CD81 and infection: All cell lines were equally permissive for VSVGpp infection (8 × 105-9 × 105 RLU, data not shown) however, only Huh7, Hep3B, PLC and HepG2 cells stably expressing CD81 (HepG2-CD81, Additional file 1: Figure S1) were permissive for HCVpp infection (Figure 1A).