title: MIC3, a novel cross-protective antigen expressed in Toxoplasma gondii and Neospora caninum.
abstract: Microneme protein 3 (MIC3) is an important adhesion molecule expressed by Toxoplasma gondii and Neospora caninum that plays a crucial role in invasion. In our study, we found that recombinant TgMIC3 (rTgMIC3) was recognized by both T. gondii-reactive sera and hyper-immune serum against N. caninum. Polyclonal antibodies against TgMIC3 reacted with N. caninum by western blot and immunofluorescence assay (IFA). These results indicate that MIC3 is a novel cross-reactive antigen expressed in N. caninum and T. gondii. To evaluate the immune-protective effect of TgMIC3, we created the eukaryotic expression vector pcDNA3.1-TgMIC3, transfected this vector into HEK293T cells by lipofection, and evaluated TgMIC3 expression in HEK293T cells using western blot and IFA. Then, groups of BALB/c mice were immunized with recombinant TgMIC3 protein, pcDNA3.1-TgMIC3, or two-vaccine immunization. The mice were challenged with T. gondii RH or N. caninum Nc-1 tachyzoites 14 days after the final immunization. The survival time of T. gondii-infected mice was recorded, and the parasite burden in the brain of N. caninum-infected mice 30 days post-infection was measured using real-time PCR. The results demonstrated that mice immunized with TgMIC3-based vaccines elicited high antibody titers. After parasitic challenge, mice immunized with pcDNA-TgMIC3 exhibited prolonged survival when infected with T. gondii tachyzoites and a lower parasitic burden in the brains of mice challenged with N. caninum tachyzoites. These results demonstrate that TgMIC3 is a cross-protective antigen expressed in T. gondii and N. caninum and could elicit some protection against toxoplasmosis and neosporosis.
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, Beijing, China.
authors.forename: Daoyu
authors.initials: D
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Pan
authors.initials: P
authors.lastname: Hao
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Lei
authors.forename: Dan
authors.initials: D
authors.lastname: Shan
authors.forename: Qun
authors.initials: Q
authors.lastname: Liu
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D001921:Brain / Q000469:parasitology; D003429:Cross Reactions; D016207:Cytokines / Q000378:metabolism; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D018688:Neospora / Q000276:immunology / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016052:Protozoan Vaccines / Q000276:immunology*; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000276:immunology; D014122:Toxoplasma / Q000276:immunology / Q000378:metabolism*; D014123:Toxoplasmosis / Q000276:immunology / Q000517:prevention & control*; D014611:Vaccination
chemical_list: D000953:Antigens, Protozoan; D016207:Cytokines; C421382:MIC3 protein, Toxoplasma gondii; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D011994:Recombinant Proteins