Centre of Influenza Research, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
J Virol. 2012 Oct;86(19):10558-70. doi: 10.1128/JVI.00985-12. Epub 2012 Jul 18.
Limited antiviral compounds are available for the control of influenza, and the emergence of resistant variants would further narrow the options for defense. The H275Y neuraminidase (NA) mutation, which confers resistance to oseltamivir carboxylate, has been identified among the seasonal H1N1 and 2009 pandemic influenza viruses; however, those H275Y resistant variants demonstrated distinct epidemiological outcomes in humans. Specifically, dominance of the H275Y variant over the oseltamivir-sensitive viruses was only reported for a seasonal H1N1 variant during 2008-2009. Here, we systematically analyze the effect of the H275Y NA mutation on viral fitness and transmissibility of A(H1N1)pdm09 and seasonal H1N1 influenza viruses. The NA genes from A(H1N1)pdm09 A/California/04/09 (CA04), seasonal H1N1 A/New Caledonia/20/1999 (NewCal), and A/Brisbane/59/2007 (Brisbane) were individually introduced into the genetic background of CA04. The H275Y mutation led to reduced NA enzyme activity, an increased K(m) for 3'-sialylactose or 6'-sialylactose, and decreased infectivity in mucin-secreting human airway epithelial cells compared to the oseltamivir-sensitive wild-type counterparts. Attenuated pathogenicity in both RG-CA04(NA-H275Y) and RG-CA04 × Brisbane(NA-H275Y) viruses was observed in ferrets compared to RG-CA04 virus, although the transmissibility was minimally affected. In parallel experiments using recombinant Brisbane viruses differing by hemagglutinin and NA, comparable direct contact and respiratory droplet transmissibilities were observed among RG-NewCal(HA,NA), RG-NewCal(HA,NA-H275Y), RG-Brisbane(HA,NA-H275Y), and RG-NewCal(HA) × Brisbane(NA-H275Y) viruses. Our results demonstrate that, despite the H275Y mutation leading to a minor reduction in viral fitness, the transmission potentials of three different antigenic strains carrying this mutation were comparable in the naïve ferret model.
用于控制流感的抗病毒药物有限，而耐药变异的出现将进一步缩小防御选择。已在季节性 H1N1 和 2009 年大流行流感病毒中发现了神经氨酸酶（NA）突变 H275Y，该突变可导致奥司他韦羧酸盐耐药；然而，这些 H275Y 耐药变异在人类中表现出不同的流行病学结局。具体来说，只有在 2008-2009 年期间，季节性 H1N1 变异株中才报告了 H275Y 变异株对奥司他韦敏感病毒的优势。在这里，我们系统地分析了 H275Y NA 突变对 A(H1N1)pdm09 和季节性 H1N1 流感病毒的病毒适应性和传播性的影响。将 A(H1N1)pdm09 A/加利福尼亚/04/09（CA04）、季节性 H1N1 A/新喀里多尼亚/20/1999（NewCal）和 A/布里斯班/59/2007（Brisbane）的 NA 基因分别引入 CA04 的遗传背景中。与奥司他韦敏感的野生型相比，H275Y 突变导致 NA 酶活性降低、3'-唾液酸乳糖或 6'-唾液酸乳糖的 K(m)值增加，以及在黏液分泌的人呼吸道上皮细胞中的感染性降低。与 RG-CA04 病毒相比，在雪貂中观察到 RG-CA04(NA-H275Y)和 RG-CA04×Brisbane(NA-H275Y)病毒的致病性减弱，尽管传播能力受到的影响很小。在使用重组 Brisbane 病毒进行的平行实验中，差异仅在于血凝素和 NA，在 RG-NewCal(HA,NA)、RG-NewCal(HA,NA-H275Y)、RG-Brisbane(HA,NA-H275Y)和 RG-NewCal(HA)×Brisbane(NA-H275Y)病毒之间观察到了直接接触和呼吸道飞沫传播能力相当。我们的结果表明，尽管 H275Y 突变导致病毒适应性略有降低，但在天真雪貂模型中，携带该突变的三种不同抗原性菌株的传播潜力相当。
