Discovery of Highly Potent Pinanamine-Based Inhibitors against Amantadine- and Oseltamivir-Resistant Influenza A Viruses

Influenza pandemic
is a constant major threat to public health caused by influenza A
viruses (IAVs). IAVs are subcategorized by the surface proteins hemagglutinin
(HA) and neuraminidase (NA), in which they are both essential targets
for drug discovery. While it is of great concern that NA inhibitor
oseltamivir resistant strains are frequently identified from human
or avian influenza virus, structural and functional characterization
of influenza HA has raised hopes for new antiviral therapies. In this
study, we explored a structure–activity relationship (SAR)
of pinanamine-based antivirals and discovered a potent inhibitor M090 against amantadine-resistant viruses, including the 2009
H1N1 pandemic strains, and oseltamivir-resistant viruses. Mechanism
of action studies, particularly hemolysis inhibition, indicated that M090 targets influenza HA and it occupied a highly conserved
pocket of the HA2 domain and inhibited virus-mediated membrane
fusion by “locking” the bending state of HA2 during the conformational rearrangement process. This work provides
new binding sites within the HA protein and indicates that this pocket
may be a promising target for broad-spectrum anti-influenza A drug
design and development.

由甲型流感病毒（influenza A viruses, IAVs）引发的流感大流行，始终是公共卫生领域的重大威胁。甲型流感病毒可根据其表面蛋白血凝素（hemagglutinin, HA）与神经氨酸酶（neuraminidase, NA）进行亚型分类，二者均为药物研发的关键靶点。尽管当前亟需关注的是，从人流感或禽流感病毒中频繁检出对神经氨酸酶抑制剂奥司他韦（oseltamivir）耐药的毒株，但对流感HA蛋白的结构与功能表征研究，为新型抗病毒疗法带来了希望。本研究针对基于蒎烷胺（pinanamine）的抗病毒药物开展构效关系（structure–activity relationship, SAR）研究，发现了一种强效抑制剂M090，其可对抗包括2009年H1N1大流行毒株在内的金刚烷胺（amantadine）耐药毒株，以及奥司他韦耐药毒株。作用机制研究（尤其是溶血抑制实验）结果表明，M090的作用靶点为流感HA蛋白，其可结合HA2结构域的高度保守口袋，并通过在构象重排过程中“锁定”HA2的弯曲状态，抑制病毒介导的膜融合。本研究为HA蛋白找到了全新的结合位点，同时表明该口袋可作为开发广谱抗甲型流感药物的极具潜力的靶点。