中输出，该机制可能依赖于宿主细胞mRNA输出机器的组成部分（Chen，2000；Engelhardt，2006）。病毒mRNA的聚腺苷酸化对于流感mRNA的输出似乎是必需的（Poon，2000）。一种将病毒mRNA的输出与由宿主RNA多聚酶II羧基端域磷酸化而招募的细胞前mRNA加工复合物耦合的机制，该羧基端域与病毒多聚酶相互作用（Engelhardt，2005），已被提出作为控制病毒mRNA（M1、HA和NS1，但非NP）子集从细胞核输出的调控因素（Amorim，2007）。