DETECTION OF MICROSPORIDIAN SPORES IN CLINICAL-SAMPLES BY INDIRECT FLUORESCENT-ANTIBODY ASSAY USING WHOLE-CELL ANTISERA TO ENCEPHALITOZOON-CUNICULI AND ENCEPHALITOZOON-HELLEM

Three polyclonal mouse antisera, to Encephalitozoon cuniculi, Nosema a lgerae, and Nosema corneum, and two polyclonal rabbit antisera, to E. cuniculi and Encephalitozoon hellem, were used in an indirect fluoresc ent-antibody assay (IFA) with Enterocytozoon bieneusi, E. cuniculi, an d Encephalitgozoon. hellem spores (spores of the last two were taken f rom culture). Enterocytozoon bieneusi cannot be cultured. By IFA, anti sera to E. cuniculi and E. hellem reacted strongly and equally with ea ch other's spores. The mouse antisera reacted strongly with the homolo gous species, but for these there was segmental and particulate or ''d ot'' staining of heterologous microsporidian spores, indicating cross- reactions with more selected antigens. In fecal samples, cross-reactio ns with both mouse and rabbit antisera were sometimes seen with differ ent yeast species, with species of streptococci, and species of gram-n egative rods. There were no cross-reactions to staphylococci. Enterocy tozoon bieneusi was easily identified in duodenal and colonic biopsies , duodenal and colonic fluids, and feces of symptomatic AIDS patients by IFA. In a study of 12 AIDS patients with diarrhea, the new IFA iden tified microsporidia in all of 11 fecal samples, three colon fluids, s ix duodenal fluids, and three duodenal biopsy touch preparations. Alth ough the fecal sample of 1 of the 12 was negative, the patient's duode nal fluid contained microsporidian spores by IFA.