Data from: Origins of the 2009 H1N1 influenza pandemic in swine in Mexico

Asia is considered an important source of influenza A virus (IAV) pandemics, owing to large, diverse viral reservoirs in poultry and swine. However, the zoonotic origins of the 2009 A/H1N1 influenza pandemic virus (pdmH1N1) remain unclear, due to conflicting evidence from swine and humans. There is strong evidence that the first human outbreak of pdmH1N1 occurred in Mexico in early 2009. However, no related swine viruses have been detected in Mexico or any part of the Americas, and to date the most closely related ancestor viruses were identified in Asian swine. Here, we use 58 new whole-genome sequences from IAVs collected in Mexican swine to establish that the swine virus responsible for the 2009 pandemic evolved in central Mexico. This finding highlights how the 2009 pandemic arose from a region not considered a pandemic risk, owing to an expansion of IAV diversity in swine resulting from long-distance live swine trade.

由于家禽与猪群中存在规模庞大、种类多样的病毒储存库，亚洲被视为甲型流感病毒（influenza A virus, IAV）大流行的重要源头。然而，受猪源与人类来源的证据冲突影响，2009年A/H1N1流感大流行病毒（pdmH1N1）的人畜共患起源始终未能明确。已有充分证据显示，pdmH1N1的首例人类病例暴发于2009年初的墨西哥。但截至目前，墨西哥乃至美洲全境均未检出与之相关的猪源病毒，而亲缘关系最近的祖先毒株均在亚洲猪群中被发现。本研究通过新获取的58条墨西哥猪源甲型流感病毒全基因组序列，证实引发2009年流感大流行的猪源病毒演化自墨西哥中部地区。这一发现凸显了2009年大流行如何起源于一个此前未被视为大流行风险的区域——该区域因长距离活猪贸易导致猪群中甲型流感病毒多样性显著扩增，最终催生了此次全球大流行。