Slotman Lab Receives Grant to Study How Mosquito Species Target Human Hosts
Dr. Michel Slotman, right, with Slotman Lab postdoctoral research associate Dr. Theresa Hodges.
An Anopheles gambiae mosquito feeding. Anopheles gambiae mosquitoes are the primary vectors of malaria to humans in the sub-Saharan region of Africa.
Slotman lab post-doctoral research associate Dr Giri Athrey at a microscope in Dr. Willem Takken's lab at Wageningen University in The Netherlands.Texas A&M Entomology assistant professor Michel Slotman is hoping to find out how Africa's primary malaria vector is able to select humans as their almost exclusive hosts. This curiosity into this unusual trait of the mosquito, Anopheles gambiae , has landed Slotman’s lab a 4-year research grant by the National Institutes of Health this summer.
Anopheles gambiae populations are found in sub-Saharan Africa and feed almost exclusively on humans. Slotman said this unusual trait has made Anopheles gambiae remarkably efficient in its ability to transmit the disease between humans.
Slotman hopes to understand what genes An. gambiae uses to identify humans versus non-human hosts. Finding this connection, he said, will aid the development of more effective methods of controlling malaria in Africa.
The disease exerts an enormous toll on this continent, where 90% of all malaria cases occur. Based on reductions in GNP (Gross National Product) per capita, it has been estimated that the long term economic cost of malaria in 31 African countries between 1980 and 1995 is on the order of 74 billion dollars.
Malaria also has long-term demographic effects that reduce people's ability to prosper. But the real tragedy of course is that hundreds of thousands of African children die every year of malaria, which, given adequate resources, is a largely preventable disease, Slotman said.
Previous studies have shown that mosquitoes find their hosts by using their sense of smell . Slotman lab is targeting the 136 genes thought to be involved in Anopheles gambiae's olfactory system. Even though the function and expression patterns of some of these genes have been characterized, Slotman said that the genetic basis of host preference for humans has not yet been identified.
Slotman‘s lab, along with collaborator Prof. Willem Takken at Wageningen University in The Netherlands, is using various approaches, including genetic mapping studies using Anopheles gambiae and its sister species Anopheles quadriannulatus, which does not prefer humans. Additionally, evolutionary genetic analyses and comparative gene expression approaches will be employed to identify the human preference genes.
Once Slotman’s lab has identified the olfaction receptors or olfaction binding proteins that are specifically involved in the recognition of humans, this information may be used to develop specific and efficient repellents or attractants that target these molecules.
Additionally, the genes that affect this mosquito's host-seeking behavior may also be good candidates for transgenic mosquito technology. Many researchers hope that this will one day allow us to replace natural Anopheles gambiae populations with ones that do not transmit malaria.