Sensitivity and Specificity of a Monoclonal Antibody-Based Fluorescence Assay for Detecting Enterocytozoon bieneusi Spores in Feces of Simian Immunodeficiency Virus-Infected Macaques

Enterocytozoon bieneusi is clinically the most significant among the microsporidia causing chronic diarrhea, wasting, and cholangitis in individuals with human immunodeficiency virus/AIDS. Microscopy with either calcofluor or modified trichrome stains is the standard diagnostic test for microsporidiosis and does not allow species identification. Detection of E. bieneusi infection based on PCR is limited to a few reference laboratories, and thus it is not the standard diagnostic assay. We have recently reported the development and characterization of a panel of monoclonal antibodies against E. bieneusi , and in this publication we evaluated the specificity and sensitivity of an immunofluorescence assay (IFA), compared with PCR, in simian immunodeficiency virus-infected macaques. The IFA, which correlated with the primary PCR method, with a detection limit of 1.5 ×10 5 spores per gram of feces, will simplify considerably the detection of E. bieneusi spores in clinical and environmental specimens and in laboratory and epidemiological investigations.