<i>Blastomyces dermatitidis</i> Antibody Responses in Serial Serum Specimens from Dogs with Blastomycosis: Comparison of Different Yeast Lysate Antigens

The systemic fungal organism, Blastomyces dermatitidis causes blastomycosis in animals and hu-mans. This study was designed to evaluate antibody detection in 55 serial serum specimens from 9 dogs with blastomycosis using B. dermatitidis yeast lysate antigens produced from two human isolates (B5896; B5931) and two dog isolates (ERC-2; T-58) with the indirect enzyme linked im-munosorbent assay (ELISA; peroxidase system) to determine an optimal lysate antigen(s) for use in the ELISA to detect antibody in the dog serum specimens. The mean absorbance values when the lysate antigens were compared with respect to their ability to detect antibody in the day 0 sera from the 9 dogs were 1.024 (ERC-2), 1.351 (B5896), 1.700 (B5931) and 2.084 (T-58) respectively. All of the reagents exhibited a high level of sensitivity and in all instances the amount of antibody declined as the time interval post-treatment increased, but the T-58 lysate prepared from the dog isolate from Tennessee was the optimal reagent. We continue to evaluate antigens for B. derma-titidis antibody detection in different immunodiagnostic assays.