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Humoral immune response of chickens possessing maternal antibodies and vaccinated under stress conditions with a bivalent live infectious bronchitis and Newcastle disease vaccine

Humoral immune response of chickens possessingmaternal antibodies and vaccinated under stress conditions with a bivalent live infectious bronchitis and Newcastle disease vaccine Background and purpose: Regarding the losses caused by infectious bronchitis (IB) and Newcastle disese (ND) viruses, poultry protection by vaccination is accepted as a common practice. The use of combined IBV/NDV vaccines reduces the cost of vaccination and diminishes the production losses caused by vaccination stress. The efficacy of the vaccination depends on numerous factors and they must be taken into account at the vaccination programme design. The aims of this study are the determination of the influence of the maternal immunity and accomodation under stress conditions on the hvmoral immune responses of the broilers vaccinated with a combined live IBV/NDV vaccine. Material and methods: One group of broilers, possesing maternal antibodies, was twice vaccinated with IBVINDV vaccine at the age of one day and 3 weeks, while another was vaccinated once at the age of 3 weeks. One day old chickens were vaccinated by coarse spray method. Chickens 3-weeek-old received vaccine through drinking water. All chickens were vaccinated against infectious bursal disease (IBD) at the age of 10 days. Chickens were housed under condions of higher population density and elevated ambiental temperature, and under norma rearing conditions. Commercially-available ELISA kits were used in order to determine the titers of antibodies against IBV, NDV and IBDV. Results: Vaccination with a live IBV/NDV vaccine carried out at the chicken age of one day had no influence on the levels of passive virus-neutralizing anti bodies. Furthermore, IBV vaccine administered at the 1st day of life did not generate sufficient humoral immunity until the slaughter. The vaccination and revaccination of 3-week-old chickens resulted in the development of high leveIs of specific antibodies. The IBDV vaccine administered at the age of 10 days ensured a lasting humoral immunity during the whole rearing cycle. Stress conditions had no significant influence on the humoral response against the vaccine viruses.

antibody ; chickens ; combined vaccine ; humoral immune response ; infectious bronchitis ; infedious bursal disease ; live vaccine ; Newcastle disease ; poultry

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