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Researchers unravel genetic code of malaria

Could an effective malaria vaccine be on the horizon? (http://www.msf.es)

Swiss scientists say the mapping of the genomes of the malaria parasite and its mosquito host should eventually lead to an effective vaccine.

An international research team announced on Wednesday that it had successfully unravelled the genomes.

Dr Christian Lengeler of the Swiss Tropical Institute in Basel told swissinfo that he expected "malaria vaccines [to] eventually come out of the whole parasite sequencing project".

"And we will need resistant mosquitoes which will certainly come out of the mosquito sequencing project."

He added that malaria had such an efficient transmission system that both the parasite and the mosquitoes which transmit the disease needed to be targeted.

The project, coordinated by the World Health Organisation in Geneva, aims to eventually rid the world of a disease that kills one child every 30 seconds, mostly in sub-Saharan Africa.

"We now have a wealth of information that can be used to identify new drugs, new targets for diagnostics and potentially enhance the development of vaccines," Ayoade Oduola of TDR, the Tropical Disease Research programme, told swissinfo.

Parasite

Anopheles gambiae is the most common mosquito species in Africa and passes the malaria parasite, Plasmodium falciparum, on to humans when it feeds on their blood.

The international research team sequenced the genome using the "shotgun" method which involves randomly sequencing segments of DNA from all over the genome and then connecting the segments by matching their overlaps.

New repellents, insecticides and vaccines are some of the tools it may be possible to build using information from the newly sequenced mosquito genome.

Until now, worldwide efforts to control malaria have been hampered by drug and insecticide resistance and the slow development of vaccines.

Genetically modified mosquitoes

Some researchers suggest that genetically modified mosquitoes might be an effective way to combat the disease.

Under this scenario, genetically modified insects, resistant to the malaria parasite, would be released into natural populations to slow or eliminate malaria's transmission to humans.

Such genetic modification has already been accomplished in Anopheles mosquitoes but more work needs to be done.

"No one can really predict a timeframe for this to happen and I don't think we should look before a ten year horizon but in the future there will definitely be applications," said Lengeler.

"We will be able to engineer mosquitoes that can live perfectly normally, that are biologically fit but will not have the ability any more to transmit the malaria parasite.

"And that's something very exciting which at the source would reduce the problem but we are a long way away from this step."

Devastating disease

Malaria is one of the biggest killers in the developing world. The WHO says some 300 million people suffer from malaria every year and more than a million die, most of them children in sub-Saharan Africa.

However, many experts believe these figures are too low. According to a report published this week in Nature, malaria afflicts over 500 million people and causes nearly three million deaths every year.

It has been estimated that malaria costs Africa $12 billion annually and has slowed economic growth in African countries by 1.3 per cent per year.

The decoding breakthroughs involving 150 scientists from nine countries are announced this week in the journals "Nature" and "Science".

The authors particularly identified genes that were activated when the female mosquito feeds on blood. They say insecticides and other agents, which interfere with these genes, should be helpful tools for fighting malaria.

The Anopheles mosquito was eradicated from Europe and North America half a century ago, largely through the use of pesticides such as DDT.

swissinfo, Vincent Landon


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