Protection of gerbils from amebic liver abscess by immunization with a recombinant Entamoeba histolytica antigen.
Amebiasis, infection by the intestinal protozoan parasite Entamoeba histolytica, is a leading parasitic cause of death. As a step in the development of a recombinant antigen vaccine to prevent E. histolytica infection, we looked at the ability of a recombinant version of the serine-rich E. histolytica protein (SREHP) to elicit a protective immune response against invasive amebic disease. Gerbils, a standard model for amebic liver abscess, were immunized with either a recombinant SREHP/maltose-binding protein (MBP) fusion, recombinant MBP alone, or phosphate-buffered saline (PBS), all combined with complete Freund's adjuvant. In the first trial (group 1), gerbils received a primary and two booster immunizations intraperitoneally; in the second trial (group 2), gerbils were immunized by a single intradermal injection. SREHP/MBP-immunized gerbils in both groups produced antibody to native SHEHP and developed delayed-type hypersensitivity responses to recombinant SREHP. All gerbils were challenged by an intrahepatic injection with 5 x 10(4) virulent E. histolytica HM1-IMSS trophozoites. Complete protection from amebic liver abscess was seen in 64% of the SHEHP/MBP-immunized gerbils in group 1 and in 100% of the SREHP/MBP-immunized gerbils in group 2. There was no protection observed in MBP- or PBS-immunized gerbils in either group. Our results indicate that the SREHP molecule has potential as a vaccine to prevent amebic infection and demonstrate that successful vaccination of animals with recombinant E. histolytica antigen vaccines is possible.
Zhang
T
T
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
Cieslak
P R
PR
Stanley
S L
SL
D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology*; D004748:Entamoeba histolytica / Q000276:immunology*; D005260:Female; D005849:Gerbillinae; D006968:Hypersensitivity, Delayed; D007114:Immunization; D008101:Liver Abscess, Amebic / Q000517:prevention & control*; D008565:Membrane Proteins / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology*; D016052:Protozoan Vaccines / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000276:immunology*
D000953:Antigens, Protozoan; D008565:Membrane Proteins; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D014614:Vaccines, Synthetic; C073020:serine-rich protein, Entamoeba histolytica