The major goal of this project is to identify the role of the immune responses in the emergence of protease inhibitor mutants during therapy.

Objective 1: Evaluate the role of the immune responses in determining the emergence of HCV NS3 resistance mutation during protease inhibitor therapy

Hypothesis 1 (HT 1): Low HLA binding to peptides containing protease inhibitor resistance mutations is associated with the emergence of protease inhibitor mutants during therapy and failure of the treatment.

Hypothesis 2 (HT 2): A hole in T cell repertoire may allow emergence of protease inhibitor mutants during protease inhibitor therapy which leads to loss of the immune responses to these mutants and failure of treatment.

Inclusion Criteria: All chronically HCV-infected patients who fail peg-IFN and RBV therapy and are eligible for combined treatment with PI therapy will be enrolled. Briefly, this includes:

1. Male or female
2. Age 18 to 65
3. Chronic HCV infection evidenced by liver biopsy or persistent HCV viremia for >6 months
4. Treatment experienced and classified as non-responder or relapser to prior interferon-based therapy.

Exclusion criteria:

1. Treatment naïve chronically HCV-infected patients.
2. Patients with a history of inflammatory bowel diseases (IBD) or suspected IBD, autoimmune diseases, including rheumatoid arthritis, and any patients on systemic immunomodulators.
3. Pregnancy
4. HIV

Investigators plan to enroll 20 human subjects with chronic hepatitis C virus infection from the outpatient clinic at the University of Cincinnati College of Medicine.

chronically HCV-infected patients who fail the standard peg-IFN and Ribavirin (RBV) therapy (NR)