A study to evaluate immune restoration following removal of viral antigen in non-cirrhotic hepatitis C virus (HCV) genotype (GT) 1a treatment-naïve and pegylated-interferon (pegIFN)/ribavirin (RBV) treatment-experienced adults receiving treatment with ombitasvir/paritaprevir/ritonavir and dasabuvir coadministered with ribavirin (RBV) for 12 weeks.

A study to evaluate the role of ombitasvir/paritaprevir/ritonavir and dasabuvir coadministered with RBV treatment leading to sustained virologic response 12 weeks post-dosing (SVR12) on the changes from baseline in IFN-stimulated gene (ISG) expression in peripheral blood mononucleated cells (PBMCs) in HCV GT 1a-infected adult participants.

Inclusion Criteria:

1. Screening laboratory result indicating hepatitis C viral (HCV) genotype (GT) 1a infection.
2. Chronic HCV infection.
3. Participants must be non-cirrhotic.
4. Participants must be treatment-naïve or have documentation that they were adherent to prior pegIFN/RBV combination therapy and meet the criteria of prior pegylated-interferon (pegIFN)/ribavirin (RBV) treatment failure.
5. Participants must meet specific human leukocyte antigen (HLA) allele requirements.

Exclusion Criteria:

1. Women who are pregnant or breastfeeding.
2. Positive test result for hepatitis B surface antigen (HBsAg) or anti-human immunodeficiency virus antibody (HIV Ab) positive immunoassay.
3. Clinically significant abnormalities or co-morbidities, other than HCV infection, that make the subject unsuitable for this study or treatment.
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 pegIFN or RBV (including previous exposure to paritaprevir, ombitasvir, or dasabuvir), or receipt of any investigational product within 6 weeks prior to study drug administration.
5. History of solid organ transplant.
6. Screening laboratory analysis that shows abnormal results.