Featured post

#Avian #Influenza #H7N9 in #China: Preventing the Next #SARS (@WHO, Apr. 2 ‘17)

  Title : #Avian #Influenza #H7N9 in #China: Preventing the Next #SARS. Subject : Avian Influenza, H7N9 subtype (Asian Lineage), poultry e...

30 Nov 2012

Molecular Characterization of the Predominant Influenza A(H1N1)pdm09 Virus in Mexico, December 2011–February 2012 (PLoS ONE, abstract, edited)

[Source: PLoS ONE, full text: (LINK). Abstract, edited.]

Molecular Characterization of the Predominant Influenza A(H1N1)pdm09 Virus in Mexico, December 2011–February 2012

Daniela de la Rosa-Zamboni1#, Joel A. Vázquez-Pérez1#, Santiago Ávila-Ríos1#, Ana Paola Carranco-Arenas1, Christopher E. Ormsby1, Craig A. Cummings2¤, Maribel Soto-Nava1, Víctor A. Hernández-Hernández1, Carmen O. Orozco-Sánchez1, Claudia Alvarado-de la Barrera1, Rogelio Pérez-Padilla1, Gustavo Reyes-Terán1*

1 Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico, 2 Life Technologies Corporation, Foster City, California, United States of America



When the A(H1N1)pdm09 pandemic influenza virus moved into the post-pandemic period, there was a worldwide predominance of the seasonal influenza A(H3N2) and B viruses. However, A(H1N1)pdm09 became the prevailing subtype in the 2011–2012 influenza season in Mexico and most of Central America. During this season, we collected nasopharyngeal swabs of individuals presenting with influenza-like illness at our institution in Mexico City. Samples were tested for seasonal A(H3N2) and B influenza viruses, as well as A(H1N1)pdm09 by real-time reverse transcription–polymerase chain reaction. Of 205 samples tested, 46% were positive to influenza, all of them A(H1N1)pdm09. The clinical characteristics of patients showed a similar pattern to the 2009 pandemic cases. Using next generation sequencing, we obtained whole genome sequences of viruses from 4 different patients, and in 8 additional viruses we performed partial Sanger sequencing of the HA segment. Non-synonymous changes found in the Mexican isolates with respect to the prototype isolate H1N1 (A/California/04/2009) included HA S69T, K163R and N260D unique to 2012 Mexican and North American isolates and located within or adjacent to HA antigenic sites; HA S143G, S185T, A197T and S203T previously reported in viruses from the 2010–2011 season, located within or adjacent to HA antigenic sites; and HA E374K located in a relevant site for membrane fusion. All Mexican isolates had an oseltamivir-sensitive genotype. Phylogenetic analysis with all 8 influenza gene segments showed that 2012 Mexican sequences formed a robust, distinct cluster. In all cases, 2012 Mexican sequences tended to group with 2010–2011 Asian and European sequences, but not with 2009 Mexican sequences, suggesting a possible recent common ancestor between these latter regions and the 2012 Mexican viruses. It remains to be defined if these viral changes represent an important antigenic drift that would enable viral immune evasion and/or affect influenza vaccine effectiveness.


Citation: de la Rosa-Zamboni D, Vázquez-Pérez JA, Ávila-Ríos S, Carranco-Arenas AP, Ormsby CE, et al. (2012) Molecular Characterization of the Predominant Influenza A(H1N1)pdm09 Virus in Mexico, December 2011–February 2012. PLoS ONE 7(11): e50116. doi:10.1371/journal.pone.0050116

Editor: Frederick C. C. Leung, University of Hong Kong, China

Received: July 13, 2012; Accepted: October 16, 2012; Published: November 29, 2012

Copyright: © 2012 de la Rosa-Zamboni et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: This work was supported by the Comisión de Equidad y Género de la Honorable Cámara de Diputados de la LXI Legislatura de México; Fundación México Vivo (; and a grant from the Instituto Nacional de Ciencia y Tecnología del Distrito Federal (ICyTDF 141849) to JAVP with a scholarship to COOS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: At the time of writing Craig A. Cummings was an employee at Life Technologies Corporation. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials. All other authors declare that they do not have any competing interests.

* E-mail:

# These authors contributed equally to this work.

¤Current address: Sequenta, Inc., South San Francisco, California, United States of America