Genetic vaccine 'best way to combat HIV': A British scientist believes an 'off-the-wall' approach could hold key to halting spread of Aids

DELIBERATELY infecting people with a genetically engineered version of the Aids virus may be the best way of combating the disease, a British scientist suggested yesterday.

According to Dr Susan Kingsman, of Oxford University, new genes could be transplanted into human beings, which would stop the HIV taking hold if a person became infected. She called the procedure a 'genetic vaccine', but warned that it was an 'off-the-wall' approach.

'There is going to be a change in thinking,' Dr Kingsman said. 'We're at a stage with HIV where off-the-wall things have got to be tried.' Dr Kingsman was giving a foretaste of results which are to be presented at the International Congress of Genetics on Friday. She warned that, as the numbers of people infected with HIV grew, so did the possibility that an even nastier version might evolve.

Conventional vaccines act by making the human immune system recognise and destroy body cells that have fallen victim to viral attack. But HIV's variability means that there is often nothing reliable to recognise and, moreover, the virus insinuates itself into T-cells, the very components of the immune system which are supposed to recognise the invaders.

Once the T-cells have become infected, the virus puts its genetic material into the cells' DNA. Then, when the T-cells are activated by a new infection, instead of reacting correctly, they start to produce more HIV in response to the genetic programme that the original virus inserted.

The T-cells are destroyed by their effort to make more HIV - and resistance to other infections is destroyed with them. But Dr Kingsman said: 'What about all of us having genes in our T-cells which would stop the virus taking hold. The virus works in a particular cell, so let's immunise that cell.' And the best way of getting genes into T-cells is to use a virus which has evolved to target them - HIV itself.

'We are actively trying to assemble a mini-HIV and are some way down the line to doing it,' Dr Kingsman said. In partnership with her husband Allan, also a molecular biologist at Oxford, she is trying to insert a 'therapeutic gene' into HIV.

The idea would be to infect T-cells with the mini-virus, which would then insert the therapeutic gene into the T-cells' DNA. The gene would lie inert unless the cell was infected by a pathogenic HIV. This would trigger the therapeutic gene into action, blocking the HIV. Dr Kingsman believes that tests on a product could start as early as next year.

A molecular mammogram could be used to diagnose breast cancer years before it could be detected by conventional X-ray mammograms, according to Professor Mary-Claire King, of the University of California, in Berkeley. Professor King's research aims to develop a test for breast cancer as reliable and early as that for cervical cancer.

'No woman should now die of cervical cancer. We would like to develop something as good for breast cancer,' she said.

The crucial step is to isolate the gene which is implicated in the development of the disease and Professor King believes that it will be identified before the end of the year. But she also cautioned that many further developments would be required before tests became available in the clinic.