title: Protective efficacy of a Toxoplasma gondii rhoptry protein 13 plasmid DNA vaccine in mice.
abstract: Toxoplasma gondii is an obligate intracellular parasite infecting humans and other warm-blooded animals, resulting in serious public health problems and economic losses worldwide. Rhoptries are involved in T. gondii invasion and host cell interaction and have been implicated as important virulence factors. In the present study, a DNA vaccine expressing rhoptry protein 13 (ROP13) of T. gondii inserted into eukaryotic expression vector pVAX I was constructed, and the immune protection it induced in Kunming mice was evaluated. Kunming mice were immunized intramuscularly with pVAX-ROP13 and/or with interleukin-18 (IL-18). Then, we evaluated the immune response using a lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged with the virulent T. gondii RH strain (type I) and the cyst-forming PRU strain (type II). The results showed that pVAX-ROP13 alone or with pVAX/IL-18 induced a high level of specific anti-T. gondii antibodies and specific lymphocyte proliferative responses. Coinjection of pVAX/IL-18 significantly increased the production of gamma interferon (IFN-γ), IL-2, IL-4, and IL-10. Further, challenge experiments showed that coimmunization of pVAX-ROP13 with pVAX/IL-18 significantly (P < 0.05) increased survival time (32.3 ± 2.7 days) compared with pVAX-ROP13 alone (24.9 ± 2.3 days). Immunized mice challenged with T. gondii cysts (strain PRU) had a significant reduction in the number of brain cysts, suggesting that ROP13 could trigger a strong humoral and cellular response against T. gondii cyst infection and that it is a potential vaccine candidate against toxoplasmosis, which provided the foundation for further development of effective vaccines against T. gondii.
authors.affiliation: State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, People's Republic of China.
authors.forename: Pei-Yuan
authors.initials: PY
authors.lastname: Wang
authors.forename: Zi-Guo
authors.initials: ZG
authors.lastname: Yuan
authors.forename: Eskild
authors.initials: E
authors.lastname: Petersen
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Xiu-Xiang
authors.initials: XX
authors.lastname: Zhang
authors.forename: Xiu-Zhen
authors.initials: XZ
authors.lastname: Li
authors.forename: Hao-Xin
authors.initials: HX
authors.lastname: Li
authors.forename: Zhi-Cheng
authors.initials: ZC
authors.lastname: Lv
authors.forename: Tian
authors.initials: T
authors.lastname: Cheng
authors.forename: Di
authors.initials: D
authors.lastname: Ren
authors.forename: Gui-Lian
authors.initials: GL
authors.lastname: Yang
authors.forename: Rui-Qing
authors.initials: RQ
authors.lastname: Lin
authors.forename: Xing-Quan
authors.initials: XQ
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D001921:Brain / Q000469:parasitology; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D015870:Gene Expression; D005822:Genetic Vectors; D007273:Injections, Intramuscular; D007963:Leukocytes, Mononuclear / Q000276:immunology; D051379:Mice; D059208:Parasite Load; D010957:Plasmids; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014122:Toxoplasma / Q000235:genetics / Q000276:immunology*; D014123:Toxoplasmosis / Q000469:parasitology / Q000517:prevention & control; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D037521:Virulence Factors / Q000235:genetics / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D016207:Cytokines; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D019444:Vaccines, DNA; D037521:Virulence Factors