Relative sensitivity and specificity of agar gel immunodiffusion, enzyme immunosorbent assay, and immunoblotting for detection of anti-bovine leukemia virus antibodies in cattle.

Three serologic methods for the detection of antibodies to bovine leukemia virus (BLV) were compared using the sera of 140 dairy cows. A widely used commercial agarose immunodiffusion screening assay and a commercial antibody capture enzyme immunosorbent assay were compared for sensitivity and specificity with immunoblotting as the standard. The immunoblot utilized the same antigen preparations that were provided in the commercial kits. The agarose immunodiffusion and the enzyme immunosorbent assay were comparable in the number of positive animals detected. However, the commercial screening kits failed to detect 39% (agarose immunodiffusion) and 35% (immunosorbent assay), respectively, of the animals determined serologically positive by immunoblot. These findings corroborate those of some other groups and emphasize the need for more sensitive tests to identify BLV positive cattle for culling or separation in order to create BLV-free herds.