The laboratories integrated into the ONSA network (Organization for the Sequencing and Analysis of Nucleotides) put together by FAPESP, will be participating in an international consortium which will carry out the genetic sequencing of the genome of the mosquito Anopheles gambiae, the main insect responsible for the transmission of malaria in Africa. Also, participants of the consortium are: Celera Genomics of the United States; the Pasteur Institute of France; and the European Laboratory of Molecular Biology with its headquarters in Germany, among others.
The project has the support of the Special Program of Research and Training for Tropical Diseases of the World Health Organization (WHO). The Brazilian cooperation was agreed on at a meeting which took place at the beginning of March at the Pasteur Institute in Paris. According to Dr. José Fernando Perez, the Scientific Director of FAPESP, the terms for the Brazilian participation are yet to be defined.
The project has as its objective to completely sequence, this year, the 260 million pairs of bases of the genome of the Anopheles gambiae, by using the shotgun technique perfected by Celera Genomics. The start of the sequencing will be done by Celera Genomics and by the French Center of Sequencing (Genoscope); the joining of the fragments of the genome will also be done by Celera Genomics, and the final assembling will be the responsibility of Genoscope and of the Genomic Research Institute (TIGR), among others. The ONSA network will participate in the annotation of the sequencing, together with seven other laboratories. The project also envisions the sequencing of other varieties of mosquitoes which transmit the sickness, among them the Anopheles darlingi, which exists in Brazil.
Three organisms make up the cycle of the illness: the human being, the mosquito of the Anopheles species and the protozoon which causes the illness, the Plasmodium falciparum, whose genetic sequencing is in the concluding phase in the United States. The sequencing of the genome of the mosquito, together with that of the parasite Plasmodium and of the human host, will permit the researchers to identify new mechanisms of control of the cycle of malaria.
An aggressive vector
Malaria annually hits 300 million people, mainly in the sub-saharan region, and is responsible for the deaths of 1 million children. The Anopheles gambiae is its principal vector. The incidence of the illness grows in proportion to the mosquito population, which has developed resistance to insecticides. The African mosquito is a close relative of the Anopheles darlingi , the transmitter of the illness in Brazil.
“The main difference is that the Anapheles gambiae is much more voracious and aggressive. It bites more often and for a longer length of time.” explains Marcos Boulos, Head of the Department of Infectious and Parasitic Diseases of the School of Medicine of the University of São Paulo (FMUSP). While the darlingi generally attacks at the beginning of night, the gambiae bites its victims throughout the night and until the break of day. The result is that here in Brazil the number of victims is much less – they reached 600,000 people in 1999, and the mortality rate is low. “More or less 80% of the cases are benign.” said Dr. Boulos.
The Northeast region of Brazil already lived with the Anopheles gambiae, at the beginning of the century, and around the Thirties. The mosquito was wiped out, according to Dr. Boulos, in one of the greatest Public Health victories in the country, with the support of the Rockefeller Foundation.Republish