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[Vaccination against Newcastle disease with variants and differentiation between post-vaccinal and post-infectious
V Jestin1, M Cherbonnel, G Bennejan
1CNEVA, Laboratoire central de recherche avicole et porcine, Ploufragan, France.
Abstract:
Three monoclonal antibody (anti-HN Mab 3115) resistant variants of the Newcastle disease virus (NDV) La Sota strain, were selected (a25, b23, a16); once cloned and shown by haemagglutination inhibition, ELISA and Western blot, not to bind to Mab 3115 they were used as experimental vaccines for chicken. The intracerebral pathogenicity index (ICPI) of a25 and b23 variants was low (0.2 and 0.0 respectively). Three to 4 weeks post-administration of alive variants or inactivated b23, respectively administered via eye drop and subcutaneously, the protection against a challenge was not different from that following La Sota vaccination. Antibody titers induced by a25 and b23, as measured by 2 ELISA blocking tests (the first employing a NDV specific Mab 2114, the second employing Mab 3115), were significantly lower (P less than 0.001) than post-challenge antibody titers. On the contrary, the difference between post-La Sota vaccination antibodies and post challenge antibodies was weak (P less than 0.02). Following 3 successive exposures by contact of chickens to live b23 variant, no variation in antibody titers was observed as measured by ELISA employing Mab 3115. This constituted a necessary criterion, but insufficient to test the stability of the b23 variant. At the same time, the latter exhibited poor ability to diffuse. Vaccination with these variants should be considered in differentiating post-vaccinal from post-infectious antibodies.
Insights
Newcastle disease virus (NDV) variants resistant to monoclonal antibody 3115 were evaluated as vaccines. These NDV variants provided protection comparable to the La Sota strain but induced lower antibody titers, aiding differentiation of vaccinated from infected birds.
Area of Science:
- Veterinary Virology
- Immunology
- Vaccinology
Background:
- Newcastle disease virus (NDV) is a significant avian pathogen.
- Developing effective NDV vaccines is crucial for poultry health.
- Differentiating between post-vaccinal and post-infectious antibodies is important for disease surveillance.
Purpose of the Study:
- To select and characterize monoclonal antibody-resistant NDV variants.
- To evaluate the efficacy of these variants as experimental vaccines in chickens.
- To assess the antibody responses induced by these variants for diagnostic purposes.
Main Methods:
- Selection and cloning of NDV La Sota strain variants resistant to anti-HN Mab 3115.
- Characterization using haemagglutination inhibition, ELISA, and Western blot.
- Vaccination of chickens with live or inactivated variants and challenge with virulent NDV.
- Measurement of antibody titers using ELISA blocking tests.
Main Results:
- Selected variants (a25, b23, a16) did not bind to Mab 3115.
- Variants a25 and b23 showed low intracerebral pathogenicity index (ICPI).
- Vaccination with variants provided protection comparable to La Sota strain.
- Variants induced significantly lower antibody titers than post-challenge titers.
- Variant b23 showed poor diffusion and stable antibody titers upon repeated exposure.
Conclusions:
- NDV variants resistant to Mab 3115 can serve as effective experimental vaccines.
- Lower antibody responses induced by these variants may aid in distinguishing vaccinated from infected birds.
- Further studies are needed to confirm the stability and efficacy of these variants for differentiating immune responses.