title: Protective effect against toxoplasmosis in mice induced by DNA immunization with gene encoding Toxoplasma gondii ROP18.
abstract: Toxoplasma gondii is an obligate intracellular protozoan parasite infecting mammals and birds including humans. Rhoptry protein 18 has been implicated as an important virulence factor. In this study, we constructed a DNA vaccine expressing rhoptry protein 18 (ROP18) of T. gondii, and evaluated the immune response and protective immunity in Kunming mice. The gene sequence encoding ROP18 was inserted into the eukaryotic expression vector pVAX I. Intramuscular immunization of mice with pVAX-ROP18 elicited specific humoral responses and stimulated lymphoproliferation (P<0.05). The cellular immune response was associated with the production of IFN-γ, indicating that a Th1 type response was elicited, which was confirmed by the production of large amounts of IgG2a (P<0.05). By the expression of the CD69, an activation marker of CD4+ and CD8+ T cells, we found that pVAX-ROP18 enhanced the activation of CD4+ and CD8+ T cells in lymphoid in mice. After lethal challenge, the mice immunized with the pVAX-ROP18 showed a significantly increased survival time (27.9±15.1 days) compared with control mice which died within 7 days of challenge (P<0.05). Our results show for the first time, that a ROP18 vaccine construct can enhance the T. gondii-specific CTL. Th1 responses and increased survival suggested that ROP18 is a promising vaccine candidate against infection with T. gondii.
authors.affiliation: State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, PR China.
authors.forename: Zi-Guo
authors.initials: ZG
authors.lastname: Yuan
authors.forename: Xiu-Xiang
authors.initials: XX
authors.lastname: Zhang
authors.forename: Rui-Qing
authors.initials: RQ
authors.lastname: Lin
authors.forename: Eskild
authors.initials: E
authors.lastname: Petersen
authors.forename: Shenyi
authors.initials: S
authors.lastname: He
authors.forename: Miao
authors.initials: M
authors.lastname: Yu
authors.forename: Xian-Hui
authors.initials: XH
authors.lastname: He
authors.forename: Dong-Hui
authors.initials: DH
authors.lastname: Zhou
authors.forename: Yong
authors.initials: Y
authors.lastname: He
authors.forename: Hao-Xin
authors.initials: HX
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Liao
authors.forename: Xing-Quan
authors.initials: XQ
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D049109:Cell Proliferation; D004195:Disease Models, Animal; D005260:Female; D007074:Immunoglobulin G / Q000097:blood; D007273:Injections, Intramuscular; D007371:Interferon-gamma / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000276:immunology; D051379:Mice; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D012376:Rodent Diseases / Q000517:prevention & control; D016019:Survival Analysis; D014124:Toxoplasmosis, Animal / Q000517:prevention & control*; D014611:Vaccination / Q000379:methods*; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D019444:Vaccines, DNA; D007371:Interferon-gamma; D017346:Protein Serine-Threonine Kinases; C556793:ROP18 protein, Toxoplasma gondii