a, Schematic representation of the E2 protein with the CD81-binding loop highlighted in yellow and the asterisks highlighting regions associated with CD81 binding. b, Multiple sequence alignment of eE2 from representative strains (as labelled) of the seven genotypes. Conserved residues (cyan highlights) and CD81-binding loop residues (red font) are noted. Asterisks indicate residues ≤4Å from tamarin CD81 common to both chains C and G (red), chain G only (blue), and chain A only (green). Hypervariable region, antigenic site, and transmembrane are labelled HVR, AS and TM, respectively.