One of the deadliest killers on the planet, a tiny vampire known as Anopheles gambiae, is becoming more dangerous. The African mosquito that spreads most of the world’s malaria has developed resistance to chloroquine, the drug traditionally used to treat the disease, and there are signs it is becoming resistant to the insecticide used against it as well. Unless a new strategy is devised to combat malaria, a monstrous public health disaster looms on the horizon. That ominous backdrop underscores the work going on in the lab shared by Frank Collins and Nora Besansky, scientists who joined the ND faculty about two years ago by way of the National Institutes of Health and the Center for Disease Control.
Genetic control is seen as the next line of defense, and the work of the husband-and-wife Notre Dame biologists is central to that strategy. The idea is to genetically engineer Anopheles gambiae so that either it no longer transmits the malaria protozoan or that it prefers a host other than human beings, and then to replace the wild mosquito with this new version. Before you can have genetic control, however, you must know which DNA does what and whether it is transmitted throughout the population — which is where Collins and Besansky come in.
Collins, the George and Winifred Clark Professor of Biology, was one of the first entymologists to study the malaria-transmitting mosquito on the molecular level, developing now widely used genetic mapping techniques in the process. Meanwhile, Besansky, an associate professor of biology, is interested in the evolution of populations.
Collins began studying Anopheles gambiae in the early 1980s when he was a research scientist at the National Institutes of Health. While at NIH where he also met his wife, who then was a technician, Collins isolated a strain of the African mosquito able to kill the malaria parasite. “Mosquitoes have an immune system of sorts,” he explains. “If they are infected with foreign protozoa their body reacts to kill the invader, typically by encapsulating it. But for some reason ‘wild’ Anopheles gambiae doesn’t recognize the malaria protozoa and so passes it on.” Since that initial work, Collins has been searching to discover the biochemical basis for that recognition. “I want to know what this mosquito is really doing on a molecular level,” he says.
With a collaborator at another institution, the Clark Professor is attempting to determine which gene controls the mosquito’s immune response. “We know there’s one major gene involved and a couple of minor ones.” He also is using the same mapping tools to understand the basis of insecticide resistance and is developing the techniques needed to genetically engineer the mosquito.
Besansky, meanwhile, among other things has been comparing the DNA from various gambiae populations in West Africa to determine whether it is true, as some scientists suspect, that they are not interbreeding. “It’s important to know, because it has implications for controlling malaria,” she says. If they are not freely interbreeding that could thwart efforts to replace the disease-spreading population.
Collins and Bessansky admit they take their work home with them. “Even though we are working on vastly different questions, there is a certain synergy,” Besansky observes. “We love to talk about this stuff, and we each benefit by working on the same organism.”