Comparative antigenic studies of species of Basidiobolus and other medically important fungi.

An immunodiffusion technique was used to evaluate the antigenic relationship of various pathogenic and saprobic Basidiobolus spp., Conidiobolus spp., isolates of the order Mucorales, and several other medically important nonzygomycetous fungi. The antiserum to Basidiobolus haptosporus shared two lines of identity, designated inner (N) and outer (Y), when tested against exoantigens of known strains of B. haptosporus and Basidiobolus ranarum as well as exoantigens of a human Nigerian isolate and several wild isolates tentatively identified in B. ranarum. Both bands were heat stable at 56 degrees C for 30 min. Exoantigens of strains of Basidiobolus meristosporus, Basidiobolus microsporus, Conidiobolus incongruus, Conidiobolus coronatus, and other wild isolates of Basidiobolus spp. tested formed only the N immunoprecipitin band. Exoantigens of 10 isolates from other taxa did not produce any cross-reactive precipitin line. B. meristosporus antiserum that was tested against exoantigens of Basidiobolus spp. and of Conidiobolus spp. developed only an N band without a Y band. These data suggest that B. haptosporus and B. ranarum are antigenically similar to each other and distinct from B. meristosporus. Basidiobolus spp. and Conidiobolus spp. share a common N immunoprecipitin band, which implies a taxonomic relationship between these two genera. The absence of lines of identity between Basidiobolus spp. and other fungi tested suggests that, antigenically, Basidiobolus is a distinct genus.