title: Protection against toxoplasmosis in mice immunized with different antigens of Toxoplasma gondii incorporated into liposomes.
abstract: Different toxoplasma antigens were entrapped within liposomes and evaluated, in this form, for their ability to protect Swiss mice against toxoplasma infection: soluble tachyzoite antigen (L/TAg), tissue cyst (L/CAg), tachyzoite plus tissue cyst (L/TCAg) or purified antigen of tachyzoite (L/pTAg). The protein used in L/pTAg was purified from tachyzoites using a stage-specific monoclonal antibody which reacted at a molecular weight of 32 kD in SDS PAGE and silver stain using reduced condition. To compare the immuno-adjuvant action of liposomes and of Freund's Complete Adjuvant (FCA), another group of mice was immunized with soluble tachyzoite antigen (STAg) emulsified in FCA (FCA/TAg). Control groups were inoculated with (STAg) alone, phosphate-buffered saline (PBS), FCA with PBS (FCA/PBS) and empty liposomes (L/PBS). Mice were inoculated subcutaneously with these antigens six, four and two weeks before a challenge with 80 tissue cysts of the P strain of Toxoplasma gondii orally. All mice immunized with or without adjuvant showed a humoral response, as measured by Elisa. However, no correlation was found between antibody titer and protection against the challenge. All mice immunized with L/pTAg or L/TCAg survived (100), whereas 80% and 90% of mice from groups which received respectively PBS or FCA/PBS and L/PBS died. All mice immunized with antigens entrapped within liposomes (L/TAg, L/CAg, L/TCAg and L/pTAg) showed low numbers of intracerebral cysts.
authors.affiliation: Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 31270-901, Brasil.
authors.forename: M M
authors.initials: MM
authors.lastname: Elsaid
authors.forename: R W
authors.initials: RW
authors.lastname: Vitor
authors.forename: F J
authors.initials: FJ
authors.lastname: Frézard
authors.forename: M S
authors.initials: MS
authors.lastname: Martins
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan / Q000008:administration & dosage* / Q000302:isolation & purification; D004306:Dose-Response Relationship, Immunologic; D004337:Drug Carriers; D005260:Female; D008081:Liposomes; D051379:Mice; D015800:Protozoan Proteins / Q000276:immunology*; D016052:Protozoan Vaccines / Q000276:immunology*; D014122:Toxoplasma / Q000276:immunology* / Q000302:isolation & purification; D014123:Toxoplasmosis / Q000276:immunology / Q000517:prevention & control*
chemical_list: D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan; D004337:Drug Carriers; D008081:Liposomes; D015800:Protozoan Proteins; D016052:Protozoan Vaccines