Kashiwagi Takahito, Hara Koyu, Nakazono Yoko, Uemura Yusaku, Imamura Yoshihiro, Hamada Nobuyuki, Watanabe Hiroshi
Department of Infection Control and Prevention, Kurume University School of Medicine, Fukuoka, Japan.
PLoS One. 2014 Dec 2;9(12):e114502. doi: 10.1371/journal.pone.0114502. eCollection 2014.
Influenza A virus has a RNA-dependent RNA polymerase (RdRp) that is composed of three subunits (PB1, PB2 and PA subunit), which assemble with nucleoproteins (NP) and a viral RNA (vRNA) to form a RNP complex in the host nucleus. Recently, we demonstrated that the combination of influenza ribonucleoprotein (RNP) components is important for both its assembly and activity. Therefore, we questioned whether the inhibition of the RNP combination via an incompatible component in the RNP complex could become a methodology for an anti-influenza drug.
METHODOLOGY/PRINCIPAL FINDINGS: We found that a H5N1 PB2 subunit efficiently inhibits H1N1 RNP assembly and activity. Moreover, we determined the domains and important amino acids on the N-terminus of the PB2 subunit that are required for a strong inhibitory effect. The NP binding site of the PB2 subunit is important for the inhibition of RNP activity by another strain. A plaque assay also confirmed that a fragment of the PB2 subunit could inhibit viral replication.
CONCLUSIONS/SIGNIFICANCE: Our results suggest that the N-terminal fragment of a PB2 subunit becomes an inhibitor that targets influenza RNP activity that is different from that targeted by current drugs such as M2 and NA inhibitors.
甲型流感病毒具有一种由三个亚基（PB1、PB2和PA亚基）组成的RNA依赖性RNA聚合酶（RdRp），它与核蛋白（NP）和病毒RNA（vRNA）组装在一起，在宿主细胞核中形成核糖核蛋白（RNP）复合体。最近，我们证明流感核糖核蛋白（RNP）组分的组合对其组装和活性都很重要。因此，我们质疑通过RNP复合体中不相容的组分抑制RNP组合是否能成为一种抗流感药物的方法。
方法/主要发现：我们发现H5N1 PB2亚基能有效抑制H1N1 RNP的组装和活性。此外，我们确定了PB2亚基N端上产生强抑制作用所需的结构域和重要氨基酸。PB2亚基的NP结合位点对于另一毒株抑制RNP活性很重要。蚀斑试验也证实PB2亚基的一个片段可以抑制病毒复制。
结论/意义：我们的结果表明，PB2亚基的N端片段成为一种靶向流感RNP活性的抑制剂，其作用靶点不同于当前药物如M2和NA抑制剂的作用靶点。
