title: Genetic characterization of influenza virus circulating in Brazilian pigs during 2009 and 2010 reveals a high prevalence of the pandemic H1N1 subtype.
abstract: BACKGROUND
  Influenza A viruses circulating in pigs in Brazil are still not characterized, and only limited data are available about swine influenza epidemiology in the country. Therefore, we characterized the hemagglutinin (HA) and neuraminidase (NA) genes of influenza viruses isolated from Brazilian pigs. We also evaluated one case of probable swine-to-human transmission.
  
  
  METHODS
  Twenty influenza viruses isolated from pigs during 2009-2010 in five Brazilian states (Minas Gerais, Sao Paulo, Parana, Rio Grande do Sul, and Mato Grosso) were used. One human isolate, from a technician who became ill after visiting a swineherd going through a respiratory disease outbreak, was also used in the study. Phylogenetic analysis for the HA and NA genes and hemagglutinin amino acid sequence alignment were performed.
  
  
  RESULTS
  All isolates clustered with pandemic H1N1 2009 (pH1N1) viruses and appeared to have a common ancestor. Genetic diversity was higher in the HA than in the NA gene, and the amino acid substitution S203T in one of HA's antigenic sites was found in most of the samples. The human isolate was more related to swine isolates from the same herd visited by the technician than to other human isolates, suggesting swine-to-human transmission.
  
  
  CONCLUSIONS
  Our results show that pH1N1 was disseminated and the predominant subtype in Brazilian pigs in 2009-2010.
authors.affiliation: Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Daniela S
authors.initials: DS
authors.lastname: Rajão
authors.forename: Adrienny T R
authors.initials: AT
authors.lastname: Costa
authors.forename: Bruno S A F
authors.initials: BS
authors.lastname: Brasil
authors.forename: Helen L
authors.initials: HL
authors.lastname: Del Puerto
authors.forename: Fernanda G
authors.initials: FG
authors.lastname: Oliveira
authors.forename: Fabiana
authors.initials: F
authors.lastname: Alves
authors.forename: Gissandra F
authors.initials: GF
authors.lastname: Braz
authors.forename: Jenner K P
authors.initials: JK
authors.lastname: Reis
authors.forename: Roberto M C
authors.initials: RM
authors.lastname: Guedes
authors.forename: Zélia I P
authors.initials: ZI
authors.lastname: Lobato
authors.forename: Rômulo C
authors.initials: RC
authors.lastname: Leite
mesh_terms: D000818:Animals; D001938:Brazil / Q000453:epidemiology; D014644:Genetic Variation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D009980:Influenza A virus / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000235:genetics; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000821:virology*
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D009439:Neuraminidase
keywords: Genetic characterization; hemagglutinin; influenza A virus; pandemic; swine