Couto Joana, Seixas Gonçalo, Stutzer Christian, Olivier Nicholas A, Maritz-Olivier Christine, Antunes Sandra, Domingos Ana
Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira, 100, 1349-008 Lisboa, Portugal.
Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (GHTM-IHMT-UNL), Rua da Junqueira, 100, 1349-008 Lisboa, Portugal.
Biomedicines. 2021 Mar 31;9(4):363. doi: 10.3390/biomedicines9040363.
In the wake of the 'omics' explosion of data, reverse vaccinology approaches are being applied more readily as an alternative for the discovery of candidates for next generation diagnostics and vaccines. Promising protective antigens for the control of ticks and tick-borne diseases can be discovered by mining available omics data for immunogenic epitopes. The present study aims to explore the previously obtained sialotranscriptome during both feeding and infection, to select antigenic targets that are either membrane-associated or a secreted protein, as well as unique to the ectoparasite and not present in the mammalian host. Further, they should be capable of stimulating T and B cells for a potential robust immune response, and be non-allergenic or toxic to the host. From the transcriptome, 5706 and 3025 proteins were identified as belonging to the surfaceome and secretome, respectively. Following a reverse genetics immunoinformatics pipeline, nine preferred candidates, consisting of one transmembrane-related and eight secreted proteins, were identified. These candidates showed a higher predicted antigenicity than the Bm86 antigen, with no homology to mammalian hosts and exposed regions. Only four were functionally annotated and selected for further in silico analysis, which examined their protein structure, surface accessibility, flexibility, hydrophobicity, and putative linear B and T-cell epitopes. Regions with overlapping coincident epitopes groups (CEGs) were evaluated to select peptides that were further analyzed for their physicochemical characteristics, potential allergenicity, toxicity, solubility, and potential propensity for crystallization. Following these procedures, a set of three peptides from the three proteins were selected. In silico results indicate that the designed epitopes could stimulate a protective and long-lasting immune response against those tick proteins, reflecting its potential as anti-tick vaccines. The immunogenicity of these peptides was evaluated in a pilot immunization study followed by tick feeding to evaluate its impact on tick behavior and pathogen transmission. Combining in silico methods with in vivo immunogenicity evaluation enabled the screening of vaccine candidates prior to expensive infestation studies on the definitive ovine host animals.
随着“组学”数据的激增，反向疫苗学方法作为发现下一代诊断和疫苗候选物的替代方法正得到更广泛的应用。通过挖掘现有的组学数据寻找免疫原性表位，可以发现有望用于控制蜱虫及蜱传疾病的保护性抗原。本研究旨在探索先前在蜱虫取食和感染过程中获得的唾液转录组，以选择与膜相关或分泌型的抗原靶点，这些靶点是外寄生虫所特有的，不存在于哺乳动物宿主中。此外，它们应能够刺激T细胞和B细胞产生潜在的强大免疫反应，并且对宿主无致敏性或毒性。从转录组中，分别鉴定出5706种和3025种蛋白质属于表面蛋白质组和分泌蛋白质组。按照反向遗传学免疫信息学流程，鉴定出9个优选候选物，包括1个跨膜相关蛋白和8个分泌蛋白。这些候选物显示出比Bm86抗原更高的预测抗原性，与哺乳动物宿主和暴露区域无同源性。仅对其中4个进行了功能注释并选择用于进一步的计算机分析，该分析检查了它们的蛋白质结构、表面可及性、柔韧性、疏水性以及推定的线性B细胞和T细胞表位。对具有重叠一致表位组（CEG）的区域进行评估，以选择肽段，并进一步分析其理化特性、潜在致敏性、毒性、溶解性以及结晶的潜在倾向。按照这些程序，从这三种蛋白质中选择了一组三个肽段。计算机模拟结果表明，设计的表位可以刺激针对那些蜱虫蛋白产生保护性和持久的免疫反应，反映出其作为抗蜱疫苗的潜力。在一项初步免疫研究中评估了这些肽段的免疫原性，随后进行蜱虫取食以评估其对蜱虫行为和病原体传播的影响。将计算机模拟方法与体内免疫原性评估相结合，能够在对最终的绵羊宿主动物进行昂贵的侵染研究之前筛选疫苗候选物。
