New Way Found to Attack Malaria
-------------------------------

Source:

By Paul Recer, AP Science Writer

WASHINGTON - Researchers have found a new class of drugs that in
laboratory animals can cure malaria, a mosquito-borne disease that
kills more than 2 million people annually.

The drug, called G25 by the French team that developed it, disables
the spread of the malaria parasite by blocking its ability to make
copies of itself inside the red blood cells of victims.

In laboratory studies, the researchers report Friday in the journal
Science, small doses of G25 were able to cure infections of two types
of malaria in two types of monkeys. The experiments also suggested
that the drug has a very low toxic effect, the researchers said.

"This is a very important step because they showed it worked in two
types of monkeys," said Carole Long, a malaria researcher at the Na-
tional Institute of Allergy and Infectious Diseases, one of the Na-
tional Institutes of Health.

The researchers, led by Henri J. Vial of the University of Montpel-
lier in France, report that G25 attacks malaria by interrupting a key
part of the parasite's life cycle.

Malaria spreads by a protozoan parasite that has three stages in its
life cycle.

It is introduced into a victim by a mosquito bite. As the mosquito
takes in blood, it pumps in a blood-thinning saliva that contains the
parasite.

Once inside the body, the parasite rides the bloodstream into the
liver, where it burrows and multiplies into a cluster of thousands of
parasites. The clusters burst after a few days and the new parasites
invade red blood cells and start another stage of the life cycle.

Inside the blood cell, the parasite multiplies again, making hundreds
of young parasites. When the blood cell bursts, other blood cells are
infected. Eventually, up to 70 percent of the victim's red blood
cells can be destroyed, leading to severe anemia, fever and death.

If a victim is bitten by a mosquito, the insect can pick up the para-
site along with the blood and the malaria life cycle starts over.

The G25 compound works by blocking the parasite's attempts to multi-
ply inside the blood cells.

To reproduce, the parasite must synthesize fats that become part of
the protective membrane for each of its progeny. G25 prevents the
parasite from making this membrane, thus blocking reproduction.

Vial said in Science that although G25 blocked the fat, or lipid,
synthesis of the parasite, it had no effect on the host red blood
cell.

"If you prevent the parasite itself from synthesizing lipids, it will
not survive," Vial said.

NIH researcher Long said the work is significant because it attacks
the malaria parasite in a new way. The malaria parasite is becoming
increasingly resistant to many of the drugs now used to control or
treat the disease and "we need new classes of drugs."

Long said Vial and his colleagues "have made significant advances in
moving this toward actual drug development. I am cautiously optimis-
tic."

She noted, however, that more research must be done, particularly
studies on toxicity, before the drug could be ready for human stud-
ies.

One drawback of the drug, experts said, is that it must be injected.
Vial said in Science that his team hopes within two years to develop
a version of G25 that can be taken orally.

There are an estimated 300 million to 500 million new malaria infec-
tions worldwide each year, mostly in Africa and Southeast Asia. The
majority of the 2 million who die annually from malaria are children.

--
Science: http://www.sciencemag.org
Malaria: http://www.niaid.nih.gov/factsheets/malariares.htm

--
Dr Rana Jawad Asghar
Lecturer Postgraduate Education
Department of Infectious and Tropical Diseases
London School of Hygiene and Tropical Medicine
Tel: +44-207-299-4728
mailto:[email protected]
mailto:[email protected]
http://www.DrJawad.com

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