ORF8 is an asymmetric covalent AB homodimer of 121 amino acid monomers (15 first residues of signal peptide per monomer). The core of each monomer consists of two antiparallel β-sheets . Crystallographically, two different possible dimer interfaces have been proposed, the demonstrated interface stabilized by a C- C disulphide covalent bond and the hypothetical non-covalently stabilized by YIDI-motif hydrophobic interactions .