Department of Medical Parasitology and Mycology, Children Growth Research Center, Research Institute for Prevention of Non-Communicable Diseases, Qazvin University of Medical Sciences, Qazvin, Iran; Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran.
Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
Microb Pathog. 2021 Apr;153:104764. doi: 10.1016/j.micpath.2021.104764. Epub 2021 Feb 3.
Toxoplasma gondii is an intracellular apicomplexan parasite, which can cause a serious infectious disease in pregnant women and immunocompromised individuals. Therefore, the development of a polyvalent vaccine consisting of all stages of the parasite life cycle using the epitopes from tachyzoites, bradyzoites, and sporozoites is likely to be required for complete protective immunity. In this study, we designed protein vaccine candidate based on the prediction of specific epitopes (i.e., B cell and T cell) from three Toxoplasma gondii antigens. The MRS protein (MIC3: 30-180, ROP8: 85-185, and SAG1: 85-235) was expressed in Escherichia coli, and purification was performed using a HisTrap HP column and then we evaluated immunogenicity and protective property in BALB/c mice. Seventy-two mice were randomly divided into six groups, including three vaccinations (i.e., MRS, MRS-Freund, and MRS-Calcium Phosphate Nanoparticles (MRS-CaPNs)) and three control (i.e., Phosphate-buffered saline, Freund, and CaPNs) groups. All groups were immunized three times via subcutaneous injection within three-week intervals. In the vaccination groups, the BALB/c mice were injected with 20 μg of MRS protein for the first time and 10 μg of MRS for the next two times. Antibodies, cytokines, and splenocytes proliferation in the immunized mice were assayed using the enzyme-linked immunosorbent assay. Protective efficacy was analyzed by challenging the immunized mice with T. gondii of RH strain. Antibody, cytokine, and lymphocyte proliferation assays showed that the mice immunized with MRS induced stronger humoral and T helper type 1 cell-mediated immune responses, compared to the control mice. However, co-immunization with adjuvants (i.e., Freund and CaNPs) resulted in impaired immune responses. Effective protection against the parasite achieved an increase in survival time in the immunized mice, especially in the MRS-CaNPs group. The obtained results of the present study demonstrated that multi-epitope protein vaccination, MRS, is a potential strategy against toxoplasmosis infection. In addition, the vaccine co-delivered with CaPNs could provide an important key for vaccine candidate to control T. gondii infection.
刚地弓形虫是一种细胞内顶复门原虫寄生虫，可导致孕妇和免疫功能低下者发生严重的传染病。因此，使用速殖子、缓殖子和裂殖子的各阶段寄生虫生活史的表位，开发多价疫苗以提供完全的保护性免疫可能是必要的。在这项研究中，我们根据三个弓形虫抗原的特定表位（即 B 细胞和 T 细胞）的预测，设计了蛋白疫苗候选物。MRS 蛋白（MIC3：30-180、ROP8：85-185 和 SAG1：85-235）在大肠杆菌中表达，并使用 HisTrap HP 柱进行纯化，然后我们在 BALB/c 小鼠中评估了其免疫原性和保护特性。72 只小鼠被随机分为 6 组，包括 3 次免疫（即 MRS、MRS-Freund 和 MRS-磷酸钙纳米颗粒（MRS-CaPNs））和 3 次对照（即磷酸盐缓冲盐水、Freund 和 CaPNs）。所有组均在 3 周间隔内通过皮下注射进行 3 次免疫。在接种组中，BALB/c 小鼠首次注射 20 μg MRS 蛋白，接下来两次注射 10 μg MRS。通过酶联免疫吸附试验检测免疫小鼠的抗体、细胞因子和脾细胞增殖。通过用 RH 株弓形虫攻击免疫小鼠来分析保护效力。抗体、细胞因子和淋巴细胞增殖试验表明，与对照小鼠相比，用 MRS 免疫的小鼠诱导了更强的体液和辅助性 T 细胞 1 型细胞介导的免疫应答。然而，与佐剂（即 Freund 和 CaNPs）共同免疫导致免疫应答受损。有效保护免受寄生虫感染可延长免疫小鼠的存活时间，尤其是在 MRS-CaNPs 组。本研究的结果表明，多表位蛋白疫苗 MRS 是一种针对弓形虫感染的潜在策略。此外，与 CaPNs 共同递送的疫苗为控制弓形虫感染的疫苗候选物提供了重要关键。
