Study of Hepatitis C Virus (HCV) Viral Kinetics in HIV/HCV and HCV Patients

All patients who participate in this study will have frequent blood drawn in order to
measure how quickly HCV virus declines. Pegylated interferon and ribavirin are not provided
by the study, but will be obtained as part of standard of care treatment for hepatitis C.
Participants must be willing to spend 48 hours in the hospital for frequent blood draws.
They will be compensated for their time.

All patients must be HCV genotype 1. All patients must have a liver biopsy prior to
enrollment into study. (This is not provided by the study).

HIV-infected patients must have a CD4 cell count>300. If HIV-infected and on antiretroviral
therapy for HIV, they must be on a stable regimen for 12 weeks. The HIV regimen can not
include didanosine (Videx).

Inclusion Criteria:

1. HCV infection, as documented by the presence of circulating levels of HCV RNA by any
RT-PCR or bDNA assay performed by a laboratory with a CLIA certification or its
equivalent within 52 weeks prior to study entry.

2. HCV RNA >1000 IU/ml.

3. Documented genotype 1 performed by any CLIA certified lab.

4. Men and women age 18 to 65 years.

5. Ability and willingness of subject or legal guardian/representative to give written
informed consent.

6. Female study volunteers of reproductive potential must be willing to use two methods
of birth control in order to prevent pregnancy while on IFN/RBV.

For HIV infected patients:

1. HIV-1 infection, as documented by any licensed ELISA test kit and confirmed by
Western blot at any time prior to study entry. HIV-1 culture, HIV-1 antigen, plasma
HIV-1 RNA, or a second antibody test by a method other than ELISA is acceptable as an
alternative confirmatory test.

2. CD4+ cell count ³ 300 cells/mm3 within the prior 12 weeks at a CLIA certified lab or
its equivalent.

3. Subject may be HAART naïve, but if on HAART should be on a stable regimen for 12
weeks The HAART regimen cannot include didanosine (Videx). Interaction with ribavirin
and didanosine has led to fatal hyperlactatemia in a few patients.

Exclusion Criteria:

1. Unwilling to be admitted for 48 hours for serial blood draws for virology studies.

2. Hepatitis B surface antigen (HBsAg) positivity.

3. Prior IFN -based therapy.

Additional Exclusion for HIV-infected:

1. Current symptomatic HIV disease (i.e., AIDS-defining illnesses).

2. HAART regimen that contains Videx (Didanosine). Subject may previously have been on
didanosine but if on a new HAART regimen should be on the regimen for 12 weeks.