Double-antibody sandwich ELISA for detection of infectious bursal disease virus

A double-antibody sandwich ELISA was employed for detection of IBD virus in bursal suspension. Fifty IBD-free white leghorn chickens aged 5 weeks were experimentally infected with IBD virus. Bursae were collected 4, 8, 12, 24, 36 and 48 hours and 3, 4 and 5 days post-infection. An equal number of chickens acted as appropriate controls. The colour difference between a positive and a negative reaction was clearly distinguished with the naked eye. The cut-off level between ELISA negative and ELISA positive absorbance values was estimated at mean absorbance of negative controls plus three times the standard deviation.