Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 2006
Publication Date: April 1, 2006
Citation: Swayne, D.E., Lee, C.W., Spackman, E. 2006. Inactivated North American and European H5N2 avian influenza virus vaccines protect chickens from Asian H5N1 high pathogenicity avian influenza virus. Avian Pathology. 35(2):141-146. Interpretive Summary: The deadly H5N1 high pathogenicity avian influenza (HPAI) virus has caused large death losses in birds within nine Asian countries/regions. Chickens vaccinated with two different H5N2 commercial AI vaccine strains were protected from a recent Asian H5N1 HPAI virus. The chickens were protected from illness and death, and the H5N1 virus grew in few birds. In addition, when the virus grew in vaccinated chickens, much less virus was produced than in non-vaccinated chickens. These data indicate that the currently available H5 vaccines will protect chickens against the Asian H5N1 HPAI virus should it enter the USA.
Technical Abstract: High pathogenicity (HP) avian influenza (AI) of the H5N1 subtype has caused an unprecedented epizootic in birds within nine Asian countries/regions since first reported in 1996. Vaccination has emerged as a tool for use in managing the infection in view of future eradication. This study was undertaken to determine if two divergent H5N2 commercial vaccine strains, one based on a European and the other a North American low pathogenicity AI virus, could protect chickens against a recent Asian H5N1 HPAI virus. The North American and European vaccine viruses had 84% and 91% deduced amino acid sequence similarity to the HA1 segment of haemagglutinin protein of Indonesia H5N1 HPAI challenge virus, respectively. Both vaccine strains provided complete protection from clinical signs and death. The vaccines reduced the number of chickens infected and shedding virus from the respiratory and intestinal tracts. In addition, the quantity of virus shed was reduced by 104-5 mean embryo infectious doses (EID50). The use of specific neuraminidase inhibition tests allowed identification of infected chickens within the vaccinated groups. These data indicate that the currently available H5 vaccines of European and North American lineages will protect chickens against the Asian H5N1 HPAI virus and reduce environmental contamination by the H5N1 HPAI virus. They will be an adjunct to biosecurity measures to reduce virus transmission.