1a. Objectives (from AD-416):
1. Determine vaccine efficacy following vaccination with inactivated Newcastle disease virus antigen vaccine against highly pathogenic Newcastle disease virus challenge. 2. Determine seroconversion against Newcastle disease virus (NDV) following vaccination of 4 week old specific pathogen free (SPF) chickens with inactivated NDV vaccines.
1b. Approach (from AD-416):
1. Viruses representative of circulating genotypes will be grown to high titers in eggs. 2. Amount of antigen to be used will be compared and standardized using a monoclonal antibody that recognizes a highly conserved epitope present in all viruses. 3. The antigen will be denatured using standard techniques and injected in 4 week SPF chickens to determine immune response and protection against NDV challenge. 4. Efficacy will be determined using high pathogenicity Newcastle disease virus in 4 week old SPF chicken with measurement of protection being prevention of morbidity and mortality, reduction in number of infected birds, and a decrease in the NDV-shed from respiratory and alimentary tracts. 5. Two antigens from genotype VI and VII will be compared to a mock vaccinated and to a standard vaccine based on a lentogenic virus and three different challenge viruses will be used (4x3 a total of 12 cages).
3. Progress Report:
This project is related to objective 3 of this in-house project: Develop vaccine strategies to effectively control Newcastle disease and stop disease outbreaks by developing vaccine platforms specifically designed to control low virulent and virulent Newcastle disease outbreaks. The objectives one through two of this agreement were fully meet and objective three is on going. New viruses were evaluated and the effect of homologous and heterologous vaccines determined. It was found that when the immune response is sufficiently elevated the use of homologous antigens improved the performance of vaccines, however if the antigens are not sufficient to achieve a high immune response the homologous vaccines cannot protect accordingly.