A new vaccine that can fight tuberculosis (TB) before and after infection has been developed by Danish scientists. It could offer protection for many years more than is now possible, writes BBC online Sunday.
TB is a huge global problem, particularly in developing countries, where access to antibiotics to treat the disease is limited. The latest vaccine, so far tested in animals, is featured in the journal Nature Medicine.
TB is a disease of the lungs, causing symptoms such as coughing, chest pains and weight loss. Untreated, it can be deadly. However, only in a small number of cases – fewer than 5 per cent – do the symptoms develop immediately after infection.
In more than 90 per cent of cases, once Mycobacterium tuberculosis, the bacterium which causes the disease, has invaded the body it changes its chemical signature, and lives in a dormant – or “latent” – state.
Usually the bacterium never emerges from this latent state, but in around 10 per cent of cases it reactivates – often years or even decades later – to trigger severe symptoms.
Current vaccines, such as the BCG vaccine, work only if given before exposure to the bacterium. They do not prevent infection, but do prevent acute symptoms and disease from emerging.
But once the bacterium has changed into its latent form it is effectively immune to the vaccine, and can bide its time, reactivating after the vaccine has ceased to have a preventative effect. If successful in human trials, the new vaccine would be able to tackle that problem.
Developed by a team at the Statens Serum Institute in Copenhagen, it combines proteins that trigger an immune response to both the active and latent forms of Mycobacterium.
With over nine million new TB cases globally each year and increasing levels of drug resistance new diagnostics, drugs and especially effective vaccines are desperately needed.
