EVALUATION OF RECOMBINANT HERPRESVIRUS-OF-TURKEYS VACCINE AGAINST AVIAN INFLUENZA H5N1
Exotic and Emerging Avian Viral Diseases Research Unit
2012 Annual Report
1a.Objectives (from AD-416):
1. Determine seroconversion against avian influenza following in ovo and day-of-age vaccination of specific pathogen free (SPF) and commercial chickens with recombinant herpesvirus of turkeys (HVT)-vectored avian influenza (AI) vaccine.
2 Determine vaccine efficacy following vaccination with recombinant HVT/AI vaccine against highly pathogenic avian influenza (HPAI) H5N1 challenge.
1b.Approach (from AD-416):
Avian influenza (AI) hemagglutinin (HA) gene from current H5 field viruses was cloned into a herpesvirus of turkeys (HVT) vaccine. The HVT-AI vaccines, expressing HA protein, will be injected in SPF and commercial poultry to determine immune response and protection against HPAI challenge. Efficacy will be determined using high pathogenicity AI chicken models with measurement of protection being prevention of morbidity and mortality, reduction in number of infected birds and a decrease in the AI-shed from respiratory and alimentary tracts.
This work refers to objective 4, using reverse genetics approaches for avian influenza and Newcastle Disease Virus, examine the role of individual viral genes in host gene response.
Vaccine protection of turkeys against H5N1 highly pathogenic avian influenza (HPAI). Turkeys are a susceptible species to morbidity and mortality associated with HPAI infection. Current vaccines and vaccination strategies are currently being developed to protect commercial poultry and decrease transmission of these viruses. The objective of this study is to evaluate the efficacy of recombinant avian influenza vaccines (H5 subtype) in turkeys against challenge with a H5N1 HPAI isolate. Following challenge with a lethal dose of H5N1 HPAI, ninety-eight percent of infected turkeys receiving the recombinant AI vaccine survived, whereas all sham vaccinated birds died. In addition, application of the recombinant vaccine reduced the incidence and amount of viral shedding. These results indicate this type of recombinant vaccine can be used as an aid during AI eradication efforts in turkey species.