Identification of B cell epitopes of Per a 5 allergen using bioinformatic approach

• Published in: Immunobiology (1979) Vol. 226; no. 6; p. 152146
• Main Authors: Sharma, Swati, Vashisht, Srishti, Gaur, S.N., Lavasa, Shakuntala, Arora, Naveen
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier GmbH 01.11.2021
• Subjects: Algorithms; Allergens - chemistry; Allergens - immunology; Amino Acid Substitution; Animals; B cell epitopes; Binding Sites; Computational Biology - methods; Conserved Sequence; Cross Reactions - immunology; Epitope conservation; Epitope Mapping - methods; Epitopes, B-Lymphocyte - chemistry; Epitopes, B-Lymphocyte - immunology; Evolution, Molecular; Glutathione Transferase - chemistry; Glutathione Transferase - immunology; GST allergens; Humans; Hydrophobic and Hydrophilic Interactions; Immunoglobulin E - chemistry; Immunoglobulin E - immunology; Insect Proteins - chemistry; Insect Proteins - immunology; Models, Molecular; PD values; Peptides - chemistry; Peptides - immunology; Protein Binding; Protein Conformation; Structure-Activity Relationship; B cell epitopes; PD values; Epitope conservation; GST allergens
• ISSN: 0171-2985; 1878-3279
• DOI: 10.1016/j.imbio.2021.152146

•Per a 5 allergen structure was homology modelled and its B cell epitopes were identified by in silico tools.•IgE binding analysis reveals epitope BC-P3 as a major IgE binding epitope followed by BC-P1 and BC-P2.•Computational analysis indicates epitope similarity with allergenic proteins belonging to insect, fungal and helminth allergens and several fruits and nut allergen sources.•BC-P2 emerged as potentially cross reactive epitopes with cockroach, fungal and mite allergens, while BC-P5 was recognized by fungal and mite hypersensitive sera samples. Immune epitopes of allergens are pivotal for development of novel diagnostic and therapeutic modalities. Present study aims to identify antigenic determinants of Per a 5, a clinically relevant cross reactive cockroach allergen. The three dimensional structure of Per a 5 was modelled using Modeller 9v11 software. A combination of sequence and structure based computational tools were employed for predicting B cell epitopes. Epitopes were synthesized and immunoreactivity was assessed by ELISA using cockroach hypersensitive patient’s sera. Cross-reactivity potential of predicted epitopes was assessed with SDAP and ConSurf and validated by IgE ELISA with fungal and mite hypersensitive patient’s sera. Per a 5 structure exhibited good quality factor in ERRAT and high stereochemical stability. In silico analysis revealed six B cell epitopes (BC-P1 to P6). BC-P3 demonstrated significant IgE binding followed by BC-P2 and BC-P1 with cockroach hypersensitive patient’s sera. Per a 5 epitopes demonstrate considerable similarity with broad spectrum of allergens from fungal, mites, helminths, fruits and nuts. Analysis of PD values indicate BC-P4 to be well conserved among dust mite and helminth GSTs (8.89, 10.63 and 10.69 with D. pteronyssinus, W. bancrofti and F. hepatica respectively). ConSurf analysis of Per a 5 revealed specific enrichment of evolutionarily similar amino acid residues in BC-P2 (with fungal and mite GSTs) and BC-P4 (with mite and helminth GSTs). Further, IgE binding analysis of epitopes demonstrate BC-P2, BC-P3 and BC-P5 as high IgE binders in fungal hypersensitive sera while BC-P1, BC-P2, BC-P4 and BC-P5 demonstrated significant IgE binding with mite hypersensitive sera. Among the predicted epitopes, BC-P3 demonstrates maximal IgE binding ability. Computational analysis suggests strong evolutionary conservation and cross reactive potential of BC-P4 with allergens in dust mite and helminths. ELISA highlights predictive potential of analysing evolutionarily conserved residues for uncovering potentially cross reactive antigenic determinants. Immune epitopes of Per a 5 were identified for aiding molecular diagnosis and potential cross reactivity.