Identification and Cross-reactivity Analysis of Sarcoplasmic-Calcium-Binding Protein: A Novel Allergen in <i>Crassostrea angulata</i>

Abstract

Oysters are an important shellfish group known to cause food allergy; however, knowledge of their sensitization components and cross-reactivity is limited. This study aimed to identify a novel allergen in <i>Crassostrea angulata</i> and investigate its cross-reactivity. To this end, a 20 kDa protein was purified from oyster and confirmed to be a sarcoplasmic-calcium-binding protein (SCP) by LC-MS/MS. A 537 bp open reading frame was obtained from oyster SCP total RNA, which encoded 179 amino acids, and was expressed in <i>Escherichia coli</i>. According to the circular dichroism results, digestion assay, and inhibition ELISA, the recombinant SCP (rSCP) exhibited similar physicochemical properties and IgG-binding activity to native SCP. rSCP displayed stronger IgE-binding activity by immunological method. Moreover, a different intensity of cross-reactivity and sequence homology were demonstrated between shellfish species. Collectively, these findings provide novel insight into shellfish allergens, which can be used to aid in the <i>in vitro</i> diagnosis of oyster-sensitized patients.