title: Use of a recombinant 170-kilodalton surface antigen of Entamoeba histolytica for serodiagnosis of amebiasis and identification of immunodominant domains of the native molecule.
abstract: We expressed the gene that encodes one of the major surface antigens of Entamoeba histolytica, the 170-kDa protein (1,270 amino acids), as a glutathione S-transferase fusion protein containing amino acids 1 to 1202 (lacking the putative transmembrane and cytoplasmic regions) and as separate fusion proteins containing each of three major domains of the 170-kDa molecule. Lysates from bacteria induced to express one of these proteins were used as the target antigens in a Western blot (immunoblot) analysis to determine whether a recombinant 170-kDa antigen could serve as the basis for a serologic test used to detect invasive amebiasis and whether there are differences in humoral immunogenicity among the three major domains of the 170-kDa antigen. Among patients with invasive amebiasis from three major areas where the disease is endemic and two sites in the United States, 54 (90%) of 60 had antibodies to the recombinant 170-kDa protein. Among 37 patients from regions where the disease is endemic and 20 patients from the United States without amebic disease, 1 (2%) of 57 had antibodies to the recombinant 170-kDa protein. We found significant differences in seroreactivity to each of three major domains of the molecule among patients seropositive for the complete construct, ranging from 100% seroreactivity with the fusion protein containing the domain designated cysteine rich and 89% seropositivity with the fusion protein incorporating a portion of the region designated cysteine poor to only 9% seropositivity for the fusion protein containing the pseudorepeat domain. Our study indicates that a serologic test based on the recombinant 170-kDA antigen could serve as a highly sensitive and specific test for acute invasive amebiasis.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: E
authors.initials: E
authors.lastname: Li
authors.forename: T F
authors.initials: TF
authors.lastname: Jackson
authors.forename: T
authors.initials: T
authors.lastname: Zhang
authors.forename: V
authors.initials: V
authors.lastname: Gathiram
authors.forename: S L
authors.initials: SL
authors.lastname: Stanley
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics; D000954:Antigens, Surface / Q000235:genetics; D015153:Blotting, Western / Q000379:methods / Q000706:statistics & numerical data; D016054:DNA, Protozoan / Q000235:genetics; D004748:Entamoeba histolytica / Q000235:genetics / Q000276:immunology*; D004749:Entamoebiasis / Q000175:diagnosis*; D005069:Evaluation Studies as Topic; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods / Q000706:statistics & numerical data
chemical_list: D000953:Antigens, Protozoan; D000954:Antigens, Surface; D016054:DNA, Protozoan; D011994:Recombinant Proteins