Patient description: A 53-year-old man presents with chronic HCV infection for the past 2 years. His past medical history is only significant for inguinal hernia surgery when he was 20 years old. He is on IFN (100 mg/week) plus RBV (400 mg/day) combination therapy for the past 9 months. Direct antiviral drugs were added to his treatment 6 months ago. His medical record shows previous positive HCV RNA tests as well as positive enzyme immunoassay for anti-HCV-antibodies. The recent biopsy was negative for hepatocellular carcinoma and was only remarkable for chronic inflammation compatible with a chronic viral hepatitis. There is no evidence of alcoholic liver disease, bleeding from esophageal varices, hemochromatosis, autoimmune hepatitis or metabolic liver disease. He is an alert male with no acute distress. His BP: 130/75, HR: 90/min and BMI: 27. His abdomen is soft with no ascites or tenderness. The lower extremities are normal with no edema.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Hepatitis C HIV Eighteen years of age or older at screening. 2. HCV treatment-naive, as defined as no prior exposure to any IFN, RBV, or other approved or experimental HCV-specific direct-acting antiviral agent. 3. Participants must be willing to practice either: 1. Abstinence from sexual intercourse or 2. At least 2 forms of contraception including one barrier method from 2 weeks prior to Day 0 through 30 days after the last dose is received. i. Female partners of male study subjects may rely upon hormonal contraception as one of the 2 methods; however female study subjects may not. 4. Chronic hepatitis C infection defined as one of the following: 1. Positive for anti-HCV antibody, HCV RNA, or an HCV genotype at least 6 months before screening, and positive for HCV RNA and anti-HCV antibody at the time of screening or 2. Positive for anti-HCV antibody and HCV RNA at the time of screening with a liver biopsy consistent with chronic HCV infection (or a liver biopsy performed before enrollment with evidence of chronic hepatitis C disease, such as the presence of fibrosis). 5. HIV treatment status: 1. Documented HIV infection, ARV untreated for > 8 weeks preceding dosing and having either: 1. a CD4 T-cell count greater than or equal to 500 cells/mm3 within 8 weeks of Day 0 or 2. an HIV viral load less than 500 copies/mL with a stable CD4 count for at least 3 months. 2. Documented HIV infection on a stable, protocol-approved, ARV regimen for greater than or equal to 8 weeks prior to dosing and is expected to continue the current ARV regimen through the end of study with all of the following: 1. a CD4 T-cell count > 100 cells/mm3 2. a documented plasma HIV-1 RNA level less than the level of detection for at least 8 weeks preceding dosing. If the lower limit of detection of the local HIV-1 RNA assay is < 50 copies/mL (e.g.,< 20 copies/mL), the Screening plasma HIV-1 RNA level cannot exceed 50 copies/mL. 3. HIV ARV agents including only combination regimens consisting of medications from the following list: tenofovir (TDF), emtricitabine (FTC), efavirenz, raltegravir, and rilpivirine administered according to their manufacturer s prescribing information. (reference Section 10.3 for additional information) 6. Documentation of hepatitis C genotype 1a, 1b or mixed 1a/1b 7. Absence of cirrhosis, defined as one of the following: 1. A liver biopsy performed within 36 calendar months of screening showing absence of cirrhosis. 2. FibroTest score of < 0.48 AND APRI of < 1 performed during the 8 weeks preceding dosing (In the absence of a definitive diagnosis of presence or absence of cirrhosis by the above a liver biopsy is required). 8. Able to effectively communicate with the Investigator and other center personnel. 9. Willing to give written informed consent and comply with the study restrictions and requirements. 10. If opioid-dependent, subjects must be participating in a supervised treatment. 