Department of Pathogenic Biology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu, China.
Department of Gastroenterology, West China Hospital of Sichuan University, Chengdu, China.
Immunobiology. 2021 May;226(3):152085. doi: 10.1016/j.imbio.2021.152085. Epub 2021 Mar 27.
The most dangerous form of leishmaniasis is Visceral leishmaniasis (VL). The elimination of VL depends not only on agent treatments but also on effective vaccines against Leishmania parasites. Epitope-based vaccines composed of alternative short antigenic epitopes have the advantages of MHC epitope easy designing, which has broad application prospects. In a previous study, we analyzed Leishmania Gp63, Kmp-11 and Amastin protein sequence in silico, and found that the amino acid fragments of Gp63 (138-360aa), Kmp-11 (1-91aa) and Amastin (1-72aa) were rich in dominant epitopes. In this study, we used the three amino acid fragments as multi-epitope vaccine candidates to construct DNA and protein vaccines. BALB/c mice were vaccinated with the DNA and protein vaccines by DNA prime-protein boost strategy and challenged with Leishmania promastigotes. To evaluate vaccine immunogenicity and immunoprotection, serum specific antibody titers and cytokines were detected using ELISA, splenic CD3, CD4 and CD8 cells were analyzed by flow cytometry, livers were made into pathological sections to observe pathological changes, and splenic parasitic loads were quantified using qPCR. The results showed that the increased specific IgG titers from vaccinated mice supported the vaccine immunogenicity. The increased cytokines (IFN-γ, IL-12 and TNF-α), splenic CD3, CD4 and CD8 T cells and hepatic granulomas, and the decreased splenic parasitic loads (parasite reduction rates of Gp63, Kmp-11 and Amatin groups were 89%, 86% and 79%, respectively) from immunized mice post-infection were suggested the good immunoprotection of the vaccines. Our study demonstrated that vaccines based on the dominant epitopes of Gp63, Kmp-11 and Amastin with DNA prime-protein boost vaccination strategy showed significant immune effects against Leishmania, especially the Gp63 group showed a nearly 90% parasites reduction rate. This study will provide references for visceral leishmaniasis epitope vaccine design and immune strategy selection.
利什曼病最危险的形式是内脏利什曼病（VL）。VL 的消除不仅取决于药物治疗，还取决于针对利什曼寄生虫的有效疫苗。基于表位的疫苗由替代的短抗原表位组成，具有 MHC 表位易于设计的优点，具有广阔的应用前景。在之前的一项研究中，我们对利什曼 Gp63、Kmp-11 和 Amastin 蛋白序列进行了计算机分析，发现 Gp63（138-360aa）、Kmp-11（1-91aa）和 Amastin（1-72aa）的氨基酸片段富含优势表位。在这项研究中，我们使用这三个氨基酸片段作为多表位疫苗候选物来构建 DNA 和蛋白质疫苗。BALB/c 小鼠通过 DNA 初免-蛋白加强策略用 DNA 和蛋白疫苗进行免疫接种，并受到利什曼前鞭毛体的挑战。为了评估疫苗的免疫原性和免疫保护作用，通过 ELISA 检测血清特异性抗体滴度和细胞因子，通过流式细胞术分析脾 CD3、CD4 和 CD8 细胞，制作肝病理切片观察病理变化，并用 qPCR 定量脾寄生载量。结果表明，来自接种疫苗的小鼠的特异性 IgG 滴度增加支持了疫苗的免疫原性。增加的细胞因子（IFN-γ、IL-12 和 TNF-α）、脾 CD3、CD4 和 CD8 T 细胞和肝肉芽肿，以及脾寄生载量的减少（Gp63、Kmp-11 和 Amatin 组的寄生虫减少率分别为 89%、86%和 79%）表明疫苗具有良好的免疫保护作用。我们的研究表明，基于 Gp63、Kmp-11 和 Amastin 的优势表位的疫苗与 DNA 初免-蛋白加强接种策略联合使用，对利什曼病具有显著的免疫效果，特别是 Gp63 组的寄生虫减少率接近 90%。这项研究将为内脏利什曼病表位疫苗设计和免疫策略选择提供参考。
