title: Protective immunity induced by Toxoplasma gondii rhoptry protein 16 against toxoplasmosis in mice.
abstract: Toxoplasma gondii can infect a large variety of domestic and wild animals and human beings, sometimes causing severe pathology. Rhoptries are involved in T. gondii invasion and host cell interaction and have been implicated as important virulence factors. In this study, we constructed a DNA vaccine expressing rhoptry protein 16 (ROP16) of T. gondii and evaluated the immune responses it induced in Kunming mice. The gene sequence encoding ROP16 was inserted into the eukaryotic expression vector pVAX I. We immunized Kunming mice intramuscularly. After immunization, we evaluated the immune response using a lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally. The results showed that mice immunized with pVAX-ROP16 developed a high level of specific antibody responses against T. gondii ROP16 expressed in Escherichia coli, a strong lymphoproliferative response, and significant levels of gamma interferon (IFN-γ), interleukin-2 (IL-2), IL-4, and IL-10 production compared with results for other mice immunized with either empty plasmid or phosphate-buffered saline, respectively. The results showed that pVAX-ROP16 induces significant humoral and cellular Th1 immune responses. After lethal challenge, the mice immunized with pVAX-ROP16 showed a significantly (P < 0.05) prolonged survival time (21.6 ± 9.9 days) compared with control mice, which died within 7 days of challenge. Our data demonstrate, for the first time, that ROP16 triggers a strong humoral and cellular response against T. gondii and that ROP16 is a promising vaccine candidate against toxoplasmosis, worth further development.
authors.affiliation: Department of Parasitology, 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: Xian-Hui
authors.initials: XH
authors.lastname: He
authors.forename: Eskild
authors.initials: E
authors.lastname: Petersen
authors.forename: Dong-Hui
authors.initials: DH
authors.lastname: Zhou
authors.forename: Yong
authors.initials: Y
authors.lastname: He
authors.forename: Rui-Qing
authors.initials: RQ
authors.lastname: Lin
authors.forename: Xiu-Zhen
authors.initials: XZ
authors.lastname: Li
authors.forename: Xu-Li
authors.initials: XL
authors.lastname: Chen
authors.forename: Xiao-Ru
authors.initials: XR
authors.lastname: Shi
authors.forename: Xiu-Ling
authors.initials: XL
authors.lastname: Zhong
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Xing-Quan
authors.initials: XQ
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000918:Antibody Specificity; D005260:Female; D006801:Humans; D007114:Immunization; D008213:Lymphocyte Activation; D051379:Mice; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D014122:Toxoplasma / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000276:immunology / Q000517:prevention & control*; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D019444:Vaccines, DNA; D011505:Protein-Tyrosine Kinases; C552524:Rop16 protein, Toxoplasma gondii