Local and systemic specific antibody response of different chicken lines after ocular vaccination against infectious bronchitis.

The specific lacrimal fluid IgA levels and the specific serum IgG levels of broiler chicks (meat type hybrids (MT)), brown-egg layer chicks (heavy layer (HL)), and white leghorn chicks (light layer (LL)) were compared after infectious bronchitis virus (IBV) ocular vaccination at 1 day of age. All birds were maintained as a mixed population throughout the experiment of 45 days. The class specific antibody levels were determined at regular intervals by enzyme-linked immunosorbent assays. All birds responded to the vaccination stimulus as shown by a significant increase of antibody levels in both serum and lacrimal fluid. When comparing the IgG response of the chicken lines tested, LL chicks showed higher serum IBV-IgG values at the time of maximal response at days 5 and 9 post-vaccination (pv). This bird group also showed a more homogeneous (lowest coefficient of variation of values) serum IgG response. On day 13 pv and until the last serum sampling day (day 41 pv) all three chicken types showed statistically identical serum IBV-IgG levels. The local IgA response detected in lacrimal fluids showed differences between the chicks at the time of maximal levels (days 5 to 14 pv), the response of LL chicks being the highest. LL chicks maintained higher specific IgA levels than MT and HL chicks almost throughout the experimental period. According to the coefficient of variation of the absorbance values (36%), the IgA response shown by LL chicks was the most homogeneous.