A comparison of some serological tests for bluetongue virus infection.

The plaque neutralization, complement fixation, and agar gel precipitin tests were compared by measuring bluetongue virus antibody in 137 serums from experimental animals (cattle and sheep) and suspected field reactors (cattle and deer). In general, the tests agreed well with each other. Plaque neutralization titers began earlier than the other two and went much higher than the complement fixation titers. Plaque neutralization titers usually peaked between two and three weeks after exposure and complement fixation titers from four to six weeks. The greater sensitivity of the plaque neutralization test allowed the detection of all complement fixation and agar gel precipitin reactors whereas occasionally the latter two tests failed to detect plaque neutralization reactors.