A US company is set to begin a trial of a vaccine which it claims halts the progress of multiple sclerosis.
Researchers are working towards having an MS vaccine
PharmaFrontiers is to test its tailor-made vaccine on 100 patients with MS, after a small-scale study showed promise, New Scientist reports.
MS experts have welcomed the research but urged caution because other vaccines have not been successful.
The degenerative disease attacks the nervous system and affects 2.5m people worldwide, of which 1% die each year.
In MS, immune cells destroy the myelin sheath - a protective layer - that surrounds nerve fibres in the brain and spinal cord and enables them to transmit impulses.
The vaccine being studied in the US contains inactive myelin-specific T cells - found in the immune system.
To make it, a blood sample is taken from the patient and the cells are extracted.
They are then multiplied in a lab, and treated with radiation before being re-injected into the patient.
The body's immune system then recognises these modified T cells as being damaged and attacks them, priming the body's defence system in the same way a conventionally designed vaccine would, the researchers say.
Earlier trials have shown that, in some cases, all these cells are wiped out when they are re-injected.
But the immune system also targets undamaged cells of the same kind - even though they are not damaged - because they have the same markers on their surfaces.
In one trial of 15 patients, the vaccine reduced the rate of flare-ups by 92%.
The new study will compare the progress of 100 vaccinated people who have the relapsing-remitting form of the disease with 50 who are untreated.
David McMillan, of PharmaFrontiers, said if earlier results were replicated in this study, it might be possible to slow or even halt the progress of the condition.
"If that's the case, the earlier we can do it after diagnosis, the better."
The company claims the vaccine would only have to be given four times a year.
But MS experts say much more evidence is needed before there could be confidence in this vaccine, compared to others which have been worked on.
Richard Rudick of the Mellen Center for Multiple Sclerosis in Cleveland, Ohio, said: "None have worked so far. This one may, but we don't yet know."
A spokesman for the UK's MS Society said: "This is interesting work, and we are pleased to see it taken forward in a larger study."