T-Cell Turnover Following Vaccination With MVA85A

This study examines the early immune response to a new vaccine (MVA85A) being developed to combat tuberculosis (TB).

MVA85A is a promising new vaccine designed to prevent tuberculosis (TB) by dramatically boosting pre-existing responses to BCG, the only licensed vaccine against the disease at present. In BCG vaccinated individuals it induces a strong immune response. However little is known about the evolution of that response or of the kinetics of T-cells (the immune cells that respond to the vaccine) immediately following vaccination. Crucially, the outcome of this process may determine long term protection from disease.

This study aims to define the early immune response to MVA85A and is the first to apply a safe, non-radioactive 'label' - deuterium - to measure T-cell turnover following vaccination. This labelling approach has been used successfully by the study collaborators to examine immune cell kinetics in human clinical studies in the UK over the last 8 years. The resulting data will provide insight into the immune response generated by MVA85A and aid in the future design and modification of other T-cell inducing vaccines.

Group 1 (Immune responses only)

Previous human studies of MVA85A have described the immune response to vaccination at fixed timepoints but not in between. The investigators will vaccinate four volunteers and measure immune responses daily for 14 days. This will provide important new data and aid interpretation of kinetics data from groups 2 and 3.

Groups 2 \& 3 (Labelling)

Eight volunteers will be vaccinated and then receive a timed infusion of deuterated glucose. Blood will be collected during the follow up period to determine the rates of uptake and loss of label in responding immune cells.