title: Distribution of antibodies against influenza virus in pigs from farrow-to-finish farms in Minas Gerais state, Brazil.
abstract: BACKGROUND
  Swine influenza virus (SIV) is the cause of an acute respiratory disease that affects swine worldwide. In Brazil, SIV has been identified in pigs since 1978. After the emergence of pandemic H1N1 in 2009 (H1N1pdm09), few studies reported the presence of influenza virus in Brazilian herds.
  
  
  OBJECTIVE
  The objective of this study was to evaluate the serological profile for influenza virus in farrow-to-finish pig farms in Minas Gerais state, Brazil.
  
  
  METHODS
  Thirty farms with no SIV vaccination history were selected from the four larger pig production areas in Minas Gerais state (Zona da Mata, Triângulo Mineiro/Alto Paranaíba, South/Southwest and the Belo Horizonte metropolitan area). At each farm, blood samples were randomly collected from 20 animals in each production cycle category: breeding animals (sows and gilts), farrowing crate (2-3 weeks), nursery (4-7 weeks), grower pigs (8-14 weeks), and finishing pigs (15-16 weeks), with 100 samples per farm and a total of 3000 animals in this study. The samples were tested for hemagglutination inhibition activity against H1N1 pandemic strain (A/swine/Brazil/11/2009) and H3N2 SIV (A/swine/Iowa/8548-2/98) reference strain.
  
  
  RESULTS
  The percentages of seropositive animals for H1N1pdm09 and H3N2 were 26.23% and 1.57%, respectively, and the percentages of seropositive herds for both viruses were 96.6% and 13.2%, respectively.
  
  
  CONCLUSIONS
  The serological profiles differed for both viruses and among the studied areas, suggesting a high variety of virus circulation around the state, as well as the presence of seronegative animals susceptible to influenza infection and, consequently, new respiratory disease outbreaks.
authors: Laboratório de Pesquisa em Virologia Animal, Departamento de Medicina Veterinária Preventiva, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors: Alessandra S
authors: AS
authors: Dias
authors: Érica A
authors: ÉA
authors: Costa
authors: Daniela S
authors: DS
authors: Rajão
authors: Roberto M C
authors: RM
authors: Guedes
authors: Janice R
authors: JR
authors: Ciacci Zanella
authors: Zélia I P
authors: ZI
authors: Lobato
mesh_terms: D000383:Agriculture; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D001938:Brazil; D006385:Hemagglutination Inhibition Tests; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology*; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D016036:Seroepidemiologic Studies; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000517:prevention & control / Q000821:virology
chemical_list: D000914:Antibodies, Viral
keywords: Antibodies; Brazil; H3N2; pandemic H1N1; serological profile; swine influenza
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