Develop and evaluate the use of partial NS1 deleted attenuated viruses as potential vaccines for the control of avian influenza. Several approaches for vaccination including in ovo vaccination will be examined. The pathogenicity and risk of transmission between vaccinated and non-vaccinated birds will be evaluated. Also, select avian influenza viruses will be used to infect chickens, ducks, and turkeys to biologically compare these viruses in different hosts, and compare the biological information with their genetic information.
APPROACH: Using reverse genetics techniques and classical reassortment techniques, influenza viruses will be prepared that have specific deletions in the the NS gene that result in viruses with truncated NS1 proteins. These viruses are anticipated to be attenuated when inoculated into older chicken embryos or chickens. These viruses should still grow to high titer in younger chicken embryos. These viruses will be evaluated for in ovo vaccination of 18 day old embryos and young chicks for ability to produce a protective immune response as measured by challenge experiments. Additionally, other avian influenza viruses will be inoculated in to chickens, ducks, and turkeys for biological characterization.