Origins of the 2009 H1N1 influenza pandemic in swine in Mexico
Icahn School of Medicine at Mount Sinai, United States; National Institutes of Health, United States; Laboratorio Avi-Mex, Mexico
DOI: http://dx.doi.org/10.7554/eLife.16777
Published June 28, 2016
Cite as eLife 2016;10.7554/eLife.16777
Abstract
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.
- Ignacio Mena
- Martha I Nelson
- Francisco Quezada-Monroy
- Jayeeta Dutta
- Refugio Cortes-Fern?ndez
- J Horacio Lara-Puente
- Felipa Castro-Peralta
- Luis F Cunha
- N?dia Sequeira Trov?o
- Bernardo Lozano-Dubernard
- Andrew Rambaut
- Harm van Bakel
- Adolfo Garc?a-Sastre

Icahn School of Medicine at Mount Sinai, United States; National Institutes of Health, United States; Laboratorio Avi-Mex, Mexico
DOI: http://dx.doi.org/10.7554/eLife.16777
Published June 28, 2016
Cite as eLife 2016;10.7554/eLife.16777
Abstract
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.