It's the year 2050, and you're on safari in Africa. While scoping out the local wildlife, you feel a small prick on your arm and look down to see a mosquito flying away, just before your hand smacks the place where it had been feasting.
"Oh no!" you think, suddenly realizing you forgot to get the malaria vaccination. "Don't worry," your guide tells you, laughing. "Mosquitoes haven't been able to carry malaria for years."
You might laugh at this story now, but it may be reality soon. Researchers at the Bloomberg School of Public Health in the Department of Molecular Microbiology and Immunology have genetically engineered mosquitoes that are resistant to malaria.
Malaria is caused by a group of parasites in the genus Plasmodium. Mosquitoes carry the parasites, which are transmitted from mice or other animals to humans when female mosquitoes bite through the skin to drink blood.
One day, researchers hope to replace wild-type mosquitoes with engineered mosquitoes. The spread of malaria could be slowed or halted by this technique: if the majority of mosquitoes in the wild can not carry the Plasmodium parasite, infection rates for humans will decline dramatically.
The results, published in the Proceedings of the National Academy of Sciences, show that not only do these mosquitoes resist malaria better than wild-type mosquitoes in nature, but they produce more eggs and live longer.
In the study, scientists mixed together a population of wild-type mosquitoes with those genetically engineered with the malaria-resistant gene. All the mosquitoes were allowed to feast on mice infected with the malaria parasite.
After multiple generations were allowed to reproduce, the results showed that there were more genetically-engineered mosquitoes than wild-type ones. This finding indicates that the transgenic mosquitoes were better able to reproduce than their normal counterparts.
Marcelo-Jacobs Lorena, a lead author of the paper, says, "It was previously believed that transgenic mosquitoes are weaker (less fit) than their non-transgenic counterparts. Our findings suggest that when fed on malaria-infected blood, the malaria-resistant transgenic mosquitoes actually have an advantage over non-transgenics. It may therefore be easier than previously thought to introduce genes that confer malaria resistance into wild mosquito populations."
The finding that these transgenic mosquitoes are more fit than wild-type mosquitoes gives hope to researchers that they may one day be a viable solution to the problem of malaria. If the transgenic mosquitoes are to provide relief from malaria once released into the wild, they need to have a better chance of survival than the normal insects.
There are concerns with the research, however. When fed blood that was not infected with malaria, both mosquitoes fared equally well. This could prove to be a problem because transgenic mosquitoes would have to show better fitness feeding on any type of blood, not just malaria-infected blood, if they are to replace wild-type mosquitoes.
According to the Centers for Disease Control and Prevention, 2.7 million people die of malaria each year. 75 percent of them are African children. Moreno and the rest of the team at the School of Public Health are working to make transgenic mosquitoes in the wild a reality as a solution to this problem.
Moreno comments, "While the advantage that the transgenic mosquitoes have over their non-transgenic counterparts is significant, it is not sufficient to drive the resistance genes into mosquito populations in the field. A high priority at the moment is to develop methods to accomplish this goal."
Keith Parent `07, a political science major and Africana studies minor, says of this development: "It's clear from discussions on an international level that malaria represents an unprecedented issue of global proportions. It's also clear that ... a breakthrough of this magnitude could not only help governments and communities within the African continent but also all of mankind."
