Part of a virus which affects chimpanzees could help speed up the race to find an Aids vaccine.
Several clinical trials of vaccines are being held globally
Scientists across the world are still trying to develop a vaccine, but when one is found it will need a way of being delivered to the body.
Trials currently use human viruses, but these are less effective as the human body develops an immune response.
The joint International Aids Vaccine Initiative and GlaxoSmithKline scheme uses a virus the body will not attack.
The technique, known as the non-human primate adenovirus vaccine vector, has yet to enter clinical trials, but the initiative, which has been set up to coordinate the hunt for a vaccine, believes the partnership could speed up efforts.
Initiative president Seth Berkley hailed the partnership - the first between the public and private sector in the race to find a vaccine - as one which could lead to "real scientific collaboration".
He said, despite 20 years of failed attempts to develop a vaccine, it was still important to find a way of getting it into the body.
"We believe we ought to be thinking about access now."
International Development Secretary Hilary Benn added developing an Aids vaccine was essential for the developing world and the agreement was "critical" for enhancing research and development.
Without a vaccine, it is estimated that 5m to 6m people will be newly infected with HIV every year for the next 20 years on top of the 75m who have contracted HIV since the early 1980s.
Human trials of vaccines are being carried out in several countries, but none have yet proved to be significantly effective against the disease.
In the 20 years since the HIV was identified as the cause of Aids, around 70 human clinical trials have been carried out.
But only one vaccine has reached the advanced trial stage, and that did not show any noticeable level of efficacy.