The vaccine currently under development by Dr McShane, known as MVA85A, works in tandem to the BCG, acting as a booster. It uses the 85A antigen, a protein found in all strains of TB, to boost the response of T cells already primed by the BCG vaccine. T cells are produced by the body's immune system to fight infection. This vaccine uses a virus as a delivery system for the protein and the results of the clinical trials to date show the highest T cell responses ever induced with a vaccine.
"This vaccine is safe and stimulates very high levels of the type of immune response we think we need to protect against TB. It is important for us to test whether or not this vaccine does work to stop people getting TB," says Dr McShane.
Following successful safety trials in The Gambia, the drug has now entered phase II trials in The Western Cape in South Africa, where the incidence of TB disease in infants is 1 in 100 (despite BCG vaccination). It has first been tested in HIV negative adult volunteers and these trials are now being stepped down into adolescents, and also into HIV infected adults. Once Dr McShane and her team are fully confident of the safety of the vaccine, and the strength of the immune response induced by the vaccine, it will be given to infants to test its efficacy. This is important as one of the target populations for a new TB vaccine is infants.
"The aim of our award is to enable Helen to demonstrate efficacy of the vaccine in a relevant population," says Dr Ted Bianco, Director of Technology Transfer at the Wellcome Trust, which is funding the trials. "There is a clear need for a new TB vaccine and so this work will have very significant healthcare implications both for the developed and developing worlds."
Commenting on the trials, Paul Sommerfeld, Chair of TB Alert, said: