Studies on bovine leucosis V. A comparative study on the practical value of the agar gel immunodiffusion test, the indirect fluorescent antibody technique and the micro complement fixation test for the detection of antibodies to bovine leucosis virus.

The practical value of the indirect fluorescent antibody technique (I FAT), the micro complement fixation test (M CFT) and the agar gel immunodiffusion test (AGIDT) for the detection of antibodies to bovine leucosis virus (BLV) was investigated. For this purpose 1495 serum samples were examined. There was a remarkably good agreement between the three tests in the demonstration of antibodies to BLV especially if sera with a sufficient high concentration of antibodies ("late serum") were under investigation. These positive sera were derived only from farms which exploited one or more imported animals. A disagreement of results of the three tests was observed in 38 (2.5%) cases. This was due to: (1) difficulties in reading of the test; (2) presumably by the demonstration of different classes of antibody and (3) the fact that in the AGIDT sera could be used undiluted. This discrepancy was especially evident with sera with a low concentration of antibodies ("early or incubation sera"). A drawback for the M CFT is the anticomplementary activity found in 17% of the bovine serum samples.