Start Date: Sep 01, 2008
End Date: Jan 31, 2012
The ARS' National Animal Disease Center (NADC) will support the proposed USDA-APHIS swine influenza surveillance program by providing additional characterization of emerging swine influenza virus (SIV) isolates identified through the surveillance program. The SIV isolates will be evaluated through in vivo challenge and transmission studies, antigenic characterization with in-house reference sera, and molecular analysis. Molecular analysis may include follow-up sequencing, nucleic acid and amino acid sequence comparisons, as well as computation of evolutionary relationships with reference sequences to construct phylogenetic trees. The in vivo studies will aid in identifying viruses with increased virulence, increased transmissibility, or other phenotypic properties. The molecular analyses will aid in identifying viruses with novel genetic make-up and allow a better understanding of the evolution and epidemiology of whole virus genomes. In addition to the NALN submission criteria, the NADC criteria shall be 1) Novel subtype; 2) Novel gene introduction; 3) Novel antigenic properties; or 4) Unusual clinical presentation. Groups of pigs will be inoculated with the appropriate influenza virus strains and doses (to be determined) by the intratracheal or intranasal route. Subsets of animals at selected time points following challenge will be euthanized to determine virus load in the respiratory tract whereas the remaining animals will be further studied to determine the duration of virus shedding and transmission to naive animals introduced a few days after challenge inoculation. Clinical, virologic, and serologic monitoring will be used to assess the outcomes of infection with different viruses to ascertain their potential threat to animal and human health.