Scientists have developed a revolutionary vaccine that could protect billions of people against the world's deadliest disease: malaria. The team - whose results were published in the journal Nature Medicine last week - have created a vaccine that provided complete protection when tested on animals.

Now the group, which includes British, Irish, French and US researchers, is preparing to launch human vaccine trials. 'The crucial point about the technology we have developed to create this vaccine is that it could be used not just to take on malaria but to fight other diseases for which we still have no vaccine, for example HIV,' said project leader Simon Draper of Oxford University.

Malaria infects more than 500 million people every year and kills two to three million, most of them young children living in sub-Saharan Africa and South East Asia. The disease is a key cause of poverty and a major hindrance to economic development.

People become infected when bitten by a mosquito carrying the malaria parasite. The parasite migrates to the liver, then erupts to spread through the bloodstream, destroying red blood corpuscles which carry oxygen from lungs to muscles. Symptoms include respiratory problems, anaemia and brain damage. If untreated, patients often slip into a coma and die.

Anti-malarial drugs are effective, but too expensive for poor countries. So to develop a one-off vaccine scientists have concentrated on two approaches. The first uses deactivated - or attenuated - parasites in order to trigger immune responses. The second involves isolating just one piece of the parasite's protein coat. This can then be grown in genetically modified bacteria and injected into individuals.

To date, however, neither approach - although effective with the majority of diseases - has worked with malaria. So Draper and his team - funded by Britain's Medical Research Council and the Wellcome Trust - took a completely different approach.

'We used a virus - the adenovirus that causes the common cold - which we genetically engineered so it contained a piece of the malaria parasite's coat,' Draper said. 'If you inject this modified virus into the bloodstream, it triggers the manufacture of antibodies - a special form of immune defence - that will attack malaria parasites.

'This is the first time that modified viruses have been used to trigger antibodies, which are the best form of immune defence for blocking malarial parasites. We have made it work in animals, and now we are building vaccine stocks so we can carry out trials in humans in a few months, first to show the technique is safe, and later to demonstrate that it is as effective as it is in animals at protecting against malaria.'