苹果过敏原Mal d4蛋白抗原表位预测及交叉反应分析

目的:预测苹果过敏原Mal d 4蛋白B细胞和T细胞抗原表位,探讨Mal d 4蛋白与其同源蛋白之间的交叉反应性.方法:以苹果过敏原Mal d 4蛋白的氨基酸序列为基础,采用生物信息软件HNN预测二级结构;运用DNAStar和Bcepred软件预测其B细胞抗原表位,用NetMHCⅡ、NetMHCⅡpan、Syfpeithi及Propred软件综合预测T细胞抗原表位;采用Clustal X1.83、Swiss-Model软件比对同源序列和模拟空间构象.结果:该蛋白二级结构以无规则卷曲为主.B/T细胞共同抗原表位的区域为53～61、85～93.苹果Mal d 4蛋白与桃、芒果、甜樱桃、草莓中的前纤维蛋白氨基酸序列同源性达88%以上,空间构象相似.结论:苹果过敏原Mal d 4蛋白与桃、芒果、甜樱桃和草莓的前纤维蛋白之间可能存在交叉反应,其优势抗原表位区域可能为53～61、85～93,是后续过敏原改造的重点,为继续深入开展苹果过敏原基础性研究提供理论依据.

Prediction of antigenic epitopes and cross-reactivity of apple allergen Mal d 4

Objective: To predict B/T cell antigenic epitopes of apple allergen Mal d 4 and analyse the cross-reactivity between apple allergen Mal d 4 and other homologous proteins.Methods: Secondary structure of apple Mal d 4 protein was predicted by HNN software,B cells antigenic epitopes were predicted using the bioinformatics tools DNAStar and Bcepred,T cells antigenic epitopes were predicted through NetMHCⅡ,NetMHCⅡpan,Propred and Syfpeithi.The homologous sequence alignment and conformation were analysed by Clustal X1.83 and Swiss-Model software.Results: Secondary structure of apple allergen Mal d 4 was mainly composed by random coil.Combined the prediction results of B / T cells antigenic epitopes,the possible epitope regions of apple allergen Mal d 4 were 53-61 and 85-93.The amino acid sequence homology between apple Mal d 4 protein and profilins of peach,mangifera,sweet cherry,strawberry were above 88%.Similar conformation provided a basis for the existence of cross-reactivity.Conclusion: Apple allergen Mal d 4 may cross-react with profilins of peach,mangifera,sweet cherry,strawberry.The dominant epitopes of Mal d 4 are 53-61 and 85-93,which may be the key sites for follow-up modification.This research also provides a theoretical basis for further study on apple allergen.