On the other hand, CLDN1, OCLN, SR-BI or CD81 knockdown in Huh7.5.1 cells potently inhibited the infection by HCVpp-JFH-1 (Fig. 4d,e), confirming the previous report describing essential roles of four co-receptors CLDN1, OCLN, CD81 and SR-BI for virus entry into hepatocytes12, 13, 16, 57. This evidence concerns the gene CD81 and infection.