EN
In twenty broiler flocks the following antibodies against common viruses were evaluated: chicken anaemia (CAV), infection bursal disease (IBDV), infection bronchitis (IBV) and reoviruses. The antibodies against Marek’s disease virus (MDV) were additionally examined. The presence of antibodies against CAV, IBDV and IB was determined by comercial ELISA kits and against reoviruses by ELISA performed according to the modified method of Slaght. The antibodies against CAV occurred in 7 flocks, the percentage of positive sera was 5% to 22%. All the sera showed the presence of IBDV antibodies. The antibodies against IBV were found in 5 flocks. In 7 flocks 80% of sera were positive. The antibodies against reoviruses were found in 90% of the flocks examined. All sera were positive in 8 flocks and negative in 2 flocks. In 6 flocks antibodies against MDV were found in 5% to 40% of the chickens.