Genome sequencing raises malaria hope
New mosquito repellants, insecticides and malaria vaccines are some of the malaria-fighting tools that could be developed using information from the newly sequenced genomes. Malaria affects more than 500 million people worldwide, and causes nearly 3 million deaths each year, more than 90 per cent of which occur in sub-Saharan Africa.
An international team of more than a hundred researchers from more than a dozen laboratories contributed to the sequencing of the mosquito species Anopheles gambiae, which is published this week in the journal Science. The genome of the malaria parasite, Plasmodium falciparum has been published simultaneously in the journal Nature by a group of researchers led by Malcolm Gardner of the Institute for Genomic Research, Rockville, United States.
”New malaria control techniques are desperately needed in Africa and the Anopheles genome has an important part to play in fighting this disease,” says the lead researcher on the mosquito genome, Robert A. Holt of Celera Genomics.
According to Editor-in-Chief of Science Donald Kennedy, ”malaria in Africa is on the rise, as malaria parasites have developed resistance to insecticides. Knowing the mosquito genome may help researchers identify genes involved in the insects’s ability to host the parasites or to locate a human to infect.”
A. gambiae, the most common mosquito species in Africa, passes the malaria parasite P. faliciparum on to humans when it feeds on their blood. To sequence the A. gambiae genome, Holt and colleagues used the ‘shotgun’ method, which involves randomly sequencing segments of DNA from the entire genome and then connecting the segments by matching their overlaps. The assembled genome sequence is 278 megabases long (each megabase equals one million nucleotides, the basic units of DNA).
Using software programmes to identify likely genes in the sequence, Holt’s team has made what it calls the “first approximation” of the genes’ general function. The entire Anopheles genome assembly has been submitted to the publicly available database, Genbank.
For malaria patients in Africa, the news should be encouraging, according to Thomas Egwang, director general of Med Biotech Laboratories in Uganda. “The genome data will accelerate the discovery, validation and implementation of new tools for malaria control,” he says. “This is an early Christmas gift to all African children and pregnant women.”
Chloroquine was the drug of choice against malaria for much of the 20th century, distributed around the globe in massive quantities and even included in the salt supply of some countries. But chloroquine resistance is now evident in four human malaria parasite species and the search continues for alternative antimalarial drugs.
Egwang calls on African researchers to use the new information provided in the genome sequences to develop new, effective means of confronting malaria. “They must convince their leaders about the importance of investing massive funds into post-genomics approaches which exploit this information,” he says. “[And] they must master the art of science communication in order to obtain adequate funding from their own governments in the face of competing national interests such as defence and poverty alleviation programmes.”
Link to Nature research paper ‘Genome sequence of the human malaria parasite Plasmodium falciparum’ by Malcolm Gardner et al.
Link to Science research paper ‘The Genome Sequence of the Malaria Mosquito Anopheles gambiae’ by Robert A. Holt et al.
Link to Nature Focus on Malaria (including freely available genome sequences and state-of-the-art global genomic analysis of the primary sequence).
Link to Science special issue preview on the mosquito genome.
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