PDCD1 and hepatocellular carcinoma: Murine HCC cell lines (H22, Hepa1-6) and non-malignant controls (NCTC-1496 hepatocytes, VERO kidney epithelial cells) were infected with WT-VV, vv-MCZ, vv-PD-1, vv-FilC, or vv-PD-1/FilC at MOIs of 0.01, 0.1, 1, and 10 pfu/cell.