We propose three major analyses. First, we will perform gene expression profiling in PBMC preparations provided by Dr. Kamal from patients with acute HCV. These PBMC preparations are being performed as part of ongoing studies headed by Dr. Kamal. Second, we will use microarray analysis to describe the hepatic genes which are altered by HCV infection in the post-transplant liver graft in response to infection by HCV. For this we will use portions of liver biopsies already being taken as part of routine post-transplant clinical care. Third, we will prepare PBMCs from patients with chronic HCV and from these determine gene expression profiles. Not only are these a critical comparison to acute HCV, but they will also act as the basis for predicting outcomes of treatment in chronic HCV.