Phylogenetic analyses of influenza A (H1N1)pdm09 hemagglutinin gene during and after the pandemic event in Brazil.

摘要: Pandemic influenza A H1N1 [A(H1N1)pdm09] was first detected in Brazil May 2009, and spread extensively throughout the country causing a peak of infection during June to August 2009. Since then, it has continued to circulate with seasonal pattern, high rates morbidity mortality. Over this period, virus has continually evolved accumulation new mutations. In study we analyze phylogenetic relationship in collection 220 A(H1N1)pdm09 hemagglutinin (HA) gene sequences collected after the pandemic period (2009 2014) Brazil. addition, have looked for evidence viral polymorphisms associated with severe disease compared range variants vaccine strain (A/California/7/2009) used throughout period. The analyses revealed circulation at least eight genetic groups Two (G6- pdm G7-pdm) co-circulated pandemic showing an early pattern diversification with low distance from strain. Other groups, G5, G6 (including 6B, 6C 6D subgroups), and G7 were found subsequent epidemic seasons 2011 2014. These viruses exhibited more amino acid differences several substitutions antigenic sites. This is associated theoretical decrease efficacy. Furthermore, observed that presence of any polymorphism residue 222 HA significantly associated severe/fatal cases, reinforcing previous reports described as potential virulence marker. This provides information about some Brazil, follows up potential genetic markers allows infer if efficacy current against more recent strains may be reduced.