This open-label study will evaluate the safety and efficacy of co-formulated ombitasvir/paritaprevir/ritonavir and dasabuvir co-administered with sofosbuvir with or without ribavirin administered for either 4 or 6 weeks in treatment naive adults with chronic HCV-genotype 1 infection without cirrhosis

Inclusion Criteria:

1. Male or female at least 18 years of age at time of screening
2. Chronic Hepatitis C virus (HCV) infection prior to study enrollment
3. Screening laboratory results from the central clinical laboratory indicating HCV genotype 1 infection only
4. Absence of cirrhosis and advanced bridging fibrosis

Exclusion Criteria:

1. Positive test result for hepatitis B surface antigen (HbsAg) or human immunodeficiency virus (HIV) positive immunoassay
2. Clinically significant abnormalities or co-morbidities, other than HCV infection, that make the subject an unsuitable candidate for this study or treatment with Ribavirin (RBV) in the opinion of the investigator
3. Any current or past clinical evidence of cirrhosis such as ascites or esophageal varices, or prior biopsy showing cirrhosis or advanced bridging fibrosis, e.g., a Metavir score > 2 or an Ishak score > 3
4. Use of medications contraindicated for ombitasvir/paritaprevir/ritonavir, dasabuvir, sofosbuvir, or ribavirin (RBV; for those that receive RBV), within 2 weeks or 10 half-lives whichever is longer, prior to study drug administration
5. Current enrolment in another clinical study, previous enrolment in this study, or previous use of any investigational or commercially available anti-HCV agents