title: Toxoplasma gondii: protective immunity against experimental toxoplasmosis induced by a DNA vaccine encoding the perforin-like protein 1.
abstract: Toxoplasma gondii is an important zoonotic parasite infecting about one third of the world population, causing congenital infections and eye disease. T. gondii perforin-like protein 1 (TgPLP1) is believed to be involved in the acute virulence of T. gondii in mice, and is therefore of interest as a vaccine candidate. In this study, we constructed a DNA vaccine expressing TgPLP1, and evaluated the immune response in Kunming mice. The gene sequence encoding TgPLP1 was inserted into the eukaryotic expression vector pVAX I, and Kunming mice were immunized intramuscularly with the plasmid. After immunization, we evaluated the immune response using lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally with 1×10(3) tachyzoites of the virulent T. gondii RH strain. The results showed that pVAX/TgPLP1 alone or with pVAX/IL-18 developed specific anti-TLA (T. gondii lysate antigen) antibodies and specific lymphocyte proliferative responses. Co-injection of pVAX/IL-18 significantly increased the production of IFN-γ and IL-2. Further, challenge experiments showed that co-immunization of pVAX/TgPLP1 with pVAX/IL-18 significantly (P<0.05) increased survival time (12.7±1.2days) of immunized mice, compared with pVAX/TgPLP1 alone (11.3±0.9days). These results demonstrate that TgPLP1 is a potential vaccine candidate against toxoplasmosis, worth further evaluation in other animal hosts. IL-18 could enhance the immune effect of TgPLP1, prolonging the survival time of immunized mice.
authors.affiliation: College of Veterinary Medicine, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong, PR China.
authors.forename: Hai-Kuo
authors.initials: HK
authors.lastname: Yan
authors.forename: Zi-Guo
authors.initials: ZG
authors.lastname: Yuan
authors.forename: Eskild
authors.initials: E
authors.lastname: Petersen
authors.forename: Xiu-Xiang
authors.initials: XX
authors.lastname: Zhang
authors.forename: Dong-Hui
authors.initials: DH
authors.lastname: Zhou
authors.forename: Quan
authors.initials: Q
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: He
authors.forename: Rui-Qing
authors.initials: RQ
authors.lastname: Lin
authors.forename: Min-Jun
authors.initials: MJ
authors.lastname: Xu
authors.forename: Xu-Li
authors.initials: XL
authors.lastname: Chen
authors.forename: Xiu-Ling
authors.initials: XL
authors.lastname: Zhong
authors.forename: Xing-Quan
authors.initials: XQ
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D016207:Cytokines / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D007074:Immunoglobulin G / Q000097:blood; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains; D054353:Perforin / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D016052:Protozoan Vaccines / Q000235:genetics; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000166:cytology / Q000276:immunology; D014122:Toxoplasma / Q000235:genetics / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000276:immunology / Q000517:prevention & control*; D014162:Transfection; D019444:Vaccines, DNA
chemical_list: D000913:Antibodies, Protozoan; D016207:Cytokines; D007074:Immunoglobulin G; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D019444:Vaccines, DNA; C534951:perforin-like protein 1, Toxoplasma gondii; D054353:Perforin