Researchers have recruited healthy volunteers to take part in a trial to find a vaccine against HIV.
St Thomas's Hospital, where the research is based
Volunteers for the eighteen month study, run by doctors at St Thomas' Hospital London, must be HIV negative.
The team at St Thomas' are working with researchers at a hospital in Nairobi, Kenya to test the safety of a potential vaccine.
The announcement of the study, carried out in conjunction with the National Aids Trust (NAT), comes after results from trials of the Vaxgen vaccine, the first Aids vaccine to be tested on humans, showed it does not protect the general population, but may protect black and Asian people.
It is estimated that 42 million people are now infected with HIV worldwide. There is no cure, and drugs to keep it under control are not universally available.
No infection risk
In the St Thomas' research, volunteers will be given four injections of the vaccine over 18 months.
They will have regular blood tests and be monitored to assess their response to the vaccine.
The vaccine they will be given is different to the Vaxgen vaccine.
It will be given in two stages. In the first, DNA of the HIV virus will be given to volunteers so the body can recognise it as a foreign body and start producing antibodies.
Then, parts of the virus will be given in a "carrier" bacteria, so it can get into the blood better.
Doctors stress that the vaccine does not contain live HIV material or any blood or blood products.
They are adamant it is impossible to become infected with HIV through being given the vaccine.
Participants in the study must be HIV negative and aged between 18 and 60.
They must have had no previous severe reaction to a vaccine and be at low risk of contracting HIV through sexual behaviour or intravenous drug use.
Women who take part must not be pregnant or intend to become pregnant during the study.
The St Thomas's research is sponsored by the International Aids Vaccine Initiative.
Dr Barry Peters, who will lead the study, said: "The number of new cases continues to rise at an alarming rate - 5 million men, women and children were infected with HIV in 2002.
"Other infectious diseases, such as smallpox and polio, have been controlled or even eliminated by vaccination programmes and many experts believe that an HIV vaccine offers the only real hope of controlling the epidemic."