Serological differences in three Blastomyces dermatitidis strains

Yeast phase lysate antigens, prepared from three isolates of Blastomyces dermatitidis (T-58, Tennessee dog; 48089, Zaire human; ERC-2, Wisconsin dog) were assayed for their ability to detect antibodies in human sera, dog sera and sera from rabbits immunized with each of the lysate antigens. The dog sera were from animals diagnosed with blastomycosis from various endemic regions in North America. T-58 and ERC-2 lysate antigens exhibited a high reactivity with the serum from dogs infected with blastomycosis; however, 48089 lysate showed low reactivity with the same sera. With the immunized rabbit sera, 48089 lysate was the only lysate with a high reactivity with the 48089 serum and it exhibited little reactivity with the heterologous sera. The T-58 and ERC-2 lysate antigens reacted minimally with the 48089 serum but reacted highly with both the T-58 and ERC-2 sera. The human sera were from individuals potentially exposed to B. dermatitidis while working on a prairie dog relocation project in Colorado. Remarkably, all three lysate antigens could detect antibodies in the individuals diagnosed with blastomycosis. This study indicated that there were serological differences in the 48089 Zaire lysate compared with the other lysate antigens and it may be designated serotype 2.