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Last Updated: Tuesday, 16 December, 2003, 02:14 GMT
Hope for better malaria vaccine
Mosquito
Malaria kills millions each year
Human trials of a new type of malaria vaccine are planned for next year after encouraging results in mice.

Oxford University scientists are using a combination of techniques to boost the effectiveness of their vaccine, which will be tested on volunteers.

Research published on Tuesday revealed that their formula, carried into the body on a virus, produced a strong immune response in mice.

No fully effective malaria vaccine has yet been produced by scientists.

The disease is caused by the parasite Plasmodium, carried by mosquitoes and endemic in many countries of the world.

It remains an important cause of early death - and a significant risk to travellers, who currently face lengthy courses of antimalaria tablets prior to travel.

Liver attack

Scientists hope to prevent dangerous infection by pre-training the body's immune system to attack the parasite as soon as it appears in the liver.

Nothing quite like this has been tried before against malaria.
Dr Sarah Gilbert, Oxford University
To do this, a vaccine presents samples of protein chemicals found in Plasmodium, which are taken up by the immune system and prime it to respond aggressively when the parasite arrives and the same proteins are identified.

However, this has proved difficult because there are many different varieties of Plasmodium, each with subtly different proteins, the majority of which are capable of evading any vaccine which focuses only on one protein.

To overcome this, Dr Eric Prieur and his colleagues managed to join up a string of several different proteins taken both from the surface coat of Plasmodium, and other locations in the parasite.

This raises the chances that any variety of Plasmodium encountered will carry one or more of these proteins, triggering an immune attack.

Killer cells

The mouse experiments produced a good sized reaction from "killer T cells" - the destructive immune cells needed to destroy Plasmodium.

Dr Sarah Gilbert, another author of the research paper, published in the journal Proceedings of the National Academy of Sciences, said that scientists were confident that human trials using volunteers would start towards the end of 2004.

She said: "The proteins involved are all ones that the parasite produces while it is in the liver.

"If we can clear the parasite in the liver, there will be no symptoms of malaria.

"Nothing quite like this has been tried before against malaria."


SEE ALSO:
Malaria
08 Feb 03  |  Medical notes
Find could boost malaria fight
20 Aug 03  |  Health


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