This is a Phase 2b, Randomized, Double-Blind, Placebo-Controlled Trial Evaluating Response Guided Therapy with GS-5885 Alone or in Combination with GS-9451 with Peginterferon Alfa 2a and Ribavirin in Treatment Naïve Subjects with Chronic Genotype 1 Hepatitis C Virus Infection.

Inclusion Criteria:

• Males and females 18-70 years of age
• Chronic HCV infection
• Subjects must have liver biopsy results (≤ 2 years prior to Screening) indicating the absence of cirrhosis.
• Monoinfection with HCV genotype 1
• HCV RNA > 10^4 IU/mL at Screening
• HCV treatment naïve
• Candidate for PEG/RBV therapy
• Body mass index (BMI) 18-36 kg/m2, inclusive
• Agree to use two forms of highly effective contraception methods for the duration of the study and for 7 months after the last dose of study medication. Females of childbearing potential must have negative pregnancy test at Screening and Baseline.

Exclusion Criteria:

• Pregnant female or male with pregnant female partner
• Exceed defined thresholds for leukopenia, neutropenia, anemia, thrombocytopenia, thyroid stimulating hormone (TSH)
• Diagnosis of autoimmune disease, decompensated liver disease, poorly controlled diabetes mellitus, significant psychiatric illness, severe chronic obstructive pulmonary disease (COPD), HIV, hepatitis B virus (HBV), hepatocellular carcinoma or other malignancy (with exception of certain resolved skin cancers), hemoglobinopathy, retinal disease, or are immunosuppressed.
• Subjects with current use of amphetamines, cocaine, opiates (e.g., morphine, heroin), or ongoing alcohol abuse are excluded. Patients on stable methadone or buprenorphine maintenance treatment for at least 6 months prior to Screening may be included into the study.