Scientists are planning to use a modified version of HIV in the battle to treat cystic fibrosis. If the experiments are successful, researchers hope to use the virus one day to cure babies of the condition while they are still developing in the womb.

Cystic fibrosis, a debilitating disease that clogs the lungs with mucus, is the most common life-threatening inherited disease in the UK, affecting more than 7,500 people, and there is currently no cure. Researchers at University College London have been working on ways to treat it by replacing a faulty gene. Their work involves developing vectors - viruses that can successfully carry the correct version of a gene into the diseased body cells.

Suzie Buckley, the geneticist at UCL who developed the new HIV vector, will present her research at the British Society for Gene Therapy conference which begins today in Warwick. The vector, which uses a disabled version of HIV to prevent it from causing any disease itself, has already been shown to deliver genetic material efficiently to the lungs of adult mice.

Another disease which looks ready to benefit from gene therapy techniques is severe combined immunodeficiency, a condition in which babies are born without an immune system. Bobby Gaspar, of Great Ormond Street hospital in London, who will also present his latest work at the meeting in Warwick, has used a genetic approach to treating the disease. Dr Gaspar has treated 13 children so far, all of whom, he said, are now living normal lives.