INFECTIOUS-BRONCHITIS - EFFECT OF VIRAL DOSES AND ROUTES ON SPECIFIC LACRIMAL AND SERUM ANTIBODY-RESPONSES IN CHICKENS

An enzyme-linked immunosorbent assay was used to measure the effect of various infectious bronchitis virus (IBV) (strain H-120) vaccine dose s and routes of immunization on specific lacrimal and serum antibody r esponses. The results of the first trial showed that the maximum dose, 10(6) median embryo infective doses (EID(50)s), delivered by the ocul ar route elicited both a systemic and a local antibody response in the vaccinated chickens. Lower doses of vaccinal virus, 10(4) (median dos e) and 10(2) (minimum dose) EID50 delivered by the same route did not induce a detectable systemic antibody response. A significant increase of IBV-specific lacrimal IgA was elicited by both the maximum and the median vaccine doses. The low vaccine dose (10(2) EID50) did not indu ce a detectable increase of lacrimal IgA. In a second trial approximat ely the same vaccine dose was administered to different chicken groups by ocular instillation, drinking water, spray, and cloaca. The result s showed that all routes of vaccination tested, including the cloacal route, resulted in an increase of specific serum antibodies. Higher Ig G levels were detected throughout the experimental period after vaccin ation by the ocular route as compared with vaccination via the drinkin g water. All routes of vaccination tested resulted in an increase of s pecific IgA. in lacrimal fluid. The vaccine application methods spray, ocular instillation, and drinking water induced similar lacrimal IgA. responses.