The objectives of the study are to determine the impact of interferon-free treatment for the hepatitis C virus (HCV) on peripheral blood immune cell phenotype and soluble immune-related proteins in blood, while controlling for genetic polymorphisms known to impact HCV-related immune responses, and to determine the impact of the therapy on the emergence of drug-resistant HCV. The study design is informed by the researchers' recent investigations of patients receiving HCV treatment. About 4% of patients who had not undergone liver transplantation experienced hepatic decompensation or another serious event. There were several cases of bacterial infection and two cases with elevated markers of autoimmune processes. These events suggest that treatment altered immune responses. About 25% of patients who had undergone liver transplantation experienced hepatic decompensation or another serious adverse event. The long term goal is to understand the pathophysiology of these complications and determine whether HCV treatment can cause an immune reconstitution syndrome in susceptible patients, while improving antimicrobial defenses in others The main questions/objectives to be addressed are (1) to determine the effect of HCV treatment on the profile of immune cells in blood as assessed by cytometry time of flight (CyTOF) multiparameter analysis, while controlling for genetic polymorphisms known to be associated with HCV-related immune responses and, (2) to determine the effect of treatment on factors/proteins in blood that may be related to immunity and inflammation.