Scientists break genetic code of malaria mosquito
Date: 04-Oct-02
Country: USA
Author: Maggie Fox, Health and Science Correspondent
They hope their accomplishment - the fruit of a team effort involving 150 scientists in nine countries - will lead to the development of new drugs to fight the disease, vaccines to prevent it, and pesticides to kill the mosquitoes.
"This is truly a landmark day celebrating a landmark accomplishment," Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, which helped fund the research, told a news conference.
"This represents a quantum leap in our understanding of malaria," Chris Newbold of Oxford University in England told an earlier news conference in London.
Malaria, which infects 300 million to 500 million people a year, kills between 1 million and 2.7 million. Virtually all are children, mostly infants, and most live in Africa.
In the worst-hit areas, 40 percent of babies and toddlers die of the disease.
This works out to an average of 2,700 children a day, said Dr. Stephen Hoffman, formerly of Celera Genomics Inc. and now of Sanaria, both based in Maryland.
"What would happen if 2,700 children died of anything in the developed world?" he asked.
The main cause of malaria is a parasite called Plasmodium falciparum, which lives in the blood and liver. Its main carrier is the Anopheles gambiae mosquito.
Three drugs are used to treat malaria - chloroquines; quinine, which is based on the bark of Peru's cinchona tree, and artemesinins, based on the 2,000-year-old Chinese remedy Qinghaosu. In many areas, malaria now resists chloroquines.
LOW-TECH BED NETS A LATEST WEAPON
"The drugs that we use to treat the worst cases of malaria were introduced up to 2,000 years ago," Hoffman said. "The big advance of the 1990s was insecticide-impregnated bed nets. Bed nets have been used for thousands of years," he added.
"What we really want is new and better drugs and, most importantly, a vaccine."
Frank Collins of the University of Notre Dame, a mosquito expert, said he hoped the genetic code could be used to find easier ways to kill mosquitoes without hurting people or beneficial insects.
"One of the first real applications that we will see is the use of information on insecticide resistance," he said.
The scientists, from a range of public institutions, universities and one private company, Celera, published their work jointly in the rival journals Nature and Science.
They used the same methods employed to map out the human genome, and that of the mouse and the fruit fly. This gives them a rough idea of how many genes there are, but it is only a first step towards finding out what those genes do.
Malcolm Gardner of The Institute for Genomic Research, a non-profit organization in Maryland that did much of the sequencing, said it was much harder work to sort out the genome of the falciparum parasite than to decode the human genome.
"It was a huge jigsaw puzzle with many pieces that did not quite fit together," Gardner said.
With 5,300 genes, the Plasmodium falciparum genome is one of the smallest sequenced so far. The human genome has about 35,000 genes and the Anopheles gambiae mosquito genome has nearly 14,000 genes.
"The genome contains every possible vaccine target and every possible drug target," Dr Neil Hall, of Britain's Sanger Institute, told the London news conference.
FOOT ODORS
Sixty percent of the proteins made by the parasite were previously unknown. "Despite decades of research on Plasmodium, we don't perhaps know as much about this parasite as we thought we did," Gardner said.
Robert Holt of Celera, which also did much of the sequencing work, said they had identified 19 genes that could explain why Anopheles gambiae mosquitoes home in almost exclusively on people - attracted, according to mosquito experts, by distinctive foot odors. "We can design new repellants and attractants," Holt said.
It might also be possible to genetically engineer mosquitoes that do not like to bite people, or that do not carry the parasite, in the hop
