engleski

Protection of pullets and layers against Newcastle disease by an immune complex containing viral antigens

The immune response to a vaccination with a live lentogenic NDV strain and a booster with an immune complex (IC) was investigated. The insoluble IC was prepared at equivalence from NDV envelope glycoproteins, solubilized by a non-ionic detergent, and specific chicken IgY class antibodies. Different doses of IC were administered in a water suspension (WS) or a water-in-oil-emulsion (WOE). A single booster dose of only 5 µ ; ; g IC in WS i.v. administered to 8-week-old chicks, was sufficient to induce the protective level of anti-NDV antibodies as detected in haemagglutination inhibition (HI) test. Laying hens, boostered at the age of 32 weeks with a WS containing 10 µ ; ; g IC, had consistently high anti-NDV antibodies levels persisting for 10 weeks. Little change in the HI response and none in the efficacy of the protection, were observed after i.p. or i.v. inoculations of IC. An appropriate anti-NDV serological response of 22-week-old pullets, i.m. boostered with 10 µ ; ; g IC in the form of WOE, was also observed. The booster immunization with IC containing up to 4.2 µ ; ; g NDV envelope glycoproteins, generated high levels of anti-NDV antibodies and efficiently protected layers against experimental infection. An adequate level of antibody in egg yolks made embryos, as well as newly hatched chickens, protected against ND. The boosters and experimental infection did not affect the egg production.

poultry ; viral diseases ; vaccines ; immune response ; immunization

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