Abstract: Objective To construct the eukaryotic expression vector of rhoptry protein 7 (ROP7) of Toxoplasma gondii and to evaluate the protective effect induced by recombinant plasmid on mice. Methods PCR primers were designed based on the ROP7 sequence of Toxoplasma gondii in Genbank. The ROP7 gene was amplified by PCR and inserted into the eukaryotic vector pEGFP-C1 and the recombinant plasmid pEGFP-C1/ROP7 (pROP7) was constructed. Then the plasmids were transfected into HEK293T cells to verify the expression in eukaryotic cells. A total of 36 female BALB/c mice were randomly divided into three groups: phosphate buffer saline (PBS) control group, pEGFP-C1 control group and the pROP7 experimental group. Then PBS, pEGFP-C1 and pROP7 were used to immunize the corresponding group of mice respectively. The special serum IgG level was detected with ELISA and the survival time of challenged mice was recorded to evaluate the immune protection. Results The target gene (1728bp) was successfully amplified by PCR. The recombinant plasmid was successfully constructed and expressed in HEK293T cells. Its protein was recognized with a goat anti-Toxopasma gondii antibody. Mice immunized with the recombinant plasmid produced high levels of serum antibodies. In the challenge experiment, the survival time of mice in pROP7 experience group was significantly prolonged compared with that of control groups (P <0.05). Conclusion With the immunological effect of this expressed recombinant plasmid, the present study might provide reference for future study of DNA vaccine against Toxoplasma gondii.

Key words: DNA vaccine, Toxoplasma gondii, Immunoprotective, ROP7