My particular interests include co-infection with HIV and viral hepatitis (prevalence, transmission, natural history, immunology and response to treatment), and the use of HIV cohort studies (UK CHIC, the MRC Seroconverters Register and the UCL Partners HIV Cohort) to examine treatment outcomes and complications. Work on HPV includes treatment trials, and the use of HPV vaccines to prevent disease in groups at high risk of acquisition and disease incidence including MSM.