Studies on the serological detection of antibodies to avian encephalomyelitis virus

An avian encephalomyelitis virus (AEV) antigen, prepared from the gastrointestinal tract of infected chick embryos and partially purified and concentrated by chloroform and polyethylene glycol treatments, exhibited the highest reactivity in the agar-gel precipitin test (AGPT). Antigen used in the passive haemagglutination test (PHAT) that was purified and concentrated yielded higher antibody titres than when untreated crude antigens were used. The use of the AGPT, PHAT and embryo susceptibility test (EST) on chicken breeding flocks with and without a history of previous vaccination against AE revealed that the PHAT was more sensitive in detecting AEV antibodies than the AGPT. The sensitivity of the PHAT was nearly equal to the EST. No correlation was found between the results of the AGPT and the immune status of a flock judged by the EST.