Vaccination against murine toxoplasmosis using recombinant Toxoplasma gondii SAG3 antigen alone or in combination with Quil A.
OBJECTIVE
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Lee
Young-Ha
YH
Department of Infection Biology, College of Medicine, Chungnam National University, 6 Munwha-dong, Jung-gu, Daejeon 301-131, Korea. yhalee@cnu.ac.kr
Shin
Dae-Whan
DW
Lee
Jae-Ho
JH
Nam
Ho-Woo
HW
Ahn
Myoung-Hee
MH
D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D007074:Immunoglobulin G / Q000276:immunology; D007371:Interferon-gamma / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D062605:Quillaja Saponins; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012503:Saponins / Q000276:immunology*; D014122:Toxoplasma / Q000254:growth & development / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D014611:Vaccination / Q000379:methods*
D000953:Antigens, Protozoan; D001426:Bacterial Proteins; D007074:Immunoglobulin G; D015800:Protozoan Proteins; D062605:Quillaja Saponins; D011993:Recombinant Fusion Proteins; D012503:Saponins; D009569:Nitric Oxide; C046386:Quil A; D007371:Interferon-gamma