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

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.