Page 1426 - Veterinary Immunology, 10th Edition

positive reaction. A similar test is used to identify cattle infected
VetBooks.ir with bovine leukemia virus. Immunodiffusion assays are, however,

very insensitive and as a result are subject to numerous false-
negative results. ELISA tests are significantly more sensitive. Thus

the combination of ELISA plus immunodiffusion resulted in the
detection of 17% more positive cases of EIA. These false-negative
results would ensure that EIA cannot be eradicated if testing were
based on the Coggins test alone.

FIG. 42.22 The gel diffusion technique may be used to determine
the relationship of two antigens.

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