Protection of gerbils from amebic liver abscess by immunization with recombinant Entamoeba histolytica 29-kilodalton antigen.
The goal of our study was to obtain a highly conserved Entamoeba histolytica recombinant antigen for study as a subunit amebiasis vaccine. We screened a Uni-Zap cDNA library of E. histolytica (strain HM1:IMSS) with human immune sera and isolated a dominant 804-bp cDNA clone. A 33-kDa fusion protein expressed from the cDNA clone was determined by monoclonal antibody binding, DNA hybridization, and nucleotide sequence to be the complete E. histolytica 29-kDa antigen. Serum antibodies to the recombinant protein were detected by enzyme-linked immunosorbent assay in 80% of subjects from Egypt and South Africa with amebic liver abscess. Similar results were found with the native 29-kDa protein. Native and recombinant 29-kDa antigens induced proliferation of lymphocytes harvested from patients with amebic liver abscess (P < 0.01 compared with controls). Intraperitoneal immunization of gerbils with the recombinant fusion protein (10 micrograms) with Titermax adjuvant elicited an antigen-specific serum immunoglobulin G antibody response and was partially protective (54%) against intrahepatic challenge with 5 x 10(5) virulent axenic trophozoites (strain HM1:IMSS). In summary, the recombinant form of the E. histolytica 29-kDa antigen demonstrated serologic specificity for amebic liver abscess, exhibited conserved T-cell epitopes, and was effective as a subunit vaccine in an experimental animal model of amebic liver abscess.
Soong
C J
CJ
Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio.
Torian
B E
BE
Abd-Alla
M D
MD
Jackson
T F
TF
Gatharim
V
V
Ravdin
J I
JI
D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology*; D003001:Cloning, Molecular; D004748:Entamoeba histolytica / Q000276:immunology*; D005849:Gerbillinae; D006801:Humans; D008101:Liver Abscess, Amebic / Q000276:immunology / Q000517:prevention & control*; D008297:Male; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic
D000953:Antigens, Protozoan; D011994:Recombinant Proteins; D014614:Vaccines, Synthetic