Leukapheresis is used in Group 1 in order to obtain sufficient cells to pursue the following objectives: delineating B cell response to CD4+ T cell help, delineating CD8+ T factors associated with suppression of viral replication and normalization of immune function, characterizing natural killer function relative to HCV and/or HBV disease, and identifying biomarkers for progression of liver disease. The required number of mononuclear cells needed to perform these experiments can be easily and safely obtained using leukapheresis procedures in the Clinical Center Apheresis Unit. Participants who do not meet apheresis criteria may participate through routine blood draws to contribute to this research. All participants in Group 1 may also receive a liver biopsy at NIH (every 3 years for HIV/HCV coinfected and all HBV infected and every 5 years for HCV monoinfected subjects) to assess the progression of liver disease.