The causative agent of toxoplasmosis, Toxoplasma gondii (T. gondii), is able to influence the health of humans and other vertebrates. Toxoplasma may cause severe illness in the fetus and immunocompromised individuals. The high incidence and intense damages of Toxoplasma infection clearly shows the need to achieve the safe and suitable vaccine. In this study, an immunoinformatics approach was employed to design a multi-epitope DNA vaccine encoding the T. gondii SAG1, SAG3 and SAG5. The bioinformatic outputs supported the immunogenic and non-allergic natures of multi-epitope vaccine. Thereafter, the protective efficacy of the vaccine was evaluated with/without CpG-ODN adjuvant in a laboratory animal model. BALB/c mice were immunized subcutaneously with multi-epitope DNA vaccine. The in vivo findings indicated that the multi-epitope DNA vaccine elicited significant production of IgG antibodies (472.90 ± 2.74 ng/ml) as well as IFN-γ (173.71 ± 26.39 pg/ml) (p < 0.001). Moreover, a significant reduced parasite-burden (17,470 per mg of spleen) and prolonged survival time (9 days) were observed in the immunized groups compared to the controls (p < 0.05). The low values of IL-4 (22.5 ± 0.16 pg/ml) were detected in vaccinated mice compared to the control (PBS) (p > 0.05). In addition, CpG-ODN as an adjuvant increased the immune efficacy of the multi-epitope DNA vaccine. In multi-epitope vaccine+CpG-ODN group, the values of IgG antibodies (535.90 ±7.29 ng/ml) and IFN-γ (358.21 ± 32.70 pg/ml) were significanly higher than the multi-epitope vaccine group. Meanwhile, an increased survival time (10 days) and fewer parasite load (15,485 per mg of spleen) were observed in multi-epitope vaccine+CpG-ODN group. The results revealed that the DNA vaccine containing epitopes of SAG1, SAG3 and SAG5 adjuvanted with CpG-ODN might be a new model for further investigations against acute T. gondii infection.

弓形虫病的病原体弓形虫（弓形虫），是能够影响人类和其他脊椎动物的健康。弓形虫可能导致胎儿和免疫功能低下的人患严重疾病。弓形虫感染的高发率和严重破坏清楚地表明需要获得安全和合适的疫苗。在这项研究中，采用免疫信息学方法设计了编码弓形虫的多表位DNA疫苗。SAG1，SAG3和SAG5。生物信息学的输出支持多表位疫苗的免疫原性和非过敏性。此后，在实验室动物模型中评估有/无CpG-ODN佐剂时疫苗的保护功效。用多表位DNA疫苗皮下免疫BALB / c小鼠。的体内研究结果表明，多表位的DNA疫苗引发显著生产IgG抗体（472.90±2.74毫微克/毫升），以及IFN-γ（173.71±26.39微克/毫升）（p <0.001）。此外，与对照组相比，免疫组的寄生虫负担明显减少（每毫克脾脏17,470毫克），存活时间延长（9天）（p<0.05）。与对照（PBS）相比，接种疫苗的小鼠IL-4值低（22.5±0.16 pg / ml）（p > 0.05）。另外，CpG-ODN作为佐剂增加了多表位DNA疫苗的免疫效力。在多表位疫苗+ CpG-ODN组中，IgG抗体（535.90±7.29 ng / ml）和IFN-γ（358.21±32.70 pg / ml）的值明显高于多表位疫苗组。同时，在多表位疫苗+ CpG-ODN组中观察到了更长的生存时间（10天）和更少的寄生虫负荷（15,485 / mg脾脏）。结果表明，含有佐剂CpG-ODN的SAG1，SAG3和SAG5抗原决定簇的DNA疫苗可能是进一步研究急性弓形虫感染的新模型。