An international team of scientists is to try to develop a wholly artificial vaccine to combat polio. The disease is very close to being eradicated, with only a few hundred cases now reported worldwide each year. The hope is that the new approach can address some shortcomings in an existing vaccine, and so help eliminate polio altogether.
The World Health Organization and the Bill & Melinda Gates Foundation are providing a $674,000 (£438,000) grant. The project was announced at the annual meeting of the American Association for the Advancement of Science in San Jose, California. Researchers in the US and the UK will participate. In Britain, this will pull in workers from Leeds, Oxford, Reading, and the Diamond synchrotron. The battle against polio is tantalisingly close to being won.
Where once there were hundreds of thousands of cases worldwide, just 350 were reported last year, and most of those were in Pakistan. But the last mile is proving to be frustrating. One reason is because the existing oral vaccine uses a weakened version of the virus as its stimulus to provoke a response and protection in the patient. Prof Dave Stuart: “We’re not able at the moment to get rid of those last few cases”
And in just a few particular individuals, this can set up an infection in the gut that then enables a reactivated virus to pass out of the body and spread to other, unvaccinated people. But if the virus particle has no genetic machinery this transmission route is closed, and the World Health Organization and the Gates Foundation is to fund the scientists to engineer just such particle for use as a replacement vaccine.
Professor Dave Stuart from Oxford University is a member of the team. “The idea of the synthetic vaccine is that it contains no genome – it’s virus free,” he told BBC News. “So it’s made, in a way, like a super-chemical, a complicated chemical, that assembles itself to look like the virus but has no way of ever replicating.” The team feels it is already some way down the road to achieving its goal because of the success it had in developing a synthetic vaccine to combat the foot and mouth disease virus (FMDV).
One of the obstacles the team had to overcome in producing the FMDV solution was to find a way to maintain the shape of the particle when it had no genetic material inside. Prof Stuart explained: “There are problems because if you try to make something that looks like the virus but doesn’t contain the genome, it tends to be more fragile. “We had to use a detailed knowledge of how the atoms in this complicated structure were arranged to then go in and do some molecular re-engineering to make it more stable, so that it could hang around long enough to induce enough protective response from the immune system.”
As well as being a professor of structural biology at Oxford, Dave Stuart is the life sciences director at the Diamond Light Source, the UK’s national synchrotron science facility. It is at Diamond that powerful X-rays are used to image these types of structures on the scale of atoms and molecules. The scientists stress that a synthetic approach is just part of the strategy required to totally eliminate polio, and they warn that vaccination would have to continue for some years beyond the last recorded case to make sure it had no chance of re-establishing itself.