Comparative serological studies with egg drop syndrome virus

The sensitivities of five serological tests (haemagglutination inhibition, ELISA, serum neutralisation, fluorescent antibody and agar gel immunodiffusion) for detection of Egg Drop Syndrome virus antibody were compared. In experimentally inoculated birds seroconversion was first detected at five days post-inoculation using haemagglutination inhibition, ELISA, serum neutralisation and fluorescent antibody test, and at seven days post-inoculation using agar gel immunodiffusion. Sera from birds experimentally infected with two or more different fowl adenovirus serotypes gave positive reactions in some of these tests, as did a small percentage of haemagglutination inhibition negative field sera. It is concluded that only haemagglutination inhibition or serum neutralisation should be used for detection of infection in commercial birds.