A Study to Evaluate Treatment of Hepatitis C Virus Infection in Pediatric Subjects

1. Positive anti-hepatitis C virus antibody (HCV Ab) and HCV ribonucleic acid (RNA) ≥ 1000 IU/mL at the time of screening 2. HCV genotype 1 for enrollment into Part 1 of the study and genotype 1 or 4 for enrollment into Part 2 3. Parent or legal guardian with the willingness and ability to provide written informed consent and participant willing and able to give assent, as appropriate for age and country

1. Female participant who is pregnant, breastfeeding or is considering becoming pregnant 2. Use of known strong inducers and inhibitors (e.g., gemfibrozil) of cytochrome P450 2C8 (CYP2C8) in participants receiving dasabuvir, or strong or moderate inducers of CYP3A, within 2 weeks or 10 half-lives, whichever is longer, of the respective medication/supplement prior to study drug administration. 3. Positive test result for Hepatitis B surface antigen (HbsAg) or anti-human immunodeficiency virus antibody (HIV Ab) test 4. Current enrollment in another interventional clinical study, previous enrollment in this study, prior or current use of any investigational or commercially available anti-HCV agents other than interferons or ribavirin or receipt of any investigational product within 6 weeks prior to study drug administration