EN
The results of serological examinations of chickens after their experimental immunization with inactivated Campylobacter jejuni vaccine given subcutaneously (two groups aged from 10-18 days and 21-28 days) or infected orally on day 3 or broilers and laying hens infected under field conditions have been presented. The level of specific antibodies in sera of immunized chickens (OD ELISA mean values in chickens aged between 10-18 days were 0.316 and aged between 21-28 days (0.475) did not protect them from experimental infection carried out in week two after the second dose of the vaccine. However, two or three day delays in Campylobacter colonization were observed following infection with C. jejuni (strain Lio 1). Maternal antibodies (OD ELISA - 0.480) in chickens aged 3 days infected per os did not protect them from the infection. The analysis of OD ELISA values obtained from hens infected under field conditions demonstrated the relationship between these values and the age and clinical status of poultry. In older and clinically sick birds the values were significantly higher (0.837-1.351 in hens and 0.461-1.532 in chickens) than those in clinically healthy birds (0.417-0.863 and 0.264-0.490, respectively. The serological tests applied (ELISA and AGP) proved to be useful to detect antibodies against Campylobacter infections. Precipitating antibodies were found more often in poultry infected parenterally in field conditions, and in sick birds.