Polio is on the verge of being eradicated world-wide, but even when
it has been officially declared as extinct as a disease, governments
will need to continue to vaccinate to ensure against it recurring.
Using current technology, the production of vaccine requires the
growth of enormous quantities of live virus, which is then chemically
killed, thus presenting a dangerous security risk of virus escaping into
‘New ways to provide vaccines against polio, which do not require the growth of live virus for their manufacture, have been identified.’
Despite the success of vaccines produced from 'virus-like particles'
(VLPs) for hepatitis B and human papilloma viruses, poliovirus VLPs
have proved to be too unstable to make practical vaccines.
Now, a research team at the University of Leeds has found a new way
to modify these VLPs, also known as 'empty capsids' by identifying
mutations which make their structures sufficiently stable to act as
The empty capsids change shape when warmed and become unusable as
vaccines, but the mutations identified in this research prevent these
The new stabilized VLPs are suitable as replacements for the
current killed poliovirus vaccines and can be produced in ways that do
not require the growth of live virus.
The Leeds team and collaborators say this form of vaccine, using the
newly developed stabilized VLPs, would be best used after the virus has
David Rowlands, Professor of Molecular Virology and co-leader of the
study at the University, said: "Continuing to vaccinate after polio has
been eradicated is essential to ensure against the disease recurring,
but there are significant biosafety concerns about current production
methods. Our new method of creating the vaccine has been proven to work in
lab conditions and on top of that we've proved it's actually more stable
than existing vaccines. The improved stability of these modified VLPs means that they can
be produced using bioengineering techniques without involving the growth
of live virus."
This study was a lab experiment, which shows stabilized VLPs to be
effective in a controlled environment. Further research using animals
(rats and mice) is planned, as part of the essential process of making
sure the new VLPs are safe and effective for use in humans.
Professor Nicola Stonehouse, co-leader of the study, from the
University of Leeds said: "The international drive to eradicate polio
using existing vaccines continues, but methods need to be found to
maintain vaccination safely as insurance after it appears to have been
eradicated. This is when our approach will come into its own.
"Further research is needed to refine them more but we are confident
they will work for all three forms of polio. After that we need to find
a way to manufacture them cost effectively on a large scale."