title: Experimental transmission of avian-like swine H1N1 influenza virus between immunologically naïve and vaccinated pigs.
abstract: BACKGROUND
  Infection of pigs with swine influenza has been studied experimentally and in the field; however, little information is available on the natural transmission of this virus in pigs. Two studies in an experimental transmission model are presented here, one in immunologically naïve and one in a combination of vaccinated and naïve pigs.
  
  
  OBJECTIVE
  To investigate the transmission of a recent 'avian-like' swine H1N1 influenza virus in naive piglets, to assess the antibody response to a commercially available vaccine and to determine the efficiency of transmission in pigs after vaccination.
  
  
  METHODS
  Transmission chains were initiated by intranasal challenge of two immunologically naïve pigs. Animals were monitored daily for clinical signs and virus shedding. Pairs of pigs were sequentially co-housed, and once virus was detected in recipients, prior donors were removed. In the vaccination study, piglets were vaccinated and circulating antibody levels were monitored by haemagglutination inhibition assay. To study transmission in vaccinates, a pair of infected immunologically naïve animals was co-housed with vaccinated recipient pigs and further pairs of vaccinates were added sequentially as above. The chain was completed by the addition of naive pigs.
  
  
  CONCLUSIONS
  Transmission of the H1N1 virus was achieved through a chain of six pairs of naïve piglets and through four pairs of vaccinated animals. Transmission occurred with minimal clinical signs and, in vaccinates, at antibody levels higher than previously reported to protect against infection.
authors.affiliation: Animal Health Trust, Kentford, Newmarket, Suffolk, UK.
authors.forename: Lucy E
authors.initials: LE
authors.lastname: Lloyd
authors.forename: Magdalena
authors.initials: M
authors.lastname: Jonczyk
authors.forename: Carley M
authors.initials: CM
authors.lastname: Jervis
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Flack
authors.forename: John
authors.initials: J
authors.lastname: Lyall
authors.forename: Alasdair
authors.initials: A
authors.lastname: Foote
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Mumford
authors.forename: Ian H
authors.initials: IH
authors.lastname: Brown
authors.forename: James L
authors.initials: JL
authors.lastname: Wood
authors.forename: Debra M
authors.initials: DM
authors.lastname: Elton
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification / Q000502:physiology; D007252:Influenza Vaccines; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000517:prevention & control / Q000635:transmission* / Q000821:virology; D014611:Vaccination; D017201:Virus Shedding
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines