Researchers find new way to attack malaria

A Zambian boy sits inside a mosquito net offered by the Roll Back Malaria Zambezi Expedition in Matongo village, about 60 km (37 miles) from Livingstone, April 23, 2008.

LONDON (Reuters) - Danish and U.S. researchers said on Tuesday they have found a way to way to attack malaria by knocking out a gene that helps malaria parasites reproduce inside mosquitoes.

The gene -- whose function was previously unknown -- allows the parasite to develop an egg-like structure called an oocyst, which spawns new infectious parasites, the researchers reported in the Proceedings of the National Academy of Sciences.

"When you take away the gene you see the effect of missing that gene on the parasite," said Dan Klaerke, a physiologist at the University of Copenhagen who worked on the study.

His team looked at a malaria parasite that infects mice and is similar to the species that target humans.

Malaria infects between 300 million and 500 million people each year, mainly in Africa. The disease kills about 1 million people each year, including a child every 30 seconds.

Malaria is difficult to fight because its complex life cycle allows the parasite to evade drugs and vaccines. The tiny parasites live and reproduce inside mosquitoes, which spread them when they bite animals or people.

Last week, British researchers showed how malaria parasites can fine-tune the number of male and female offspring they produce to maximize the odds of infecting another host.

The disease has become resistant to some drugs and work on a vaccine has been slow. One effective treatment is Novartis AG's Coartem, currently the gold standard in malaria care.

The researchers, who included Nirbay Kumar of Johns Hopkins University in the United States, focused on the function of the potassium channels in the parasites.

Every animal and plant cell contains these ion channels -- a type of doorway that helps provide the electrical charge that power nerves, muscles and the heart in animals.

The team discovered two new such channels in parasites, and using the knock-out technology, discovered what they controlled, Klaerke said.

Stopping the parasites from reproducing is important because an infected mosquito is unable to transmit malaria if it cannot reproduce, Klaerke said.

The researchers are now examining whether drugs could target shutting down the potassium channels, he added.

"The practical discovery may be that blockage of this channel may make the parasite more susceptible to known drugs," Klaerke said.

(Reporting by Michael Kahn; Editing by Giles Elgood)