A multi-antigen DNA vaccine consisting of plasmids encoding the hepatitis C virus (HCV) nonstructural proteins 3 (NS3), 4A (NS4A), 4B (NS4B) and 5A (NS5A), with potential immunomodulating and cancer preventive activities. Administered via intramuscular injection followed by electroporation, cells transfected with the HCV DNA vaccine INO-8000 express the encoded HCV proteins, which may elicit a cytotoxic T-lymphocyte (CTL) response against HCV-infected liver cells expressing the NS3, NS4A, NS4B or NS5A proteins. This results in the eradication of HCV-infected cells. HCV, a small, enveloped, single-stranded RNA virus belonging to the Flaviviridae family, is associated with the development of hepatocellular carcinoma (HCC).