Enzyme-linked immunosorbent assay for serum antibody to bovine respiratory syncytial virus: comparison with complement-fixation and neutralization tests.

An indirect enzyme-linked immunosorbent assay (ELISA) for the detection of serum antibody to bovine respiratory syncytial virus (BRSV) was developed and compared with complement-fixation (CF) and viral neutralization (VN) tests. Tissue culture-grown viral antigens were used in the tests. Serum samples from various sources were compared, including serum samples from 10 calves which were infected experimentally with BRSV by aerosol exposure. The ELISA compared favorably with the VN test for detecting serologic responses and for detecting passively acquired antibody in young calves. Approximately 98% (109/111) of field serum samples which were positive by the VN test were also positive by ELISA. The ELISA and the CF test both failed to detect early appearing (1 to 4 weeks after exposure) antibody in 2 experimental calves with subclinical infection with BRSV. The CF test appeared to be less specific in that it gave positive reactions with some sera which were negative by both the ELISA and the VN test. The CF test did not detect antibody in 50% of serum samples obtained at the farm from young feeder calves which were positive by both ELISA and the VN test. The ELISA appears to be a sensitive and specific serologic procedure for detecting serum antibody to BRSV and has the advantage of giving test results within several hours, whereas the VN test requires 5 to 6 days for completion.