|Thomas, Colleen -|
|Pritchard, Nikki -|
|Rojo, Francisco -|
|Bublot, Michel -|
Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 26, 2010
Publication Date: May 12, 2010
Citation: Eggert, D.L., Thomas, C., Spackman, E., Pritchard, N., Rojo, F., Bublot, M., Swayne, D.E. 2010. Characterization and efficacy determination of commercially available Central American H5N2 avian influenza vaccines for poultry. Vaccine. 28:4609-4615. Interpretive Summary: A poultry vaccination program was implemented in Central America beginning in January 1995 to control low and high pathogenicity avian influenza. Yet despite the use of over 2 billion doses, low pathogenicity avian influenza remains endemic in some parts of Mexico. This study was conducted to determine if nine commercially available vaccines, including the original vaccine licensed in 1994 by Mexico were able to protect poultry from a 2003 low pathogenicity avian influenza virus isolated in Guatamala. We found only three vaccines afforded protection from low pathogenicity avian influenza and these three vaccines did not include the original Mexican licensed vaccine. Our results indicate an individual vaccine’s ability to protect poultry from avian influenza needs to be assessed periodically by testing with current field strains.
Technical Abstract: A poultry vaccination program was implemented in Central America beginning in January 1995 to control both H5N2 low (LPAI) and high pathogenicity avian influenza. This study was conducted to identify seed strain composition and the efficacy of nine commercially available H5 vaccines against challenge with H5N2 LPAI viruses isolated from Latin America in 2003. The original 1994 vaccine seed virus in commercial vaccines did not significantly reduce challenge virus shed titers. However, two seed strains, genetically more closely related to the challenge virus, did significantly reduce titers of challenge virus shed from respiratory tract. In addition, a live recombinant fowlpox virus vaccine containing a more distantly related Eurasian lineage H5 gene insert significantly reduced respiratory shedding 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 against current field strains in order to select efficacious vaccine seed strains.