Immunological Studies on the Fungal Genus Smittium (Trichomycetes)

SUMMARY

Immunological comparisons of cultured species of Smittium isolated from the hindguts of Diptera larvae were made using immunoelectropho-retic and immunodiffusion methods. Antisera were produced in rabbits against eight of the 21 antigenic extracts of Smittium isolates. Antigen extracts from three species of Mucorales, three species of Entomophthorales, and Amoebidium parasiticum were included in the studies for comparison with species of Smittium. Immunoelectrophoretic and immunodiffusion data were processed using computerized, numerical taxonomic methods which included cluster and principal component analyses. Results indicated that the groupings of Smittium species obtained from immunoelectrophoretic data corresponded well with those based on morphology, whereas immunodiffusion data had somewhat lower correspondence. The results also suggest that spore morphology generally is a reliable taxonomic character for Smittium species, but host specificity must be used with caution. Amoebidium and Smittium are unrelated serologically. Occasional immunological correspondence between two of the Mucorales (Kickxellaceae), Linderina pennispora and Dipsacomyces acuminosporus, and some of the Smittium species suggests that this and other evidence of relationships should be reinvestigated.