ANTIGENIC, MOLECULAR, AND PATHOGENESIS ASSESSMENT OF SWINE INFLUENZA VIRUS (SIV) ISOLATES
2009 Annual Report
1a.Objectives (from AD-416)
Evaluate swine influenza virus (SIV) isolates through in vivo challenge and transmission studies, antigenic characterization with in-house reference sera, and molecular analysis.
1b.Approach (from AD-416)
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.
2)Novel gene introduction;.
3)Novel antigenic properties; or.
4)Unusual clinical presentation.
A post doctoral research associate was recruited and hired during year 1 of the agreement. A series of in vivo challenge and transmission studies in the swine host have been conducted with 2 isolates of 2009 pandemic H1N1 as outlined in the agreement with the Centers for Disease Control. Pigs were shown to be susceptible to infection; however the infection was demonstrated to be limited to the respiratory tract. Antigenic characterization was conducted between the pandemic H1N1 and the swine anti-H1 reference panel, with the results suggesting U.S. swine would be susceptible to outbreaks with the pandemic H1N1. Reports have been generated and posted on the ARS website. The implementation of the USDA-APHIS surveillance program was delayed, and no SIV isolates have been identified for characterization at NADC through this mechanism.