In line with these inconsistent hypotheses, the only clinical trial with anti-PD-1 antibody for non-cancer patients with viral hepatitis showed that even though some patients have persistent suppression of HCV replication, only 5 of 42 patients (12%) met the primary endpoint of a ≥ 0.5 log reduction in HCV RNA [25]. Here, PDCD1 is linked to animal viral hepatitis.