Allergy and Immunology section, CSIR-Institute of Genomics and Integrative Biology, New Delhi-110007, India.
Department of Biochemistry, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi-110062, India.
Curr Protein Pept Sci. 2022;23(7):475-494. doi: 10.2174/1389203723666220804124927.
In-silico mapping of epitopes by immune-informatics has simplified the efforts towards understanding antigen-antibody interactions. The knowledge of allergen epitopes may help in advancing the diagnosis and therapy of allergic diseases.
This study was intended to identify B and T cell epitopes of cysteine protease allergen of Phaseolus vulgaris.
Modeller 9v20 software was used for the generation of three-dimensional model of cysteine protease and quality assessment was performed using SAVES webserver and other in silico software. Linear and conformational B and T cell epitopes were predicted via immuno-informatics based computational servers. Epitopes were synthesized and their immunoreactivity was analyzed using specific IgE ELISA with food allergy positive patient's sera. Cellular immune response of peptides was determined through basophil activation assay. Consurf and SDAP (property distance) were used to examine the evolutionary conservancy and potential cross-reactivity of predicted epitopes. MSA based positional conservancy between HDM allergen epitopes and predicted peptides was also established using IEDB epitope database. Finally, population coverage for each promiscuous T cell epitope was predicted using IEDB population coverage analysis tool.
Cysteine protease structure was derived by homology modeling and combination of bioinformatic tools predicted three B- and three T-cell peptides by consensus method and validated computationally. ELISA with kidney bean sensitive patient's sera showed higher IgE binding of B-cell peptides as compared to T-cell or control peptides. Epitope conservancy revealed B-cell epitopes being upto 95% conserved in comparison to variable T-cell epitopes (upto 69%). B-cell peptides were crossreactive with homologous allergens based on PD values. Structural comparison of cysteine protease with Der p 1 and Der f 1 showed similar epitopic regions, validating the prediction accuracy of epitopes. Promiscuous T-cell epitopes binding to broad-spectrum class-II MHC alleles demonstrated the distribution of T-cell peptides world-wide (30-98%) and in Asian population (99%).
The current approach can be applied for identification of epitopes. Analysis of crossreactive and widely-distributed specific epitopes of allergen and knowledge about their interactive surfaces will help in understanding of food allergy and related immune responses.
免疫信息学通过计算预测表位，简化了对抗原-抗体相互作用的理解。过敏原表位的知识可能有助于推进过敏性疾病的诊断和治疗。
本研究旨在鉴定菜豆半胱氨酸蛋白酶过敏原的 B 细胞和 T 细胞表位。
使用 Modeller 9v20 软件生成半胱氨酸蛋白酶的三维模型，并使用 SAVES 网络服务器和其他计算软件进行质量评估。通过基于免疫信息学的计算服务器预测线性和构象 B 细胞和 T 细胞表位。通过使用食物过敏阳性患者的血清进行特异性 IgE ELISA 分析，合成表位并检测其免疫反应性。通过嗜碱性粒细胞激活测定确定肽的细胞免疫反应。使用 Consurf 和 SDAP（属性距离）检查预测表位的进化保守性和潜在交叉反应性。还使用 IEDB 表位数据库在基于多重序列比对（MSA）的位置保守性之间建立 HDM 过敏原表位和预测肽之间的关系。最后，使用 IEDB 人群覆盖分析工具预测每个混合 T 细胞表位的人群覆盖率。
通过同源建模获得半胱氨酸蛋白酶结构，并结合生物信息学工具通过共识方法预测了三个 B 细胞和三个 T 细胞肽，并通过计算进行了验证。使用菜豆敏感患者的血清进行 ELISA 显示，B 细胞肽的 IgE 结合比 T 细胞肽或对照肽更高。表位保守性显示 B 细胞表位与可变 T 细胞表位（高达 69%）相比高达 95%保守。基于 PD 值，B 细胞肽与同源过敏原发生交叉反应。半胱氨酸蛋白酶与 Der p 1 和 Der f 1 的结构比较显示出相似的表位区域，验证了表位的预测准确性。与广谱 II 类 MHC 等位基因结合的混合 T 细胞表位表明 T 细胞肽在全球（30-98%）和亚洲人群（99%）中的分布。
目前的方法可用于鉴定表位。分析过敏原的交叉反应和广泛分布的特异性表位及其相互作用表面的知识将有助于理解食物过敏和相关免疫反应。
