quillaja-saponins and Toxoplasmosis--Animal

We evaluated the humoral and cellular immune responses in pigs immunized intranasally with crude rhoptry proteins of Toxoplasma gondii plus Quil-A. The experiment used 13 mixed-breed pigs divided into the following three groups: G1 (vaccinated-challenged, n=6), which received the rhoptry vaccine (200(g/dose); G2 (adjuvant-challenged, n=4), which received PBS plus Quil-A; and G3 (unvaccinated-challenged, n=3), which was the control group. The treatments were performed intranasally at days 0, 21, and 42. Three pigs from G1 produced IgG and IgM antibody levels above the cut-off in the ELISA on the challenge day. Partial protection was observed in G1 at the chronic phase of infection when compared with G3. The preventable fractions were 41.6% and 6.5%, in G1 and G2, respectively. The results of this study suggest that rhoptry proteins plus Quil-A stimulated humoral, local, and systemic immune responses, which were able to partially protect the brain from cyst formation.

Topics: Adjuvants, Immunologic; Administration, Intranasal; Animals; Brain; Cell Proliferation; Immunity, Cellular; Immunity, Humoral; Immunoglobulin G; Immunoglobulin M; Lymphocytes; Mice; Protozoan Proteins; Protozoan Vaccines; Quillaja Saponins; Saponins; Swine; Swine Diseases; Toxoplasma; Toxoplasmosis, Animal

Topics: Adjuvants, Immunologic; Animals; Antibodies, Protozoan; Antigens, Protozoan; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; DNA; Female; Immunoglobulin G; Interferon-gamma; Protozoan Proteins; Protozoan Vaccines; Quillaja Saponins; Swine; Toxoplasma; Toxoplasmosis, Animal; Vaccination

Surface antigen 3 (SAG3) of Toxoplasma gondii is very similar in structure to the major surface antigen 1 (SAG1). Although numerous studies have supported the importance of SAG1 in protection against T. gondii infection, few reports exist on SAG3.. Glutathione-S-transferase (GST)-fused SAG3 of T. gondii (rSAG3) were immunized into BALB/c mice alone or in combination with Quil A (rSAG3/Quil A), and then evaluated the protective immunity in vivo and in vitro against murine toxoplasmosis.. Immunization with rSAG3 or rSAG3/Quil A resulted in significantly more survival days and fewer brain cysts after challenge with T. gondii compared to an infected control group. Mice immunized with rSAG3 alone or in combination with Quil A produced significantly more specific IgG2a antibody, whereas specific IgG1 antibody titers did not increase. The percentage of CD8+ T cells, IFN-gamma mRNA expression, and nitric oxide production significantly increased in rSAG3- and rSAG3/Quil A-immunized mice.. These results indicate that vaccination with Toxoplasma rSAG3 results in partial protective immunity against T. gondii infection through induction of a Th1-type immune response, and that protective immunity is accelerated by the modulating effects of Quil A.

Topics: Animals; Antigens, Protozoan; Bacterial Proteins; Blotting, Western; Enzyme-Linked Immunosorbent Assay; Female; Flow Cytometry; Immunoglobulin G; Interferon-gamma; Mice; Mice, Inbred BALB C; Nitric Oxide; Protozoan Proteins; Quillaja Saponins; Recombinant Fusion Proteins; Reverse Transcriptase Polymerase Chain Reaction; Saponins; Toxoplasma; Toxoplasmosis, Animal; Vaccination

Induction of protective immunity against acute and chronic toxoplasmosis can be achieved using p30, the major membrane and excreted/secreted protein of Toxoplasma gondii. This protein, when administered to outbred mice in the presence of the saponin Quil A, is able to induce almost 100% protection against acute infection without evidence of intracerebral cyst development. Adoptive transfer of immune splenocytes from immunized inbred A/J mice conferred a significant level (p less than 0.001) of protection against subsequent challenge. Phenotypic analysis in outbred as well as two different strains of inbred mice (A/J and C57BL/6) demonstrated that CD8+ T cells are selectively stimulated by this immunization protocol. T cell depletion studies using specific mAb directed at either CD3+ or CD8+ T cell phenotype, followed by adoptive transfer, failed to confer protective immunity, whereas CD4+ depletion had no effect. These cytotoxic CD8+ T cells produced high titers of both IFN-gamma and IL-2. Moreover, these CD8+ T cells were directly parasiticidal against radiolabeled extracellular T. gondii, further supporting the critical immune function of these p30 Ag-specific CD8+ T cells in host immunity against T. gondii infection.

Topics: Adjuvants, Immunologic; Animals; Antigens, Protozoan; CD8 Antigens; Cytotoxicity, Immunologic; Immunity, Cellular; Immunization, Passive; Interferon-gamma; Interleukin-2; Mice; Protozoan Proteins; Quillaja Saponins; Saponins; T-Lymphocyte Subsets; Toxoplasma; Toxoplasmosis, Animal