Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2010
Publication Date: N/A
Technical Abstract: H5N2 low pathogenicity avian influenza (LPAI) was first identified in Mexican poultry during May 1994. A vaccination program was implemented, but after 14 years and 2 billion doses, H5N2 LPAI is still present in parts of Mexico and has spread to El Salvador, Guatemala, Dominican Republic, and Haiti. Seed strains were identified from nine commercially available H5 vaccines and efficacy studies were carried out using one of two challenge H5N2 LPAI viruses isolated from Latin America in 2003. Six of the vaccines failed to significantly reduce virus shed titers. Two seed strains significantly reduced titers of virus shed from respiratory tract and a live recombinant fowlpox virus vaccine significantly reduced oral titers as compared to sham vaccinates. These results demonstrate the feasibility of identifying vaccine seed strains in commercial finished products for regulatory verification and the need for periodic challenge testing with current field viruses to confirm efficacy of vaccine seed strains.