Study to Investigate the Efficacy and Safety of GS-7977 Plus Ribavirin for 12 Weeks in Chronic Genotype 2 and 3 Hepatitis C Virus (HCV) and Human Immunodeficiency Virus (HIV) Co-Infected Subjects

Inclusion Criteria:

Subjects must meet all of the following inclusion criteria to be eligible for
participation in this study.

1. Willing and able to provide written informed consent

2. Male or female, age ≥ 18 years with chronic HCV and HIV-1 infection

3. HCV RNA > 1 x 104 IU/mL at Screening

4. Infection with HCV genotype 2 or 3 as determined at Screening

5. HIV-1 infection confirmed with positive ELISA or Western blot at Screening

6. The subject's medical records must be sufficient to be categorized on IFN eligibility
or prior treatment history with PEG/RBV.

7. Confirmation of chronic HCV infection

8. Ability to determine presence/absence of cirrhosis.

9. HIV antiretroviral therapy (ARV) criteria of one of the following:

- ARV untreated with a CD4 T-cell count >500 cells/mm3

- On a stable, protocol-approved, ARV for >8 weeks prior to Screening with a CD4
T-cell count >200 cells/mm3 and a documented undetectable plasma HIV-1 RNA level
for ≥ 8 weeks preceding the Screening visit

10. Approved HIV antiretroviral medications based on drug interaction studies

11. Subject has not been treated with any investigational drug or device within 30 days
of the Screening visit

12. Females if confirmed that she is not pregnant or nursing of non-childbearing
potential or of childbearing potential but has a negative serum pregnancy test at
screening and agrees to use two highly effective methods of birth control from
screening through 6 months after the last dose of RBV

13. Male subjects who agree to consistently and correctly use a condom while their female
partner agrees to use birth control

14. Subject must be of generally good health as determined by the Investigator.

15. Liver imaging within 6 months of Baseline/Day 1 is required in cirrhotic patients
only, to exclude hepatocellular carcinoma (HCC)

Exclusion Criteria:

Subjects who meet any of the following exclusion criteria are not to be enrolled in this
study.

1. Non-genotype 2/3 or mixed genotype at Screening

2. Poor control with ARV regimen

3. Prior exposure to a direct-acting antiviral targeting the HCV NS5B polymerase

4. Chronic liver disease of a non-HCV etiology (e.g., hemochromatosis, Wilson's disease,
α1 antitrypsin deficiency, cholangitis)

5. A new AIDS-defining condition diagnosed within 30 days prior to screening

6. Active, serious infection (other than HIV or HCV) requiring parenteral antibiotics,
antivirals or antifungals within 30 days prior to Baseline

7. Infection with hepatitis B virus (HBV)

8. Contraindication to RBV therapy

9. Chronic use of systemically administered immunosuppressive agents (e.g., prednisone
equivalent > 10 mg/day)

10. History of solid organ transplantation or malignancy diagnosed or treated within 5
years

11. Current or prior history of clinical hepatic decompensation or other significant
gastrointestinal disorder