Collins Patrick J, Haire Lesley F, Lin Yi Pu, Liu Junfeng, Russell Rupert J, Walker Philip A, Skehel John J, Martin Stephen R, Hay Alan J, Gamblin Steven J
MRC-National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
Nature. 2008 Jun 26;453(7199):1258-61. doi: 10.1038/nature06956. Epub 2008 May 14.
The potential impact of pandemic influenza makes effective measures to limit the spread and morbidity of virus infection a public health priority. Antiviral drugs are seen as essential requirements for control of initial influenza outbreaks caused by a new virus, and in pre-pandemic plans there is a heavy reliance on drug stockpiles. The principal target for these drugs is a virus surface glycoprotein, neuraminidase, which facilitates the release of nascent virus and thus the spread of infection. Oseltamivir (Tamiflu) and zanamivir (Relenza) are two currently used neuraminidase inhibitors that were developed using knowledge of the enzyme structure. It has been proposed that the closer such inhibitors resemble the natural substrate, the less likely they are to select drug-resistant mutant viruses that retain viability. However, there have been reports of drug-resistant mutant selection in vitro and from infected humans. We report here the enzymatic properties and crystal structures of neuraminidase mutants from H5N1-infected patients that explain the molecular basis of resistance. Our results show that these mutants are resistant to oseltamivir but still strongly inhibited by zanamivir owing to an altered hydrophobic pocket in the active site of the enzyme required for oseltamivir binding. Together with recent reports of the viability and pathogenesis of H5N1 (ref. 7) and H1N1 (ref. 8) viruses with neuraminidases carrying these mutations, our results indicate that it would be prudent for pandemic stockpiles of oseltamivir to be augmented by additional antiviral drugs, including zanamivir.
大流行性流感的潜在影响使得采取有效措施限制病毒感染的传播和发病率成为公共卫生的优先事项。抗病毒药物被视为控制由新病毒引起的初始流感疫情的必要手段，并且在大流行前计划中严重依赖药物储备。这些药物的主要靶点是一种病毒表面糖蛋白——神经氨酸酶，它有助于新生病毒的释放，从而促进感染的传播。奥司他韦（达菲）和扎那米韦（瑞乐沙）是目前使用的两种神经氨酸酶抑制剂，它们是利用对该酶结构的了解而开发的。有人提出，这类抑制剂与天然底物越相似，就越不容易选择出具有生存能力的耐药突变病毒。然而，已有体外实验以及感染人类的病例报告出现耐药突变体的情况。我们在此报告了来自H5N1感染患者的神经氨酸酶突变体的酶学性质和晶体结构，这些结果解释了耐药性的分子基础。我们的结果表明，这些突变体对奥司他韦耐药，但由于奥司他韦结合所需的酶活性位点中疏水口袋发生了改变，它们仍受到扎那米韦的强烈抑制。结合最近关于携带这些突变的神经氨酸酶的H5N1（参考文献7）和H1N1（参考文献8）病毒的生存能力和致病性的报告，我们的结果表明，奥司他韦的大流行储备应增加包括扎那米韦在内的其他抗病毒药物，这将是审慎之举。
