Blastomycosis, the systemic fungal infection of humans and animals, has presented a diagnostic challenge to clinicians and laboratory personnel for many years. Our laboratory has been concentrating on attempting to develop antigenic reagents from the yeast phase of various isolates of Blastomyces dermatitidis and to evaluate these lysate antigens with regard to antibody detection in blastomycosis. The aim of this current study was to evaluate yeast phase antigens prepared from four dog isolates of B. dermatitidis and to evaluate their efficacy, when used individually or in combination, for antibody detection in sera from dogs with blastomycosis. Mean absorbance values using the ELISA to assay 24 serum specimens (Trial 1) ranged from 0.588 with an individual lysate antigen to 0.992 when three reagents were combined. Eight of the lysates exhibited mean absorbance values ranging from 0.992 to 0.915 with 7 out of 8 being lysate antigen combinations. Mean absorbance values with the other 6 lysates ranged from 0.899 to 0.588. In Trial 2, the 6 most sensitive reagents from Trial 1 were assayed against 10 highly reactive dog sera. The results of Trial 2 showed that 5 antigen combinations detected antibody to a greater degree than the individual lysate antigen. Combinations of northern and southern antigens were able to detect antibody in serum specimens from either of these geographical regions. Comparative studies are continuing to further evaluate various lysate antigen combinations for antibody detection in blastomycosis.

The systemic fungal infection, blastomycosis, which infects both humans and animals has presented a diagnostic challenge for clinicians for many years. The aim of this study was to evaluate the diagnostic sensitivity of Blastomyces dermatitidis yeast lysate antigens with respect to antibody detection in dogs with blastomycosis. Lysate antigens were prepared from B. dermatitidis isolates T-58 and T-66 (dogs, Tennessee) and WI-R and WI-J (dogs, Wisconsin). Based on results obtained from a preliminary comparative study, five combinations of these isolates and one individual isolate were tested against 92 serum specimens from dogs with culture-proven or histologically-confirmed blastomycosis, using the indirect enzyme-linked immunosorbent assay (ELISA). Mean absorbance values obtained from the sera ranged from 0.905 with the individual T-58 antigen to 1.760 using an antigen combination (T-58 + T-66 + WI-R). All of the 6 antigenic preparations were able to detect antibody in the serum specimens, but the antigen combinations detected antibody to a higher degree than the individual antigen. This study provides evidence that combinations of the yeast lysate reagents seem to be more efficacious for antibody detection in dog sera, but our laboratory is continuing to evaluate antigen lysate combinations for detection of antibodies in blastomycosis.