title: Genetic diversity of influenza A(H1N1)2009 virus circulating during the season 2010-2011 in Spain.
abstract: 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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors: National Influenza Centre-Madrid, Influenza and Respiratory Viruses Laboratory, Instituto de Salud Carlos III, Madrid, Spain. jledesmam@isciii.es
authors: Juan
authors: J
authors: Ledesma
authors: Francisco
authors: F
authors: Pozo
authors: Gabriel
authors: G
authors: Reina
authors: Miriam
authors: M
authors: Blasco
authors: Guadalupe
authors: G
authors: Rodríguez
authors: Milagrosa
authors: M
authors: Montes
authors: Isabel
authors: I
authors: López-Miragaya
authors: Carmen
authors: C
authors: Salvador
authors: Jordi
authors: J
authors: Reina
authors: Raúl
authors: R
authors: Ortíz de Lejarazu
authors: Pilar
authors: P
authors: Egido
authors: José
authors: J
authors: López Barba
authors: Concepción
authors: C
authors: Delgado
authors: María Teresa
authors: MT
authors: Cuevas
authors: Inmaculada
authors: I
authors: Casas
mesh_terms: D019943:Amino Acid Substitution; D000940:Antigenic Variation; D005814:Genes, Viral; D014644:Genetic Variation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D010802:Phylogeny; D011392:Proline / Q000378:metabolism; D012621:Seasons; D013030:Spain / Q000453:epidemiology
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D011392:Proline