Page last updated at 23:15 GMT, Monday, 4 August 2008 00:15 UK

Human malaria jab tests nearing

Mosquito
Malaria is a major killer

A type of malaria vaccine for humans is to be tested, following the success of trials undertaken with animals.

There is currently no vaccine for the illness, which kills between two and three million people every year.

Oxford University scientists, part of an international team, reported, in the journal Nature Medicine, that its virus-based jab worked well in mice.

Initial small-scale human safety trials of the vaccine are now expected to start next year.

In the end, the results were startling
Dr Simon Draper
Oxford University

Other researchers have been working towards an effective malaria vaccine, and some candidates are already in trials in humans in malaria-affected countries.

However, the Oxford scientists say theirs may be more effective against the "blood stage" of the illness, in which parasite numbers rise sharply in the bloodstream after bursting out of cells, causing severe illness, or death.

The scientists behind this vaccine believe that it can trigger a massive immune response against the parasite at this point.

The method involves two viruses, a common cold virus (adenovirus) and a pox virus, both of which have been engineered to be harmless in themselves, but to produce a protein on their surfaces which matches one found on the outside of the malaria parasite.

When an injection of the adenovirus was followed eight weeks later by the pox virus, the results in mice were clear-cut.

The vaccines produced two separate types of powerful immune response to these malaria "antigens", hopefully priming the immune system to respond aggressively when confronted by the malaria parasite later on.

In mice, it reduced the growth of the parasite by between 70% and 85%.

Easier to produce

Dr Simon Draper, from Oxford University, said: "In the end, the results were startling, and we could use these viruses to induce very high levels of antibodies for the first time."

He said that the viruses did not require any extra chemical to be given at the time of inoculation to boost their function, and were potentially easier to grow, and therefore cheaper to mass-produce.

These latest results, had allowed the team to secure extra funding from the Medical Research Council for next year's safety trials.

If these are successful, the vaccine's effectiveness will be tested, at first again on a small scale, then in a wider population, a process that could take some years.

Professor Alister Craig, from the Liverpool School of Hygiene and Tropical Medicine, said that a working vaccine remained some way off, but the immune response delivered in the mice was an "important step forward".

"It remains to be seen how 'generalised' this delivery system will be using other antigens and in humans but it is a significant addition to the field.

"The results of the phase one test will be of great interest to the community."


SEE ALSO
'Breakthrough' in malaria fight
14 Jul 08 |  Health

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