HCV-specific CD8+ T cells had upregulated PD-1 expression during the acute stage of hepatitis C, but gradually expressed more CD127 in patients with resolving self-limited hepatitis C than in acute hepatitis B. In contrast, in patients with chronically evolving hepatitis C, CD127 expression continued to be negative with persistent PD-1 expression [114]. Here, PDCD1 is linked to hepatitis B virus infection.