Monoclonal antibodies which inhibit in vitro cytotoxicity of axenic Entamoeba histolytica.

A panel of 12 independent hybridoma cell lines secreting monoclonal antibodies to axenic E. histolytica (HM1) have been developed. A hybridoma cell line P4 C4 P2 F8 C8 (clone C8) produced monoclonal antibodies (MoAb C8) of IgG1 isotype which recognised a 29 KD surface associated antigen of amoebic trophozoites in Western immunoblot. Immunofluorescent probing with MoAb C8 employing live and acetone fixed amoebic trophozoites indicated 29 KD molecule on the surface plasma membrane of E. histolytica trophozoites. The MoAb C8 also agglutinated the live amoebic trophozoites. Pretreatment of amoebic trophozoites with anti 29 KD monoclonal antibody significantly (P less than 0.01) inhibited in vitro cytotoxicity of amoebic trophozoites to the cultured baby hamster kidney (BHK-21) cells. MoAb recognised a 29 KD molecule of E. histolytica trophozoites which mediated cytotoxic potentials of the parasite. The absence or variable degree of expression of cytotoxic 29 KD molecule may possibly serve as a marker to differentiate virulent/avirulent populations or strains of E. histolytica.

Characteristics of Escherichia coli isolates from infantile and childhood diarrhea.

Seventy-five strains of Escherichia coli from cases of infantile and childhood diarrhea were serogrouped and analysed in terms of hydrophobicity, mannose resistant haemagglutination and enterotoxigenicity. The strains were distributed over 21 serogroups of which 54.6% were hydrophobic, 37.3% were haemagglutinating and 66.5% were enterotoxigenic. EPEC strains were less than ETEC strains. LT producers were more than LTST or ST producers. MRHA activity was found to be well correlated with hydrophobicity.