CROSS-REACTIVE CELLULAR IMMUNE-RESPONSES IN CHICKENS VACCINATED WITH LIVE INFECTIOUS-BRONCHITIS VIRUS-VACCINE

Two-week-old chickens were vaccinated intra-nasally with a live infect ious bronchitis virus (IBV) vaccine (H120). On days 4, 7, 11 and 14 po st-vaccination (p.v.) spleen mononuclear cells (MNC) prepared from con trol and vaccinated chickens were stimulated in vitro with homologous (strain M41) and heterologous (strains 7 and 793/B) virus antigens. An tigen-specific lymphoproliferation and interleukin-2 (IL-2) and interf eron-gamma (IFN) production were used to measure cross-reactive cell m ediated immune responses. In antigen-specific lymphoproliferation assa ys, it was found that while 4/16 vaccinated birds responded to the hom ologous antigen, only one responded to an heterologous antigen (strain 7). However, IL-2 production was seen in the supernatants of spleen M NC from vaccinated chickens stimulated with all three antigens. Produc tion of IFN was also demonstrated in samples stimulated with the homol ogous and one heterologous (strain 7) antigen. Thus it appears that, f ollowing vaccination of chickens with live IBV vaccine, cross-reactive cellular immune responses occur that vary in magnitude with the strai n of IBV used for in vitro stimulation.