1a.Objectives (from AD-416)
1. Evaluate antibody response induced by different Newcastle Disease virus (NDV) vaccine candidates expressing various gene inserts.
2. Evaluate efficacy of new NDV vaccine candidates against clinical disease and shedding after challenge with various velogenic NDV isolates.
3. Test different vaccination protocols for specific pathogen free (SPF) and commercial poultry to maximize NDV vaccine efficacies.
4. Share NDV challenge strains and reagents.
1b.Approach (from AD-416)
Different alternative Newcastle disease (ND) vaccines based on vector, reverse genetics or expression systems technologies will be generated and controlled for NDV gene expression by the Cooperator. Vaccines will be tested for immunogenicity and efficacy against different epidemiologically relevant NDV isolates. Protection will be evaluated in SPF and commercial chickens by prevention of illness and death, increasing resistance to infection, reduction in number of infected birds, decrease in the amount of challenge virus shed from respiratory and alimentary tracts, and reduction of transmission to contact birds. Different vaccine candidates will be associated in prime-boost immunization schemes to optimize immunity and protection.
This research is related to inhouse objective 2: Development of improved Newcastle disease control strategies addressing issues important to virus transmission, vaccines and vaccination, diagnostics, or international trade. Develop models to show vaccination is a viable method of controlling avian paramyxovirus outbreaks.
Two Newcastle disease virus (NDV) vaccine studies have been completed. The first vaccine study used plasmids (deoxyribonucleic acid [DNA] vaccines) with NDV genes inserted into them. Some of the NDV genes were the same as the challenge virus used, and others were different. Traditional inactivated and live NDV vaccines were used for a comparison. The serology is complete, but not very useful, due to lack of hemagglutination because a whole virus or hemagglutinin-neuraminidase was not inserted. The swabs from the first experiment are about 45% complete. The second experiment used NDV vaccines made from herpes virus of turkeys (HVT) as the vector in addition to one fowl-pox (FP) vectored vaccine. The mortality data suggests that there is one valid candidate for a possible HVT vaccine and that the FP vectored vaccine performed the best. Next studies: A third experiment will be planned for later this year.