Biochemists bite back

During the hot summer months in Houston, citronella candles, bug sprays, zappers and fly swatters sell like hotcakes so people can keep mosquitos at bay. However, students at a local university invite the pests into their backyards. Using large barrel traps, they have collected hundreds of mosquitos to investigate what viruses the insects are spreading in the Bayou City and across the Lone Star State.

Mosquitos, ticks and fleas, also known as vectors, carry myriad viruses, bacteria and parasites. These pests transmit pathogens to animals and humans via their saliva during a bite. But don’t worry too much: The chance of developing a viral disease, such as West Nile virus, after a mosquito bite is just one in 300 in the U.S.

Ava Ngo

Left: Undergraduate researcher William Maldonado performs DNA and RNA extractions on mosquito samples in the lab at the University of St. Thomas in Houston. Right: University of St. Thomas undergraduate researcher Angelika Jordan sets up a mosquito trap in her backyard in Houston.

However, the mosquito population in North America has increased 10-fold over the past 50 years due to climate change. Now, health officials are seeing some viruses that previously were found in only tropical regions a decade ago pop up across the southern U.S.

“Even though the field of microbiology has been around for centuries, it's only now that we're beginning to uncover much of its diversity,” Maia Larios, professor and chair of biology at the University of St. Thomas and project supervisor, said.

Therefore, researchers at UST began to do their part in tracking mosquito species and the viruses they carry across Houston.

“Knowing where viruses exist and how they might move to new environments or new hosts is important for better surveillance, tracking and prevention of known diseases, as well as emergent and novel diseases that might challenge humans in the future,” Ava Ngo, an undergraduate researcher at UST, said.

Ngo worked with fellow undergraduates Angelika Jordan and William Maldonado to capture mosquitos across town. Their traps are designed to simulate a human being by imitating the visual signals and convection currents of a body.

After capturing the mosquitos and extracting their RNA and DNA, the team worked with the UST computer science department to perform metagenomics on the samples. The hundreds of mosquitos they gathered collectively carried dozens of viruses, such as West Nile virus, Dengue virus and others.

According to Rosemarie Rosell, a professor of biology at UST and project supervisor, the most surprising virus they uncovered was Lauvirus, which is native to Southeast Asia.

“Lauvirus interests me the most, because Houston is right on the shipping channel,” Rosell said.

Left to right, undergraduate researcher Ava Ngo, project supervisor and department chair Maia Larios and project supervisor and professor Rosemarie Rosell.

The Houston Ship Channel stretches 52 miles, starting at the Gulf of Mexico and ending just four miles east of downtown.

“We have all these ginormous shipping containers come in on ships from all over the world,” Rosell said. “These containers have water inside them, which can carry mosquitos with different types of viruses and viral loads.”

The team also found that different mosquito species localized to specific parts of the Houston metro area. In the wooded north, Aedes aegypti mosquitos dominate, and Culex quinquefasciatus mosquitos primarily inhabit the south.

In addition to finding viruses with known genomes, the team identified thousands of uncharacterized viral sequences, which they plan to investigate in future studies.

“We are filling in gaps in our understanding of diversity in nature, which ties into health and conservation and affects the human existence,” Larios said. “It’s not just about the ‘sexy’ diseases, but it is also about understanding what kinds of viruses exist in the environment and how they move.”