DETECTION OF ANTIBODIES AND DELAYED DERMAL HYPERSENSITIVITY WITH DIFFERENT LOTS OF BLASTOMYCES-DERMATITIDIS YEAST LYSATE ANTIGEN - STABILITY AND SPECIFICITY EVALUATIONS

Comparative evaluations were performed to assess the stability, sensit ivity and specificity of eight lots of yeast lysate antigen prepared f rom a Blastomyces dermatitidis dog isolate (T-58). These antigens were prepared during the period from 1989 to 1995. The lysates were used i n an ELISA for the detection of antibodies in serum specimens from dog s with blastomycosis and histoplasmosis. In order to evaluate the abil ity of the lysates to elicit delayed dermal hypersensitivity (DTH) res ponses, they were compared as skin-testing antigens in guinea pigs tha t were previously sensitized with B. dermatitidis or Histoplasma capsu latum killed whole yeast cells. All 8 of the lots of antigen detected antibody in the sera from dogs with blastomycosis (absorbance values r anged from 0.432 to 0.543; mean value of 0.508). The absorbance values ranged from 0.283 to 0.439 (mean value of 0.326) when the lysates wer e assayed against sera from dogs with histoplasmosis. All of the antig ens were able to elicit a DTH response in B. dermatitidis immunized an imals (mean axes of induration values ranged from 10.5 mm to 12.5 mm; mean value of 11.6 mm). In contrast, only minimal cross-reactivity was evidenced in the guinea pigs immunized with H. capsulatum (mean axes of induration values ranged from 0 to 4.5 mm; mean value of induration of 1.7 mm).