An innovative test to identify the best potential Aids vaccine from among other less promising products is being developed by British scientists.

Early results suggest that the test is able to detect not only whether a vaccine will generate a response from the body’s immune system, but also whether this response will actively fight HIV, The Times has learnt.

Until now there have been few means of establishing whether a vaccine is likely to work, short of large-scale clinical trials, but there are insufficient resources to take all candidate vaccines to a full trial, which can cost more than £100 million, take three to five years to carry out and involve thousands of volunteers.

The test, known as a viral inhibition assay, devised by Imperial College London and the International Aids Vaccine Initiative (IAVI), is being evaluated in a phase-one Aids vaccine trial. Early data indicates that this laboratory test has been able to distinguish between immune responses that can control HIV and those that cannot.

The test works by taking blood from uninfected patients who have been injected with a candidate vaccine, then mixing it in a lab with a live virus to see whether the immune cell responses prevent the virus from replicating.

It was developed at IAVI’s human immunology laboratory at the Chelsea and Westminster Hospital in London. Scientists hope that the assay, one of several in development, can be used to check candidate vaccines, helping to pick out the most promising for full trials while weeding out ineffective products that could prove a waste of time and money.

The project will be funded by a £40 million grant from the Department for International Development to IAVI, which operates in 24 countries, for its work on HIV research.

The findings come 25 years to the month since Margaret Heckler, President Reagan’s Secretary of Health and Human Services, announced that an Aids vaccine would be available within two years. Scientists now refuse to be drawn on a timetable, but the work could take about two decades.

The development also follows the failure of Merck’s V520 vaccine, which had shown promise in triggering an HIV-specific immune response. It was found subsequently not to protect against HIV and may even have increased some people’s susceptibility to the virus.

Jill Gilmour, IAVI’s director for clinical research, who heads the Imperial team, said that the method of testing, which closely mimics infection and immune responses in the body, appeared to be very promising so far.

“The proof of concept is there. We feel it’s pretty reliable,” Dr Gilmour said. “This is measuring something different to the current assays and arguably much more relevant. We believe it can be a key frontline strategy and that it is grounded in sound scientific hypothesis.”

She added that the test’s predictive potential could be confirmed only when a candidate vaccine showed some efficacy in larger trials.

Ivan Lewis, the International Development Minister, told The Times: “The UK Government remains fully committed to fighting the spread of HIV and that is why we are supporting projects like this.”

Seth Berkley, president of IAVI, said: “If we are able to tease out what looks promising and what doesn’t, then we have a holy grail. At the moment you get to a point where it’s a ‘crapshoot’ as to what you take forward and what you don’t.”

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