HCV transgenic mice expressing the full-length HCV polyprotein [12] were used at 3 months of age. Only male mice were used in this study. All mice were kept in a barrier facility with a 12hr dark-light cycle, given food and water ad libitum, and maintained in microisolators with a constant temperature between 20uC and 26uC. All animal procedures were reviewed and approved by the IACUC committee at the VA Palo Alto Health Care System and in accordance with the PHS Policy on Humane Care and Use of Laboratory Animals.