A monoclonal antibody-based test system for detection of Entamoeba histolytica-specific coproantigen.

ABSTRACT

BACKGROUND: Diagnosis of amebiasis based on stool microscopy or demonstration of anti-amebic antibodies has limitations. A diagnostic system based on demonstration of the parasite product in clinical specimens holds promise. METHODS: Murine monoclonal antibodies were developed against an Entamoeba histolytica-specific coproantigen. A monoclonal antibody (MoAb) 3D10 was employed in a double-antibody sandwich microELISA system for the detection of amebic coproantigen in fecal specimens. The system was evaluated in three groups of subjects: 63 patients with intestinal amebae, 27 with non-amebic parasitosis, and 57 apparently healthy controls. RESULTS: The MoAb 3D10 belonged to IgG1 isotype and recognized three antigens, with mol. wt. 36, 25 and 17 kDa in the crude extract of E. histolytica (HM1-IMSS), and an amebic coproantigen with MW 36 kDa in the stool supernatant from patients with intestinal amebae. The coproantigen was detected in the stool eluates of 56 (89%) patients with intestinal amebae and in none of the stool eluates from other subjects, thereby giving this system a sensitivity of 89% and specificity of 100% for the detection of intestinal amebae. CONCLUSIONS: This monoclonal antibody recognizes as intact epitope on the E. histolytica-specific coproantigen. The validity of the MoAb-based microELISA system needs to be established.