Every night after dinner, one of the world's top HIV vaccine researchers, Dr Pontiano Kaleebu of Uganda, leaves his family and goes back to his laboratory.

Kaleebu - like the Ugandan government - urgently wants to find a vaccine for HIV/Aids, which has infected about 1.5 million of his country's 26 million people and is considered a national emergency.

Uganda is not only the leader in Aids prevention in Africa but was also the first country to test an Aids vaccine, said Dr Seth Berkley, president and chief executive of the International Aids Vaccine Initiative (IAVI), a non-profit organisation, when he addressed the Ugandan parliamentary Aids committee on Thursday .

Uganda was the continent's pioneer of human trials of an Aids vaccine in 1999. In February, it launched a second human trial using a vaccine from the HIV strain most common in East Africa.

It took the Ugandan government just six months to give the go-ahead for tests on the vaccine which was developed by the University of Oxford, the University of Nairobi and IAVI - with Kaleebu as the principal investigator.

The same sub-type-A vaccine is being tested simultaneously in Kenya and Britain. "Kenya learnt from Uganda and moved forward quickly," said Berkley.

In South Africa, IAVI is still waiting for approval to test the vaccine after submitting an application to the Medicines Control Council about 18 months ago.

Last month the council approved the first HIV human trial of a vaccine in South Africa for the dominant sub-type-C strain.

"Developing a successful vaccine needs participants in many trials," explained Kaleebu, who works at the IAVI centre in Entebbe, which was officially opened on Friday.

This week, three HIV vaccine volunteers visited the centre for their third of four injections, a process expected to last 18 months. Until now there has been 100% compliance by the 35 volunteers in the trial (which needs another 15).

One of them, 34-year-old Paul Wetaka, is volunteering for the second time for an Aids vaccine. A soldier , he says: "HIV/Aids is an enemy to our nation and we must attack it."

The first phase of the trial tests the vaccine's safety on a small group of volunteers. The second phase, with a larger group, tests dosages and whether the vaccine triggers the appropriate immune response.

Kaleebu estimates that about 70 phase one and two trials have taken place since the first HIV vaccine trial was launched in the late 1980s. Thailand is conducting the third and final phase of a trial.

"Twenty-two years into the epidemic, there has only been one vaccine tested in the world. This is a political disaster," Berkley told the Ugandan parliament.