Identification of cross-reactive B-cell epitopes between Gly m 5.0101 [Glycine max] and α-casein [Bos Taurus] by epitope mapping - mass spectrometry

BRONSOMS SILVIA; PETRUCCELLI SILVANA; FERRER-NAVARRO MARIO; CURCIARELLO RENATA; TREJO SEBASTIAN; CANDREVA ANGELA; QUIROGA ALEJANDRA; DOCENA GUILLERMO H.

Mar del Plata

Congreso; Reunion anual de la Sociedad Argentina de Fisiología SAFIS 2016; 2016

SAI

Cow's milk proteins are one of the most common causes of food allergy and intolerance in a restricted proportion of IgE-mediated milk allergic patients treated with soy formulae, due to the cross-allergenicity previously described. We aimed to characterize cross-reactive epitopes between prevalent soy and milk allergens using mass spectrometry tools. A bovine casein-specific monoclonal antibody (1D5 mAb), purified milk caseins (Bos d 8) and the recombinant soy allergen Gly m 5.0101 (rGlym5) were employed to identify linear epitopes by MALDI-TOF MS. The 1D5 mAb was immobilized onto magnetic beads and incubated with the peptide mixture previously obtained by enzymatic digestion of both allergens. The MALDI-TOF MS analysis was performed to compare bound and unbound peptide profiles. Finally, mapped peptides were sequenced de novo by MALDI-TOF to identify dominant epitopes.We showed that casein-specific 1D5 mAb recognized 4 peptides on αS1-casein and 3 cross-reactive epitopes in rGlym5 of mass: 2260.2 Da (residues 125to142); 1993.2 Da (residues 367to385) and 1864.0 Da (residues 527to543).The alignment of the sequences of these cross-reactivity peptides and peptides of αS1-casein, using the study of occurrence frequency analysis of this epitopes residues (by WebLogo), enables us to identify 4 critical residues charged and neutral (polar and non-polar ) for 1D5 mAb binding. In conclusion, this method identified common sequential B epitopes and critical aminoacidic between allergens with no phylogenetic relationship. These findings may be relevant for potential immunotherapies for patients and led us to understand the clinical intolerance of milk allergic patients that are exposed to soy formula as dairy substitute during treatment.