An Efficacy and Safety Study of MK-5172 + MK-8742 in the Treatment of Chronic Hepatitis C Virus Genotype 1, 4, or 6 Infection in Treatment-Naïve Participants Who Are on Opiate Substitution Therapy (MK-5172-062)

Inclusion Criteria:

- Documented chronic HCV genotype 1 (GT1), GT4, or GT6 infection with no evidence of
GT2 or GT3 or non-typeable genotypes and HCV ribonucleic acid (RNA) confirmed by
screening lab results prior to randomization

- On opiate substitution therapy (OST; methadone, levamethadone, buprenorphine,
naloxone, naltrexone) for at least 3 months prior to screening

- Treatment naïve to all HCV therapies

- Human Immunodeficiency Virus (HIV)-infected participants enrolled in this study must
meet following criteria:

- Documented HIV infection

- Naïve to treatment with any antiretroviral therapy (ART) OR on HIV ART for at least 8
weeks prior to study entry using a dual nucleoside reverse transcriptase inhibitor
(NRTI) backbone of tenofovir or abacavir and either emtricitabine or lamivudine PLUS
raltegravir (or dolutegravir or rilpivirine). Dose modifications or changes in ART
during the 4 weeks prior to study entry (Day 1) are not permitted

- Cluster of differentiation 4 (CD4+) T-cell count >200 cells/mm^3 if on ART or >500
cell/mm^3 if ART treatment naïve

- Undetectable plasma HIV-1 RNA at least 8 weeks prior to screening if on ART or
<50,000 copies/mL if ART treatment naïve

- Participants with HIV-1 infection and on ART must have at least one viable
antiretroviral regimen alternative beyond their current regimen in the event of HIV
virologic failure or the development of anti-retroviral drug resistance

- Females who are of reproductive potential must agree to avoid becoming pregnant while
receiving study drug and for 14 days after the last dose of study drug by complying
with one of the following: (1) practice abstinence from heterosexual activity OR (2)
use (or have her partner use) acceptable contraception during heterosexual activity

Exclusion Criteria:

- Evidence of decompensated liver disease

- For participants with cirrhosis, participants who are Child-Pugh Class B or C or who
have a Pugh-Turcotte (CPT) score >6

- Is co-infected with hepatitis B virus

- Has cirrhosis and liver imaging within 6 months of Day 1 showing evidence of
hepatocellular carcinoma (HCC) or is under evaluation for HCC

- Currently using or intends to use barbiturates during the treatment period of this
study

- Is a female and is pregnant or breast-feeding, or expecting to conceive or donate
eggs from Day 1 or anytime during treatment, and 14 days after the last dose of study
medication, or longer if dictated by local regulations

- Any medical condition requiring or likely to require chronic systemic administration
of corticosteroids, Tumor Necrosis Factor (TNF) antagonists, or other
immunosuppressant drugs during the course of the trial

- Evidence or history of chronic hepatitis not caused by HCV