Major step forward in thermally-stable TB vaccines
A promising TB vaccine for cattle and humans can be protected from heat damage, using a new technique developed at the University of Bath, scientists say.
The new method, called ensilication, prevents crucial vaccine components spoiling outside the fridge by ‘shrink wrapping’ the proteins in position, using layers of silica that build a ‘cage’ around the molecules.
Researchers showed that the TB antigen ag85b and a vaccine fused with the adjuvant protein Sbi, are sensitive to breakdown outside of the fridge.
They were then able to show for the first time that these vaccine components were protected from heat damage when ensilicated and kept at room temperature for long periods of time.
The findings, published in Scientific Reports, were described by researchers as a big step forward, not only in developing thermally-stable TB vaccines, but also in showing that this technique could be used for many different kinds of vaccine.
Fifty per cent of vaccines are currently discarded before use, after exposure to suboptimal temperatures. The World Health Organisation named thermostable vaccines a priority research area in its Global Vaccine Action Plan for 2011-2020.
Lead author Professor Jean van den Elsen said: “A new TB vaccine is really urgently needed to supplement or replace the existing BCG vaccine and reduce the number of TB cases and deaths – particularly as drug-resistant TB infections remain high.”
First author Ayla Wahid, added: “To make the vaccine as effective as possible it needs to be thermally-stable, or in other words not spoil outside of a fridge, which is why we’re really encouraged by these results. Cold-chain storage leads to a lot of wastage and expense which could be avoided by ensilication.”