Studies on antigens from agents causing black grain eumycetoma.

Culture filtrate and cellular antigens prepared from 14 agents which cause black grain eumycetoma were compared by double diffusion and immunoelectrophoresis. The fungal agents studied included five isolates of Madurella grisea, two of Madurella mycetomatis and a single isolate each of Pyrenochaeta mackinnonii, Pyrenochaeta romeroi, Chaetosphaeronema (Pseudochaetosphaeronema) larense, Plenodomus avramii, Phoma/Phyllosticta, Aureobasidium (Exophiala) mansonii and Leptosphaeria senegalensis. Cross-comparisons between all paired combinations of antigens and rabbit antisera raised against each antigen, before and after absorption with heterologous antigens, were expressed as percentage homologies. Cross-reactivity was marked (up to 90%) within the M. grisea group and between M. grisea and P. mackinnonii, but not with P. romeroi. The results suggest that the representatives of the M. grisea group tested were similar or identical to P. mackinnonii. Little antigenic similarity was observed between M. grisea and M. mycetomatis. The remaining antigens and antisera reacted most strongly with their homologous counterparts, except for L. senegalensis which had antigens in common with M. grisea (0-55% homology) and P. mackinnonii (70% homology). Analysis of the antigenic patterns derived from five of six unidentified isolates from patients with black grain eumycetoma showed marked similarity to M. grisea and P. mackinnonii.