Data_Sheet_6_Immuno-informatics Analysis to Identify Novel Vaccine Candidates and Design of a Multi-Epitope Based Vaccine Candidate Against Theileria parasites.XLSX

Theileriosis poses a serious threat to ruminants in tropical and subtropical countries. It is a tick-borne disease, caused by an apicomplexan parasite, Theileria. The high disease burden in animals causes huge economic losses to marginal farmers. Further, with increasing cases of resistance to commonly used drugs, it is highly desirable to develop better and cost-effective vaccines against theileriosis. The only available vaccine, live attenuated parasite vaccine, has many drawbacks and hence is unsuitable for controlling this disease. Immuno-informatics has emerged as a useful tool in down selection of potential molecules for vaccine development. In this study, we have used an immuno-informatics driven genome-wide screening strategy to identify potential vaccine targets containing important and effective dominant immunogens against Theileria. The proteome of Theileria annulata was screened for proteins with probability of plasma membrane localization or GPI anchor. The proteins non-homologous to the host (bovine) were selected and their antigenicity was analyzed. The B-cell epitopes were identified in the selected proteins and mapped in the modeled structure of the proteins. A total of 19 linear epitopes in 12 proteins, exposed in the extracellular space and having the potential to induce protective antibodies were obtained. Additionally, CTL epitopes which are peptides with 9-mer core sequence, were also identified, modeled and docked with bovine MHC-I structures. The CTL epitopes showing high binding energy with the bovine MHC-I were further engineered in silico to design a putative multi-epitope vaccine candidate against Theileria parasites. The docking studies and molecular dynamics studies with the predicted multi-epitope vaccine candidate and modeled bovine TLR4 exhibited strong binding energy, suggesting that the complex is stable and the putative multi-epitope vaccine candidate can be a potentially good candidate for vaccine development.

泰勒虫病（Theileriosis）对热带及亚热带地区的反刍动物构成严重威胁。该病为蜱传疾病，由顶复门寄生虫泰勒虫（Theileria）引发。动物感染该病所带来的沉重疾病负担，给边缘农户造成了巨额经济损失。此外，随着常用药物耐药性病例的逐年增多，研发更为优质且经济高效的泰勒虫病疫苗已成为迫切需求。
目前唯一可用的疫苗为活减毒寄生虫疫苗，但存在诸多缺陷，因此不适用于该病的防控工作。
免疫信息学已成为疫苗研发过程中筛选潜在靶点分子的有效工具。本研究采用免疫信息学驱动的全基因组筛选策略，旨在鉴定出可用于抗泰勒虫疫苗研发的、包含重要有效优势免疫原的潜在靶点。
本研究对环形泰勒虫（Theileria annulata）的蛋白质组进行筛选，寻找具备质膜定位可能性或糖基磷脂酰肌醇（GPI）锚定特征的蛋白质。
筛选出与宿主（牛）无同源性的蛋白质，并对其抗原性开展分析。
在筛选得到的蛋白质中鉴定B细胞表位，并将表位映射至该蛋白质的建模结构中。最终在12种蛋白质中获得19个线性表位，这些表位暴露于细胞外空间，且具备诱导保护性抗体产生的潜力。
此外，本研究还鉴定了以9聚体核心序列构成的细胞毒性T淋巴细胞（Cytotoxic T Lymphocyte, CTL）表位，对其进行建模后与牛主要组织相容性复合体I类（MHC-I）结构开展分子对接。与牛MHC-I结合亲和力较高的CTL表位，进一步通过计算机模拟进行工程化改造，以构建针对泰勒虫的候选多表位疫苗。
对预测得到的多表位候选疫苗与建模后的牛Toll样受体4（TLR4）进行分子对接及分子动力学模拟研究，结果显示二者结合亲和力较强，表明该复合物稳定性良好，该候选多表位疫苗有望成为疫苗研发的优质候选对象。