The protective effect of a Toxoplasma gondii SAG1 plasmid DNA vaccine in mice is enhanced with IL-18.
More effective vaccines against Toxoplasma gondii may contribute to the control of this pathogen that has major veterinary and public health significance. In this study, two recombinant plasmids pcDNA/TgSAG1 and pVAX/mIL-18 containing T. gondii SAG1 (TgSAG1) and murine cytokine interleukin-18 (IL-18) were evaluated for their ability to protect mice against T. gondii challenge. Mice were given two intramuscular immunizations 3 weeks apart, and challenged with T. gondii 3 weeks later. All animals vaccinated with pcDNA/TgSAG1 alone or with pVAX/mIL-18 developed specific anti-TLA (T. gondii lysate antigen) antibodies and specific lymphocyte proliferative responses. Co-injection of pVAX/mIL-18 significantly increased the production of IFN-gamma and IL-2. Further, challenge experiments showed that co-immunization with pVAX/mIL-18 significantly (P<0.05) increased the survival rate (60%), compared with pcDNA/TgSAG1 alone (40%). Therefore, codelivery of the IL-18-secreting plasmid potentiates the induction and maintenance of the type 1 helper T-cell immune response and may be a potent strategy for enhancing the protective efficacy of vaccines against T. gondii.
Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun 130062, Jilin Province, China. liuquan1973@hotmail.com
Quan
Q
Liu
Limin
L
Shang
Hongtao
H
Jin
Feng
F
Wei
Xing-Quan
XQ
Zhu
Hongwei
H
Gao
D000276:Adjuvants, Immunologic; D000818:Animals; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan / Q000276:immunology*; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D020382:Interleukin-18 / Q000008:administration & dosage / Q000276:immunology*; D051379:Mice; D010957:Plasmids / Q000276:immunology; D015800:Protozoan Proteins / Q000276:immunology*; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000276:immunology*; D013154:Spleen / Q000166:cytology; D014122:Toxoplasma; D014124:Toxoplasmosis, Animal / Q000517:prevention & control*; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*
D000276:Adjuvants, Immunologic; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016207:Cytokines; D020382:Interleukin-18; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; C047168:SAG1 antigen, Toxoplasma; D019444:Vaccines, DNA