An evaluation of four serological tests for the detection of antibodies to bovine parainfluenza virus type 3.

Haemagglutination-inhibition (HI), virus neutralization (VN), haemolysis-inhibition (HLI-1, HLI-2) tests, and two new haemofusion-inhibition (HFI-1, HFI-2) tests, developed by us, were tested for the detection of antibodies to bovine parainfluenza virus type 3 (BPIV-3) in sera of 45 steers randomly selected from a herd naturally infected by BPIV-3. Twelve seronegative animals were then vaccinated with formalin-inactivated vaccine and 15 days later tested by the above-mentioned assays. Linear regression analysis revealed positive correlations between HI, VN, HLI-1 and HFI-1 antibody titres, which confirm the specificity of the HFI-1 test. The HLI-1 and HFI-1 assays proved to be less sensitive than the HI and VN ones, while HLI-2 and HFI-2 tests failed to detect any antibody to BPIV-3.