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 project is related to Objective 2 of this in-house project: 2. Development of improved Newcastle disease control strategies addressing issues important to virus transmission, vaccines and vaccination, diagnostics, or international trade, and Develop models to show vaccination is a viable method of controlling avian paramyxovirus outbreaks. One Newcastle disease virus (NDV) vaccine study was completed on Herpes Virus of Turkeys (HVT) vectored NDV vaccines to evaluate clinical disease and the amount of challenge virus shed from vaccinated birds. All of the swabs samples from this experiment were evaluated for the amount of virus shed using real time RT-PCR. Swabs from an additional study performed off site were received and evaluated for the amount of NDV challenge virus present. The data for both experiments is used to determine the best construction of the vectored vaccine and also the best promoter for the vaccine. There has been an improvement in protection over time from the first experiment when the collaboration first began to the fourth experiment, evaluated most recently.