Genera Inc., part of Dechra Pharmaceuticals PLC, Svetonedeljska cesta, Croatia
- 1. GD Animal Health, Arnsbergstraat 7, The Netherlands
- 2. Genera Inc., part of Dechra Pharmaceuticals PLC, Svetonedeljska cesta, Croatia
Abstract
Infectious bronchitis (IB) is a highly contagious viral disease of chickens, resulting in animal discomfort and economic damage caused by production loss and instalment of interventions. Protection against IB is normally provided in young chicks by passive maternally acquired immunity and active immunity induced by early vaccination. The most widely used IBV vaccine strain is H120, which is administered to chicks in the first week of their life. At this age, the potential interference of maternally derived antibodies (MDA) with vaccines may hamper the development of active immunity. In this study, the onset and duration of immunity and the interference of MDAs on the immunogenicity of a live attenuated IB H120 vaccine was assessed. Broilers with and without MDA to IB virus were vaccinated by spray, eye-nose-drop, orally (mimicking drinking water vaccination) or were left non-vaccinated. At three different time points after vaccination, antibody levels to IB virus, and ciliary activity of tracheal explants were measured to assess the efficacy of the vaccine against challenge. No correlation between serum antibody titers and protection could be established, suggesting that local and cell-mediated immunity plays an important role in preventing IBV infections in young birds. There was no influence of MDAs on the vaccination by any of administration methods tested, as judged by level of protection against challenge using ciliostasis scores.