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Chimpanzee virus-created malaria vaccine trialled

01/02/2008

The first trials testing a malaria vaccine created with a virus found in chimpanzees are to take place in the UK.

It is the first time researchers have used a chimpanzee virus to boost the efficacy of the vaccine.

Malaria is one of the world's deadliest killers, causing the deaths of over a million people each year, but as yet there is no vaccine against the disease.

Women and children in Africa and south-east Asia are the most at risk.

Difficulties creating a vaccine result in part from the parasites responsible for infection living inside live cells, where they cannot be reached by antibodies.

Researchers at the University of Oxford have developed a vaccine which uses a genetically modified chimpanzee adenovirus to produce the malaria antigen and to stimulate a response to the vaccine in the body.

Adenoviruses are thought to be particularly potent for increasing the immune response to the malaria vaccine.

But becauses human adenoviruses, which cause diseases including the common cold and gastroenteritis, are widespread most people have developed some immunity towards them.

Scientists behind the latest malaria vaccine believe using a chimpanzee adenovirus ensures that the recipient is unlikely to have resistance to this part of the vaccine.

"Chimpanzees have their own set of adenoviruses which rarely infect humans, so we have not built up immunity to them," said virologist Dr Sarah Gilbert at Oxford University's Jenner Institute.

"This is why we have chosen such a virus to form the backbone of the new vaccine."

More volunteers to trial the vaccine are being sought by the university. Researchers say because the adenovirus is removed there is no danger that the original chimpanzee virus will be transmitted to the humans.

"We urgently need a vaccine to help in the fight against this deadly killer," said Professor Adrian Hill, a Wellcome Trust principal research fellow who will lead the trials.

"Malaria parasites are able to outwit our immune system by hiding out in the body's cells, however. Finding a way to generate enough immune cells and antibodies to identify and destroy the parasites will be the key to preventing infection."