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.
3. Progress Report
The project is related to objective 1 of the in-house project: Characterize mucosal immunity induced by natural infection and vaccination with both high and low pathogenicity avian influenza viruses (AIV) to identify innate and adaptive immune indicators of protection. Vaccines against avian influenza (AI) are valuable in the prevention and control of the disease and can be used in eradication strategies. A herpesvirus of turkeys (HVT) recombinant-vectored avian influenza vaccine with an AI H5 gene insert (rHVT/AI-H5) was tested in specific-pathogen-free chickens (SPF) against H5N1 high pathogenicity avian influenza(HPAI) (A/Whooper Swan\Mongolia\244\05). The vaccine was given by subcutaneous route (in the neck). After challenge, efficacy was evaluated by the presence or absence of clinical signs or mortality due to AI, and shedding of the challenge virus. Following direct challenge, SPF Leghorn chicks immunized with rHVT/AI-H5 displayed significant protection against direct challenge with H5N1 HPAI. No clinical signs of disease were observed in any vaccinated birds. In contrast all sham-vaccinated birds succumbed to challenge. Taken together, these data suggest that these recombinant-vectored vaccines expressing the hemagglutinin (HA) are effective against at protecting chickens against HPAI. MONITORING: The Authorized Departmental Officer's Designated Representative had regular email and telephone conversations with the cooperators at CEVA Biomune on research progress.