Serological differentiation of microsporidia with special reference to Trachipleistophora hominis.

Myositis is a common clinical syndrome in advanced stages of AIDS. Trachipleistophora hominis (phylum Microspora) has been detected in several cases of painful, immobilising myositis in AIDS patients. Enzyme linked immunosorbent assays (ELISAs) and Western blotting of protein profiles separated by SDS PAGE were used to determine whether this species could be detected and differentiated by serology. Sixteen microsporidia, including several species known to infect man and species infecting fish, crustaceans and a mosquito, were used as antigen. Each species had a unique profile of SDS PAGE-separated proteins. In Western blots, mouse antiserum, raised to T. hominis and selected for its high ELISA specificity, bound to antigens ranging from less than 25 kDa to greater than 250 kDa with major bands at 39-44 kDa and 98-150 kDa on T. hominis protein profiles. The serum also recognised some high molecular weight antigens in the profiles of Vavraia culicis, Heterosporis anguillarum, and three species of Pleistophora but none in the remaining genera examined. It was concluded that ELISA and Western blotting could be used to detect and differentiate T. hominis in muscle biopsy tissue from patients with myositis. However, sera from T. hominis-infected patients in the terminal stages of AIDS would not be useful for detection of infections because of a sharp decline in antibody level.