Background: Genetic diversity of influenza A(H1N1)2009 viruses has been reported since the pandemic virus emerged in April 2009. Different genetic clades have been identified and defined based on amino acid substitutions found in the haemagglutinin (HA) protein sequences. In Spain, circulating influenza viruses are monitored each season by the regional laboratories enrolled in the Spanish Influenza Surveillance System (SISS). The analysis of the HA gene sequence helps to detect the genetic diversity and viral evolution. Objectives: To perform an analysis of the genetic diversity of influenza A(H1N1)2009 viruses circulating in Spain during the season 2010-2011 based on analysis of the HA sequence gene. Study design: Phylogenetic analysis based on the HA1 subunit of the haemagglutinin gene was carried out on 220 influenza A(H1N1)2009 viruses circulating during the season 2010-2011. Results: Six different genetic groups were identified among circulating A(H1N1)2009 viruses, five of them were previously reported during season 2010-2011. A new group, characterized by E172K and K308E changes and a proline at position 83, was observed in 12.27% of the Spanish viruses. Conclusion: Co-circulation of six different genetic groups of influenza A(H1N1)2009 viruses was identified in Spain during the season 2010-2011. Nevertheless, at this stage, none of the groups identified to date have resulted in significant antigenic changes according to data collected by World Health Organization Collaborating Centres for influenza surveillance.
Bibliographical noteFunding Information:
We would like to acknowledge all members of the Spanish Influenza Surveillance System for the contribution in this study. The authors acknowledge technical assistance from Ana Calderón, Nieves Cruz, Mónica Gónzalez-Esguevillas, Manuela Lopez-Valero, Mar Molinero, Silvia Moreno and Noelia Reyes in the National Influenza Centre-Madrid. This study was supported by grant MPY-1440/09 (Spanish Ministry of Science and Innovation), by grant between the Institute of Health Carlos III and the Spanish Ministry of Health for the surveillance of influenza viruses circulating in Spain, DGEG-1304/08-TS-13-B, and by grant PS09/00246 (Fondo de Investigaciones Sanitarias, ISCIII).
This study was supported by grant PS09/00246 ( Fondo de Invesitgaciones Sanitarias, Spanish Ministry of Health and Social Policy ), by grant MPY-1440/09 ( Spanish Ministry of Science and Innovation ), an agreement signed between the Institute of Health Carlos III and the Spanish Ministry of Health and Social Policy for the surveillance of influenza viruses circulating in Spain, DGEG-1304/08-TS-13-B.
- Influenza A(H1N1)2009