CHICKEN ANEMIA VIRUS-ANTIBODY ELISA - PROBLEMS WITH NONSPECIFIC REACTIONS

For accreditation of CSIRO specific pathogen-free flocks, chicken sera are routinely tested for antibody to chicken anaemia virus (CAV) usin g a commercially available ELISA kit. On some occasions recently, up t o 18.2% positive reactions have been found in individual isolators, wi th an overall reaction rate of 2.7%. On subsequent bleeding the majori ty of the suspected birds have given negative reactions, indicating th at the earlier reactions were false-positives. The protein composition of the sera that appeared CAV-negative or -positive in the ELISA were compared using various chromatographic techniques. Separation of seru m proteins by high resolution size exclusion chromatography revealed t hat in the false-positive sera the antigen-binding activity is associa ted with a protein fraction which was different from mat found in the true-positive sera.