The hunt for a vaccine for HIV is perhaps the most urgent - and the most frustrating - project in modern medicine. Almost 30 years after the virus was identified, we have had some success in managing HIV and Aids, once contracted - but progress towards finding a full-blown vaccine remains painfully slow. Which is why a group of eminent Aids scientists has made the controversial suggestion that we should, in effect, rip up the scientific rule book. Read the article.