This study is designed to evaluate the safety of MVA85A in healthy volunteers in the UK who are infected with HIV. In phase I studies, a single vaccination with MVA85A, when administered at a dose of 5 x 10^7pfu intradermally, has been shown to be safe in both mycobacterially naïve individuals, those previously vaccinated with BCG and latently infected individuals. Additionally, 5 x 10^7 pfu MVA containing HIV antigens administered twice, 4 weeks apart, in HIV positive individuals, is safe. We will use 5 x 107 pfu MVA85A intradermally in this study. Subjects will be identified from HIV clinics in the Oxford Radcliffe Hospitals NHS Trust and also from Swindon and Marlborough NHS Trust and St. Mary's Hospital NHS Trust if our recruitment targets are not met.