The use of a Programmed Death (PD-1) antagonist and a viral antigen for treating a mammalian subject having a chronic hepatitis C viral infection. The antagonist can be an anti-PD1 antibody, an anti-Programmed Death Ligand 1 (PD-L1) or an anti-PD-L2 antibody; a siRNA or antisense RNA directed to PD-1, PD-L1 or PD-L2; or a dominant negative PD-1, PD-L1 or PD-L2 protein.