Identification and mutational analysis of continuous, immunodominant epitopes of the major oyster allergen Crag 1

• Published in: Clinical immunology (Orlando, Fla.) Vol. 201; pp. 20 - 29
• Main Authors: Fang, Lei, Li, Guoming, Zhang, Jiangtao, Gu, Ruizeng, Cai, Muyi, Lu, Jun
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2019
• Subjects: Adult; Allergens - genetics; Allergens - immunology; Amino Acid Sequence; Animals; Cra g 1; Epitope; Humans; IgE; Immunodominant Epitopes - genetics; Immunodominant Epitopes - immunology; Immunoglobulin E - blood; Immunoglobulin E - immunology; Mutation; Ostreidae - genetics; Ostreidae - immunology; Oyster; Shellfish Hypersensitivity; Tropomyosin; Tropomyosin - genetics; Tropomyosin - immunology; Cra g 1; Mutation; Epitope; Oyster; Tropomyosin; IgE
• ISSN: 1521-6616; 1521-7035
• DOI: 10.1016/j.clim.2019.02.008

Shellfish, including oysters, often cause allergic reactions in children and adults. Oysters are inevitably consumed because of its delicacy and nutritional benefit, leading to frequent occurrence of severe clinical symptoms observed in patients with oyster hypersensitivity. We aimed to identify the immunodominant epitopes of oyster tropomyosin and crucial amino acids for IgE binding, which will help us to further understand the immunochemical characteristics of Cra g 1. The potential epitopes were predicted by immunoinformatics tools and the resultant immunodominant epitopes were identified by inhibition ELISA with pooled sera and individual serum from oyster allergic patients. Surprisingly, homologous substitution of multiple amino acids led to obviously decrease affinity of IgE antibodies, but this manner did not abrogate binding completely. Five major linear epitopes were evenly distributed on the surface of homology-based Cra g 1 model and hydrophilic residues appeared to be the most important for IgE binding. These results not only offer a better understanding of the molecular mechanism of interaction between Cra g 1 and oyster-specific IgE but also have significance in clinical diagnosis and immunotherapy. •Five immunodominant epitopes of Cra g 1 were identified by immunoinformatics tools and inhibition ELISA, homologous substitution of multiple amino acids led to obviously decrease affinity of IgE antibodies.•Surprisingly, homologous substitution of multiple amino acids led to obviously decrease affinity of IgE antibodies, but this manner did not abrogate binding completely.•Five major linear epitopes were even distributed on the surface of homology-based Cra g 1 model and hydrophilic residues appeared to be the most important for IgE binding.