A healthy Briton is about to become the first person to receive a potential new vaccine for the deadly Ebola virus.
The volunteer will be injected with a single benign Ebola virus protein, in a trial for a vaccine being conducted at the University of Oxford.
The protein has been combined with a 'harmless' virus which causes the common cold in chimpanzees, to create to vaccine, experts said.
Health workers in Monrovia, Liberia, where Ebola is spreading
The person, whose name has not been revealed, will be the first of 60 to receive the experimental drug in the UK trial.
The testing is part of a series of trials of potential vaccines to combat the virus, which could offer hope to thousands of people facing the illness in West Africa where an outbreak has killed around 53% of those infected.
There is currently no treatment or vaccine.
The test vaccine uses the Ebola virus protein to stimulate an immune response in the body, which could protect from Ebola infection in future.
It will not cause a person taking part in the trial to be infected, scientists said.
One of the experts involved in the trial, Edward Wright from the University of Westminster, told BBC Radio 4's Today programme that: "They are not actually being injected with the Ebola virus, it is one benign protein from this virus that has been incorporated into a harmless virus from a chimpanzee that causes the common cold in chimpanzees.
"The gene that expresses this protein, this Ebola virus protein, is incorporated into this chimpanzee virus and forms the vaccine that is going to be administered to the volunteers in this study.
"Once this virus infects the cells it leads to expression of the Ebola virus protein and this is what will hopefully stimulate the immunity in our volunteers."
Symptoms of Ebola
The vaccine, co-developed by the US National Institutes of Health and British drug company GlaxoSmithKline (GSK), targets the "Zaire species" of Ebola, which is one of the strains causing thousands of deaths in West Africa.
The first Briton known to contract the virus, volunteer nurse William Pooley, was discharged from hospital and recovered, saying he felt "very lucky".
The trials are conducted on healthy people to see whether they suffer any side effects.
The testing will also assess whether those given the jab generate a good immune response.
The vaccine has shown promising results when tested on animals. Pre-clinical research indicated that it provided protection for non-human primates exposed to Ebola without any significant adverse side effects.
The trial is being carried out by the University of Oxford
A £2.8 million grant was awarded to the Jenner Institute at the university from the Wellcome Trust, the Medical Research Council and the Department for International Development to accelerate the trials.
The funding will also allow GSK to begin manufacturing 10,000 additional doses of the vaccine at the same time as the initial clinical trials.
If it is successful, the drug will be tested in Gambia and Mali to ensure the studies take into account differences between European and West African populations.
In August, when the trial was announced, Professor Adrian Hill who is leading the research team, said: "The tragic events unfolding in Africa demand an urgent response.
"In recent years, similar investigational vaccines have safely immunised infants and adults against a range of diseases including malaria, HIV and hepatitis C. We, and all our partners on this project, are optimistic that this candidate vaccine may prove useful against Ebola."
Nearly 5,000 have been infected in Liberia, Sierra Leone, Guinea, Nigeria and Senegal since the outbreak began earlier this year.
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Ebola victims' antibodies are unable to cope with the fast-replicating virus, but the researchers hope the vaccine will give the immune system the ability to combat the infection.
Dr Wright from the University of Westminster said: "In the natural course of the disease with the Ebola virus antibodies are stimulated. However the virus replicates so quickly the body is not able to generate enough antibodies to block or inhibit the infection before it can fully take hold.
"So by giving a person this vaccine we hope that we can stimulate the production of these antibodies prior to them becoming infected so we can give them that protection."