Non-pathogenic Entamoeba histolytica: functional and biochemical characterization of a monoxenic strain.
We have cultured under monoxenic conditions and characterized an Entamoeba histolytica clone, MAV-I CINVESTAV (MAV-I), obtained from feces from an asymptomatic carrier. The clone shows the non-pathogenic E. histolytica zymodeme type I, which did not change through the process of monoxenization. Clone MAV-I was non-pathogenic in both in vivo and in vitro tests, and it did not have a functional 112-kDa adhesin. As far as we know, this is the first non-pathogenic monoxenic strain reported. Clone A (strain HM1:IMSS), a highly virulent clone with pathogenic zymodeme type II, and which has the 112-kDa adhesin, was used as a control. Protein patterns from both clones were almost identical in one-dimensional gels. In two-dimensional gels, differences in high-molecular-weight proteins were detected. Clone MAV-I adhered and phagocytosed only 12% of the red blood cells adhered and phagocytosed by clone A. MAV-I trophozoites did not destroy cell culture monolayers and did not produce hepatic abscesses in hamsters. They also showed deficiency in protease activity. The absence of virulence in clone MAV-I correlated directly with the absence of a functional 112-kDa adhesion, supporting the role that this protein plays in virulence.
Vargas
M A
MA
Departamento de Genética y Biología Molecular, CINVESTAV, Mexico City, Mexico.
Isibasi
A
A
Kumate
J
J
Orozco
E
E
D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology; D002478:Cells, Cultured; D004748:Entamoeba histolytica / Q000276:immunology / Q000472:pathogenicity / Q000502:physiology*; D005243:Feces / Q000469:parasitology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008100:Liver Abscess / Q000276:immunology; D014774:Virulence
D000953:Antigens, Protozoan; D007074:Immunoglobulin G