1a.Objectives (from AD-416)
The objective of the grant is to better define the genetic and antigenic properties of currently circulating H1 subtype swine influenza viruses (SIV). The proposed work will be published and provide a reference for all future descriptions of H1 SIV.
1b.Approach (from AD-416)
Swine influenza viruses isolated from cases of swine respiratory disease outbreaks at the University of Minnesota Veterinary Diagnostic Laboratory (MVDL) during 2007-2008 will be selected based on representation from each of the current H1 genetic clusters using partial HA gene sequence. The isolates (approximately 12) will be transferred to USDA/ARS-NADC and USDA/APHIS-NVSL for the experimental work. The viruses will be propagated for use as antigen in the HI assay and for vaccine preparations. Additionally, the propagated viruses will be used for sequencing of the HA and NA genes. Inactivated virus preparations will be given to two pigs per isolate to produce immune-serum. Immune-sera will be tested with each of the virus antigens in all combinations in the HI assay. In addition, previously generated reference H1 anti-sera and virus will be included in the cross-HI assays (~11 virus isolates and 22 sera) . Geometric mean reciprocal titers will be calculated for each pair of sera, and comparisons will be made to identify greater than 4-fold differences in titers to evaluate sero-cross-reactivity between H1 isolates. Full length sequencing of the HA and NA genes will be conducted for each of the 10 new isolates. Sequences from viruses used to generate the previously evaluated immune-sera will be included as well as sequences in publicly available databases. The sequences will be analyzed and phylogenetic trees will be produced.
The objective of this agreement is to evaluate 12 recent H1 swine influenza virus (SIV) at the genetic and antigenic level for developing improved diagnostic reagents, vaccine candidates, and an improved understanding of the molecular epidemiology of SIV. Since June 1, 2008, the 12 isolates have been selected and received from University of Minnesota. The remaining animal and laboratory work is planned for early fiscal year 2009. This research relates to National Program 103 - Animal Health Action Plan Component 4. Respiratory Diseases.