Serological studies with reoviruses in chickens, turkeys and ducks.

Fluorescent antibody (FA) studies with avian reoviruses in chickens, turkeys and ducks are described. Detection of the group-specific antigen by FA test was investigated by titrating a reovirus antiserum on chick embryo liver cell cultures infected with 18 reovirus strains fixed on multitest slides. With 16 of the viruses, test titres were similar, indicating presence of a common antigen. The titre observed with a duck reovirus isolate was considerably lower, suggesting partial cross-reactivity. One virus (Kosters) was not stained. A comparison of the agar gel immuno-diffusion (AGID) test with the FA test on serial dilutions of antiserum demonstrated the greater sensitivity of the FA test. In a survey of chicken and turkey sera for reovirus antibodies by both tests, a higher percentage positive was recorded by immunofluorescence with CS108 virus as antigen. No antibodies to this virus were detected in 46 duck sera but 4 sera were positive for the duck reovirus isolate. Of 100 chicken sera, 19 were positive for duck reovirus and 6 for Kosters virus. No antibodies to either of these viruses were found in turkey sera. The results demonstrate the usefulness of the indirect FA test with multitest slides for avian reovirus serology and indicate the existence of atypical strains with no or partial group antigen reactivity.