Based on the recently highlighted role of PD-1 contributing to the dysfunction of T-cells in chronic viral infections, we also determined whether HIV and HCV-specific intra-hepatic T-cells differ in the degree of PD-1 expression. In an HCV/HIV coinfected liver, we found that 100% of intra-hepatic HCV-specific CD8 + T-cells were PD-1 positive, compared to 48.8% of those cells that were HIV-specific (Figure 5d ).