CHARACTERIZATION OF MONOCLONAL-ANTIBODIES TO CONSERVED ANTIGENS OF ENTAMOEBA-HISTOLYTICA AND E-DISPAR AND DEVELOPMENT OF A STOOL ELISA

Eight murine monoclonal antibodies (MAbs) were generated against Entam oeba histolytica NIH:200. All MAbs reacted with three axenic strains o f E. histolytica, NIH:200, HM-I: IMMS, and SAW 1734R cIAR, but not wit h enteric bacteria or Giardia lamblia. Five of the MAbs reacted with l ow-molecular-weight, periodate-sensitive antigens of 14-21 kD, while o ne (AB31) reacted with high-molecular-weight, 90 to 200-kD protein det erminants. MAb PC14 appeared to be specific for antigen in its native state. Another MAb (BB12) agglutinated live trophozoites and caused me mbrane fluorescence in contrast to the five other MAbs tested. Althoug h BB12 reacted with the same 14 to 21-kD band on Western blot as AC55, the latter reacted with different cytoplasmic epitopes. All the MAbs reacted to five pathogenic (E. histolytica) and six nonpathogenic (E. dispar) clinical isolates. These MAbs may be helpful for studying cons erved antigens off. histolytica and were used to develop a sandwich EL ISA for the diagnosis of intestinal amoebiasis. The assay was sensitiv e to 60 ng of E. histolytica antigen. A comparative study of microscop ic examination of stool samples and the sandwich ELISA was conducted o n 102 samples from patients with gastrointestinal complaints. The ELIS A could detect all microscopically positive samples with a sensitivity of 100% and specificity of 93%. A sandwich ELISA using a monoclonal a ntibody to conserved antigens of E. histolytica has the potential to b e a reliable method for the diagnosis of intestinal amoebiasis.