A comparison of three methods for detecting antibodies to turkey rhinotracheitis virus

Sera from a flock of naturally infected commercial turkeys were tested for antibodies against turkey rhinotracheitis virus using an indirect immunofluorescence test with infected turkey embryo tracheal organ cultures, a serum neutralisation test using chick embryo fibro-blasts or liver cells and an ELISA. Antibodies were detected by all tests within 5 days of the appearance of clinical respiratory disease. Serum neutralising antibodies detected in chick embryo fibroblasts rapidly achieved their peak titres and were decreasing by day 13. ELISA antibodies peaked on day 13. On days 13 and 34 significant correlations were obtained for immunofluorescence and ELISA and for ELISA and microneutralisation in fibroblasts. For both the latter tests there was a good correlation between the results obtained for individual birds within the flock on days 13 and 34. ELISA and serum neutralisation in chick embryo fibroblast monolayers would appear to be sensitive and reliable tests for detecting circulating antibodies against turkey rhinotracheitis virus in commercial flocks.