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Biologists spot origin of drug resistance in malaria
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Copyright ) 1997 Nando.net
Copyright ) 1997 Reuters
Malaria kills 300,000 Nigerians every year
BOSTON (November 26, 1997 5:23 p.m. EST http://www.nando.net) -
Researchers in Friday's edition of the journal "Cell" report they have
pinpointed a chunk of genetic material that makes the malaria parasite
resistant to a primary drug used to fight the infection that afflicts
300 million people annually.
Malaria is passed between people through blood carried by mosquitos.
The research also confirms that resistance to the drug, chloroquine,
developed independently in South America and Southeast Asia about 40
years ago.
About 300 million people worldwide are affected by malaria each year,
"Cell" reported. Although it can be prevented by using drugs like
chloroquine, the disease remains an important threat to people who live
in warm climates and travelers who visit them.
Years ago, chloroquine was the primary weapon in the effort to eradicate
malaria, which causes severe fever and can be fatal if it worsens to
include the kidneys, brain, and liver.
But 10 years of exposure to the drug allowed the single-celled parasite
to develop a resistance to choloroquine. Researchers hope that by
locating the source of the resistance, scientists may be able to find a
way to overcome it.
"My crystal ball has always been cracked on this one, but my dream --
and this discovery may help make it a reality -- is to take the protein
(made from the recipe on the resistant gene) and use it to screen for
new compounds against malaria," said Thomas Wellems, an author and chief
of the malaria genetics section of the National Institute of Allergy and
Infectious Diseases.
"If our hypothesis is right and we get companies interested, a drug
could be found fairly quickly," Wellems said.
The Cell study identifies the source of the resistance as a chunk of
genetic material located on the parasite's seventh largest chromosome.
The region covers 0.13 percent of the genetic material in the parasite's
14 chromosomes.
Called "cg2," there are two variations of the resistant gene, one which
apparently originated in Indochina and spread to Africa, and the other
from samples that originated in South America.
The idea that resistance developed in two locations "is based on
historical data, and our genetics data seem to support that. Both
continents were, at the time, using chloroquine extensively," said
Xin-zhuan Su, a biochemist in Wellems' lab who has spent the last five
years in a "very intensive" search to find the source of the resistance.
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