Enhanced infectivity of H5N1 highly pathogenic avian influenza (HPAI) virus in pig ex vivo respiratory tract organ cultures following adaptation by in vitro passage.

Pigs are thought to play a role in the adaptation of avian influenza (AI) viruses to mammalian hosts. To better understand this mechanism and to identify key mutations two highly pathogenic AI (HPAI) viruses (H5N1 and H7N7) were grown in pig cells, To mimic the pressure of an immune response, these viruses were grown in the presence of antiserum to the homologous virus or porcine IFN-γ. Mutations were identified in both viruses grown in vitro in the presence and absence of antisera or IFN-γ and included the PB2 mutations, E627K or 627E,D701N, described previously as requirements for the adaptation of AI viruses to mammalian species.

Failure to infect pigs co-housed with ducks or chickens infected experimentally with A/turkey/Turkey/1/2005 (H5N1) highly pathogenic avian influenza virus.

To simulate a field situation in which pigs are in close contact with poultry and thus provide a potential mixing vessel for avian, swine and human influenza viruses, uninfected pigs were placed in contact with Pekin ducks or chickens infected with a H5N1 highly pathogenic avian influenza (HPAI) virus. To sustain prolonged exposure, newly inoculated birds were added at regular intervals. Although influenza virus was detected in birds and environmental samples, 14 days exposure to infected birds failed to produce evidence of infection in the pigs.

The infectivity of pandemic 2009 H1N1 and avian influenza viruses for pigs: an assessment by ex vivo respiratory tract organ culture.

Background: Pigs are thought to act as intermediate hosts in the ecology of influenza viruses of both avian and human origin. The recent development of procedures for pig ex vivo respiratory organ explants has provided new tools for the assessment of influenza virus infection in pigs.

Objectives: To use pig ex vivo organ explants to assess the susceptibility of pigs to infection with contemporary viruses, for which there is evidence of human infection and that are thought to pose the greatest threat to pig and human populations.