Safety and Efficacy of the Therapeutic Vaccine GI-5005 Combined With Pegylated Interferon Plus Ribavirin Standard of Care Therapy Versus Standard of Care Alone in Patients With Genotype 1 Chronic Hepatitis C Infection

Inclusion Criteria: * Chronic hepatitis C infection with genotype 1 based on serum positivity for HCV RNA or a positive test for serum anti-HCV antibody for at least 6 months; * One of the following response criteria based on response to prior combination therapy with pegylated or non-pegylated interferon plus ribavirin: Non-Responders * Poor responders - a subset of non-responders who achieved \> 1 log10 but \< 2 log10 reduction in HCV RNA after a minimum of 12 weeks of prior interferon based therapy. * Partial responders - a subset of non-responders who achieve at least a 2 log10 reduction in HCV RNA by 12 weeks, but do not achieve an end of treatment response (ETR defined as HCV RNA negativity by PCR assay at the end of a minimum of 6 months of therapy). Naive * Patients who are treatment naïve and have refused IFN therapy for reasons other than contraindication. * Signed, written, informed consent from the patient or legal representative before any study-specific procedures are performed; * Liver biopsy within 3 years of the screening visit, documenting extent of liver disease consistent with chronic hepatitis C with evidence of inflammation and/or fibrosis. Liver biopsy within 1 year for subjects consenting to paired biopsy testing. Eight unstained liver biopsy slides are required for the baseline sample and post-treatment sample for use in central blinded evaluation for paired biopsy testing; * Age ≥ 18 years; * Negative scratch test (immediate hypersensitivity, IgE mediated) to S. cerevisiae. Exclusion Criteria: * History of decompensated liver disease, including but not restricted to, portal hypertension as manifested by a known history of gastroesophageal varices, variceal bleeding, ascites or encephalopathy, histopathologic or clinical evidence of cirrhosis, hepatocellular carcinoma, or renal impairment consistent with hepatorenal syndrome; * History of significant non-HCV chronic liver disease, i.e. alcoholic hepatitis, autoimmune hepatitis; * Null response to prior IFN plus ribavirin therapy, defined as patients that have received at least 12 weeks of interferon-based treatment with \< 1 log10 reduction in viral load; * Subjects treated with more than 1 complete hepatitis C regimen (subjects with a history of 1 complete prior regimen and a second incomplete prior regimen may be eligible upon discussion with and approval of the medical monitor); * Subjects that required a dose reduction of \>25% of the planned exposure of IFN or \>50% of their planned ribavirin exposure during their previous interferon/ribavirin treatment; * Subjects that required growth factors during their previous interferon/ribavirin treatment; * Subjects that received small molecule inhibitor therapy combined with an interferon based regimen. (subjects that received small molecule inhibitor monotherapy can be included); * Treatment for HCV infection within 28 days before screening; * Chronic hepatitis B infection or positive hepatitis B surface antigen (HBsAg) at screening; * Body weight \>275 pounds; * Known history of HIV infection or positive HIV antibody test at screening; * History of Crohn's disease or ulcerative colitis; * Concurrent therapy with herbal supplements taken specifically for the treatment of HCV (i.e. milk thistle). Wash-out of HCV related herbals for 28 days prior to Day 1. Consult sponsor before excluding potential subjects; * Alcohol and/or IV drug abuse within the past year;