Genetic attachment of undecane peptides to ovomucoid third domain can suppress the production of specific IgG and IgE antibodies

Abstract

Rationale Egg white is the most common source of food allergy in children and ovomucoid Gad d1 is the dominant allergens in eggs. Previously, we mapped an entire sequential IgE epitope on ovomucoid. Molecular approaches are powerful tool to investigate the structure-function relationships of food allergens. In this study, we inducted genetic modification of ovomucoid third domain (DIII) and investigated its effect on specific antibody production. Methods An undecane peptide (Gly-Ser-Pro-Gly-Ile-Pro-Gly-Ser-Thr-Gly-Met) was genetically attached to the N-terminus of DIII to investigate structural characteristics of linear IgE and IgG (B cell) epitopes in DIII with respect to modulation of the immune response towards antigenicity and allergenicity. Balb/c mice were sensitized with native DIII, wild type recombinant DIII and recombinant modified DIII containing the extra amino acid stretch. The immune responses to the antigens were compared using ELISA. Results and conclusions Specific IgE and IgG levels were suppressed when the modified DIII was used as antigen. This was further confirmed by synthesizing immunodominant IgE and IgG epitopes of DIII on cellulose acetate membrane (SPOTs) and probing them with antibodies raised against DIII antigens. Anti-recombinant wild type DIII anti-serum showed strong binding activities to immunodominant IgE and IgG epitopes, while anti-modified DIII serum did not show any significant binding to the IgE and IgG epitopes. Thus, it is clearly demonstrated that the amino acid stretch in DIII is masking the immune reactive epitope. Genetically attachment of peptides into DIII was found to be effective in reducing the production of specific IgE and IgG antibodies in mice.