Ngoc Pham and Astha Verma

Ngoc Pham and Astha Verma
Astha Verma and Ngoc Pham (standing) in Anderson's Latham Hall laboratory.

Fighting malaria

 

Two Virginia Tech graduate students are working from opposite ends to combat malaria, which is a vector-borne infectious disease transmitted through the bite of an infected female mosquito of the genus Anopheles.

In 2010, an estimated 216 million cases of malaria occurred worldwide and 655,000 people died, according to the Centers for Disease Control and Prevention. Although the majority of the cases occur in the African region, where a child dies every 30 seconds from the disease, about 1,500 malaria cases are diagnosed in the United States each year.

Astha Verma, a fifth-year Ph.D. student in the lab of Paul Carlier, professor of chemistry in the College of Science, is working to develop an insecticide that will combat mosquitoes more efficiently without harming humans. 

Currently, the pyrethroid-based insecticides used to coat mosquito nets are having a decreasing effect, as mosquitoes evolve and become resistant to the chemical.  Because this is the only class of insecticide approved by the World Health Organization to be used on nets, and the most common used in spraying, “there is an urgent need to explore a new class of insecticides,” Verma said.

To tackle this problem, Verma and her lab mates are studying another class of insecticides known as acetylcholinesterase inhibitors, specifically, organic compounds known as carbamates. While carbamates are currently used as agricultural pesticides and pest sprays, the resistance to carbamates is not as extensive as in the case of pyrethroids, according to Verma.  They may prove to be a valuable alternative.

“I am lucky that Dr. Carlier gave me the opportunity to work on this project,” Verma said.  “I am loving every bit of the contribution I am making. I come from a country which faces the problem of malaria. Through this research I feel I am giving back not only to my people but also to the rest of the world where the problem of malaria is severe.”

"Astha has poured herself into this project, persistently and creatively overcoming many scientific hurdles,” Carlier said. “She even learned how to raise Anopheles mosquitoes from eggs to fully emerged adults, a skill that is rare among chemists!"

Meanwhile, Ngoc Pham, a master’s student in the lab of Troy Anderson, assistant professor of entomology, studies how mosquitos are biologically able to resist insecticides.

Specifically, Pham researches P-glycoproteins, which transport compounds out of the cell and are also thought to be a cell’s first line of defense when exposed to insecticide.  Most insecticides attempt to attack the mosquito’s central nervous system, at the blood-brain barrier interface.

While P-glycoproteins are widely studied in other medically and agriculturally important insects, their interference with insecticides in mosquitoes has not been as thoroughly explored. Pham is attempting to shed light on the field by examining interactions in lab mosquitoes.  Ultimately, clarification of these interactions could help prevent mosquito resistance to insecticides.

“I feel exceptionally fortunate to be involved in such an important project,” Pham said.  “Knowing that my research can lead to a possible identification of a new resistance mechanism for mosquitoes is beyond anything I could have asked.”

"Ngoc has significantly contributed to our examination of insecticide delivery and control of vector mosquitoes,” Anderson said.  “She is an essential member of our research team, and an exceptional student and researcher."

This semester, both Verma and Pham received awards from the Division of Agrochemicals at a recent American Chemical Society meeting in Philadelphia, Pa.  Verma was awarded first place for her poster presentation titled "Five-membered ring heterocyclic carbamates and carboxamides: The quest for resistance-breaking, species-selective acetylcholinesterase inhibitors against the malaria mosquito."   Pham was awarded third place for her poster presentation titled "Evidence for P-glycoprotein modification of insecticide toxicity in vector mosquitoes."  There were a total of 20 students participating in the award competition.

Ngoc Pham and Astha Verma 2
Ngoc Pham, first left, and Astha Verma, second left, with other award recipients at the 2012 American Chemical Society meeting in Philadelphia, PA.