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NMSU team works to stop malaria while it's still inside mosquitoes

Malaria is still a threat in some parts of the U.S., with about 1,500 cases reported annually, according to the Centers for Disease Control and Prevention. Working to reduce that threat is a group of biology students at New Mexico State University.

NMSU graduate students Phanidhar Kukutlar, Jinjin Jiang and Dong Pei study mosquitoes in Jiannong Xu's biology laboratory. (Submitted photo by Robert Yee)

The students are exploring ways to manipulate the bacteria that lives in the gut of the mosquito, hoping to inhibit the malaria parasite inside infected mosquitoes and curb the reproductive ability of the insects.

Led by Jiannong Xu, assistant professor in the College of Arts and Sciences, students Phanidhar Kukutla, Jinjin Jiang and Dong Pei are collaborating in their study of the biology of mosquitoes.

"Malaria is responsible for the deaths of thousands of people in Africa," said Kukutla, a third-year doctoral student. "A malaria parasite needs both mosquito and human to complete its lifecycle. When a mosquito takes a blood meal from a malaria-infected person, it spreads the parasite. The parasite undergoes several developmental stages inside the mosquito and sits on the salivary glands. When the mosquito takes a blood meal from a healthy individual, that's when it injects the poisonous infectant.

"Our focus is to stop the malaria parasite while it's inside the mosquitoes so it doesn't transmit to humans. Through metagenomics, we study the bacteria inside the mosquito gut."

The research also may help reduce the spread of West Nile virus and Dengue Fever.

At this point in their research, the group knows which bacteria are associated with the mosquito through all its life stages. They are focused on female mosquitoes, which need nutrient-rich human blood to properly develop eggs.

"In blood, they get proteins, which can be used for egg production," said Pei, a first-year doctoral student. "Our red blood cells are rich in nutrition."

After the blood meal, it takes from 72 to 96 hours for the mosquitoes to fully develop eggs. On average, they produce 100 to 150 eggs each.

Jiang, third-year doctoral student, has observed mosquito egg production, or fecundity, as she refers to it, inside the lab.

"We put wet paper inside the mosquito cage so they will lay eggs there," she said. "One day after, we take out the paper and count the eggs under the microscope. We give them different treatments. I gave them paraquat, an oxidative stress inducer, to see if this chemical would affect the fecundity. It decreased the number of eggs by more than 50 percent."

In the past, the group compared lab mosquitoes to wild mosquitoes in Kenya, through a collaboration with researchers at UC Irvine. They found that the mosquito gut is selective and only core bacteria survive in the gut.

Kukutla said the group is looking at a combination of tools in the process of feeding bacteria to mosquitoes. If deprived of certain bacteria, Kukutla said, mosquitoes will be unable to promote parasite growth and also not produce as many eggs as usual.

"In the future we may modify the bacteria so that they can express anti-plasmodium molecules inside the gut," he said. "These molecules can kill the malaria parasite."
"It's important to evaluate the differences of bacteria in mosquito guts from different places," Pei said.

"It's useful to understanding which bacteria are associated with different regions, different climates and different conditions," added Kukutla.

The students have already published some of their findings in several publications, and are working on another to be published in the near future.