Recognition of carbohydrate epitopes specific for electron-dense granule antigens from Entamoeba histolytica by monoclonal antibodies in the cecal content of infected hamsters

The pathogenic trophozoites of Entamoeba histolytica produce and secrete el ectron-dense granules (EDG) containing collagenase, considered a virulence factor. Two monoclonal antibodies (MAbs) (L7.1 and L1.1) anti-EDG antigens were raised. MAb L7.1 has been reported to recognize proteic EDG antigens a nd MAb L1.1 reacted with a carbohydrate epitope. These epitopes were presen t in axenic and xenic amoebas. To detect EDG antigens by a enzyme-linked im munosorbent assay (ELISA) in a experimental model of early intestinal amoeb iasis, both MAbs were employed. E. histolytica HMI axenic and monoxenic tro phozoites were inoculated into the cecum according to the washed-closed cec al loop technique. The cecal content was recovered at 8, 24, and 48 h post- inoculation. Antigens from EDG in whole trophozoites and cell-free supernat ants were detected. Our results indicate that it is possible to detect EDG antigens in the cecal content of hamsters in the early phase of the invasiv e amoebiasis.