Author: Falishia Sloan
Institution: Eastern Virginia Medical School
Date: June 2007
In research recently released in Science, scientists at Imperial College have identified the genes present in the Aedes aegypti mosquito's immune system that allows it to transmit deadly viral diseases to humans.
The research, whose senior author was Dr. George Christophides of Imperial's Division of Cell and Molecular Biology, was revolutionary in that it was the first of its kind conducted on the recently sequenced genome of A. aegypti, also featured in Science. Researchers discovered that the genes involved in the A. aegypti mosquito's immune system evolve quicker than their other genes. In all, over 350 genes within the immune system of A. aegypti were identified.
In the study, the research team led by Robert Waterhouse, a PhD student at Imperial, compared the genes in the Aedes mosquito that dealt with immunity to comparable genes of a simple fruit fly and the mosquito known to transmit malaria, the Anopheles mosquito. While observing similarities, the team also noticed many differences between the immunity genes, and it is these differences that the scientists want to focus on to explain why different species of mosquitoes transmit malaria and dengue and yellow fevers.
"Our study has revealed the genetic landscape' made by parts of this mosquito's newly-sequenced genome which are involved with immunity," Christophides said. "By working to understand as much as possible about these genes, and the way they interact with specific pathogens, we hope to gain a more complete understanding of the mechanisms by which a pathogen either survives inside the insect body, or is killed by the insect's defenses."
Scientists generally believe that the immune system of mosquitoes plays a significant role in the transmission of viruses that cause worldwide diseases. Scientists at Imperial College had already learned that the immune system of other mosquitoes had the capability of allowing or blocking malaria parasite transmission.
"This study made us realize that the immune systems of insects are not static but evolve and differentiate rapidly," Christophides said, "most likely in response to the different pathogens which each insect species encounters."
Another participant in the study, senior researcher of Imperial's immunogenomics lab and co-author of the paper Dr. Fotis Kafatos, further discussed implications of the research.
"Understanding the genetics behind pathogen/immune system interactions in disease vector mosquitoes may help us understand why, for example, some types of mosquitoes can transmit a particular human pathogen while others cannot," Kafatos explained. "If those that cannot have evolved an effective immune system that fights off the pathogen, we may be able to use this knowledge to enhance specific reactions of the immune systems in other mosquitoes to control the spread of the disease."
Future research possibilities in this area include establishing whether some of the newly identified genes in the Aedes mosquito have the same immune system properties as those discovered in other mosquitoes that allow them to block or allow disease transmission.
Another possibility would be to discover how to effectively prevent disease transmission from the mosquitoes to humans by affecting the gene activity and aiding mosquitoes in fighting off viruses.
Written by Falishia Sloan