11. Participants must have a primary medical provider outside of OP8 and the NIH for medical management  Subjects who meet any of the following are not to be enrolled in this study: 1. Current or prior history of any of the following: 1. Clinically significant illness (other than HCV) or any other major medical disorder that may interfere with subject treatment, assessment or compliance with the protocol; subjects currently under evaluation for a potentially clinically-significant illness (other than HCV) are also excluded. 2. Gastrointestinal disorder or post-operative condition that could interfere with the absorption of the study drug. 3. Poor venous access interfering with required study blood collection. 4. Clinical hepatic decompensation (i.e., ascites, encephalopathy or variceal hemorrhage). 5. Solid organ transplantation. 6. Significant pulmonary disease, significant cardiac disease or porphyria. 7. Unstable psychiatric disease (Subjects with psychiatric illness that is well-controlled on a stable treatment regimen or currently not requiring medication may be included). 8. Any malignancy or its treatment that in the opinion of the PI may cause ongoing interference with host immunity; subjects under evaluation for malignancy are not eligible. 9. Significant drug allergy (such as anaphylaxis or hepatotoxicity). 10. Chronic liver disease of a non-HCV etiology (e.g., hemochromatosis, Wilson s disease, alfa-1 antitrypsin deficiency, cholangitis). 11. Patients with renal impairment or uncontrolled medical problems that could place them at high risk for developing renal impairment. 2. Positive test at screening for either HBsAg or quantifiable HBV DNA (completed only if necessary to rule out chronic HBV) 3. Current use of non-protocol approved ARVs. 4. A new AIDS-defining condition diagnosed within 30 days prior to screening or active, serious infection (other than HIV or HCV) requiring parenteral antibiotics, antivirals or antifungals within 30 days prior to Day 0. 5. Cirrhosis of the liver 6. Screening or baseline ECG with clinically significant ECG findings. 7. Abnormal hematological and biochemical parameters, including: 1. Neutrophil count < 750 cells/mm(3) 2. Hemoglobin < 9 g/dL. If Hgb is < 11g/dL in women or < 12 g/dL in men. Other causes of anemia should be excluded as medically indicated. 3. Platelet count less than or equal to 50,000 cells/mm(3) 4. Estimated GFR (calculated by the CKD-EP(I) equation) < 50 mL/min/per 1.73 m(2) if not on ARV or < 60 mL/min if on ARVs 5. ALT or AST greater than or equal to 10 times ULN 6. Serum lipase greater than or equal to 1.5 times ULN (at screening or during the screening period) 7. Direct bilirubin greater than or equal to 1.50 times ULN 8. Albumin less than or equal to 3.0 g/dL 9. INR greater than or equal to 1.5 times ULN unless subject has known hemophilia or is stable on an anticoagulant regimen affecting INR. 8. Donation or loss of more than 400 mL blood within 8 weeks prior to first dose administration. 9. Poorly controlled diabetes mellitus indicated by hemoglobin A1C > 10% at screening for known diabetics. 10. Known hypersensitivity to, GS-5885, GS-7977, or formulation excipients. 11. Pregnant/Breastfeeding women. 12. Co-enrollment in other clinical trials is restricted, and requires approval of the Investigator. Study staff should be notified of co-enrollment status. 13. Need for use of the following medications from 21 days prior to the start of study drugs through the end of treatment: 1. Hematologic stimulating agents (e.g. erythropoiesis-stimulating agents (ESAs); granulocyte colony stimulating factor (GCSF); thrombopoietin (TPO) mimetics) 2. Chronic systemic immunosuppressants including, but not limited to, corticosteroids (prednisone equivalent of > 10 mg/day for > 2 weeks), azathioprine, or monoclonal antibodies (e.g., infliximab) 3. Investigational agents or devices for any indication 4. Medications for disease conditions excluded from the protocol (e.g., active cancer, transplantation) are not listed under this Concomitant Medication section and are disallowed in the study. 5. Concomitant use of certain medications or herbal/natural supplements per PI discretion expected to result in pharmacokinetic interactions resulting in increases or decreases in exposure of study drug(s) as listed in Table of this protocol