Sensitivity and specificity of an isoelectric focusing fraction of Blastomyces dermatitidis yeast lysate antigen for the detection of canine blastomycosis.

Blastomyces dermatitidis yeast lysate antigen (T-58, dog isolate) fractions prepared using the Rotofor preparative isoelectric focusing (IEF) cell (Bio-Rad) were compared with B. dermatitidis yeast lysate and filtrate reagents with respect to the detection of antibodies in sera from dogs with blastomycosis, histoplasmosis, coccidioidomycosis, cryptococcosis and aspergillosis. A horseradish peroxidase enzyme immunoassay with Turbo TMB substrate was used in the study. One particular IEF fraction (pH 4.3) was optimal in the assay, and it exhibited greater sensitivity (100%) and specificity (93%) than the lysate or filtrate preparations. The highest degree of cross-reactivity was encountered with the histoplasmosis and coccidioidomycosis specimens and considerably less with the cryptococcosis and aspergillosis sera. Studies are in progress to purify further the optimal IEF fraction.