Adam Dillon C, Scotch Matthew, MacIntyre C Raina
Biosecurity Program, The Kirby Institute, Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia.
Biodesign Center for Environmental Health Engineering, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA.
Viruses. 2019 Aug 27;11(9):791. doi: 10.3390/v11090791.
The clinical severity and observed case fatality ratio of influenza A/H1N1pdm09 in India, particularly in 2015 and 2017 far exceeds current global estimates. Reasons for these frequent and severe epidemic waves remain unclear. We used Bayesian phylodynamic methods to uncover possible genetic explanations for this, while also identifying the transmission dynamics of A/H1N1pdm09 between 2009 and 2017 to inform future public health interventions. We reveal a disproportionate selection at haemagglutinin residue positions associated with increased morbidity and mortality in India such as position 222 and clade 6B characteristic residues, relative to equivalent isolates circulating globally. We also identify for the first time, increased selection at position 186 as potentially explaining the severity of recent A/H1N1pdm09 epidemics in India. We reveal national routes of A/H1N1pdm09 transmission, identifying Maharashtra as the most important state for the spread throughout India, while quantifying climactic, ecological, and transport factors as drivers of within-country transmission. Together these results have important implications for future A/H1N1pdm09 surveillance and control within India, but also for epidemic and pandemic risk prediction around the world.
甲型H1N1pdm09流感在印度的临床严重程度及观察到的病死率，尤其是在2015年和2017年，远远超过目前的全球估计数。这些频繁且严重的疫情浪潮的原因仍不清楚。我们使用贝叶斯系统发育动力学方法来揭示其可能的遗传学解释，同时确定2009年至2017年期间甲型H1N1pdm09的传播动态，以为未来的公共卫生干预提供信息。我们发现，与印度发病率和死亡率增加相关的血凝素残基位置（如222位）以及6B分支特征性残基，相对于全球流行的等效分离株，存在不成比例的选择。我们还首次确定，186位的选择增加可能解释了印度近期甲型H1N1pdm09疫情的严重性。我们揭示了甲型H1N1pdm09在印度的传播途径，确定马哈拉施特拉邦是其在印度传播的最重要邦，同时量化气候、生态和交通因素作为国内传播的驱动因素。这些结果共同对印度未来的甲型H1N1pdm09监测和控制具有重要意义，对全球的疫情和大流行风险预测也具有重要意义。
