Infectious diseases such as HIV, hepatitis B and C, affect hundreds of millions of people worldwide. Our group works on the immune response to these infections, focusing on both the host and the pathogen. As there is currently no vaccine to prevent hepatitis C infection, many of our projects have addressed aspects of chronic hepatitis C virus (HCV) infection and vaccine responses. In addition, our group also looks at a range of viruses and bacteria. Overall our main contributions to date have been to define mechanisms of viral persistence, including: T cell escape, antagonism, original antigen sin, integration of non-retroviral RNA viruses; to define the key features of successful immune responses against HCV, leading to trials of a T cell vaccine; and to define the distinctive CD161+ T cell population, which dominates in the human liver.