Blastomyces dermatitidis Antibody and Antigen Detection: Comparison of Four Lysate Antigens and Antibodies Prepared from Human Isolates from a Blastomycosis Outbreak.

Blastomycosis is a systemic fungal disease of humans and other animals produced by the thermally dimorphic fungal organism, Blastomyces dermatitidis. Recent studies have focused on the utilization of antibody and antigen detection in the development of immunoassays for the diagnosis of blastomycosis. This study was designed to evaluate four B. dermatitidis yeast lysate antigenic preparations from human isolates (591, 592, 597, 598) from an outbreak of blastomycosis in Eagle River, Wisconsin. The indirect enzyme-linked immunosorbent assay (ELISA) was used to compare these four antigens for their ability to detect antibodies in 28 serum specimens from immunized rabbits and in 18 sera from dogs with blastomycosis. This study also compared antibodies prepared from each of the four B. dermatitidis lysate antigens for their ability to detect antigen using the competitive enzyme-linked immunosorbent assay in 18 urine specimens from the same dogs as above with blastomycosis. All four reagents proved to be immunoreactive and were able to detect antibody in the rabbit and dog sera and antigen in each of the urine specimens with only slight variations in the mean absorbance values evidenced. Antibody detection, mean absorbance values with the four lysates, ranged from 1.522 (592 antigen) to 2.047 (597 antigen) in the rabbit sera and from 1.504 (591 antigen) to 1.878 (597 antigen) in the dog sera. Antigen detection, sensitivity values obtained with the antibodies prepared from the four lysates, ranged from 89% (598 serum) to 100% (591 and 592 serum specimens).

Potential clinical utility of ERC-2 yeast phase lysate antigen for antibody detection in dogs with blastomycosis.

Four Blastomyces antigens ERC-2 (B. gilchristii, dog, Wisconsin), B5929 (human, Minnesota), 597 (human, Wisconsin), and T-27 (polar bear, Tennessee) were tested against 31 serum specimens from dogs with blastomycosis and 19 from healthy dogs. All antigens detected antibody; efficacy varied. ERC-2 showed the highest ELISA mean absorbance value of 3.00 followed by T-27. Test performance varied by sample geographic origin. Further study is needed to determine if ERC-2 antigens may be clinically useful, and whether the combination of the particular fungal species as antigen source, host animal, and the species and geographic location of the patient being tested is important for optimum test characteristics.