Delivering dust: Researchers use dust to track COVID-19 in buildings

The Lantern
Nicole Renninger, PhD student in engineering and graduate researcher in The Indoor Environmental Quality Laboratory, performs a step in the RNA extraction process. Credit: Courtesy of Kevin Satterfield

Students deliver all the time, whether it be at part-time jobs making pizzas, running on fumes during finals week to earn a good grade or driving the energy in the Ohio Stadium with 100,000 other fans on Saturdays.

Once the dust settles, Josh Blankenship transports a different delivery.

Blankenship, a third-year in biological engineering and an undergraduate researcher in the Indoor Environmental Quality Laboratory at Ohio State, delivers vacuum bags of dust from custodial staff to the Applied Microbiology Services Laboratory between classes. Researchers are extracting RNA from these samples to identify COVID-19 variants and trace virus pockets in campus buildings this fall.

Once dust is collected from a building and transported to the lab, it is sieved to achieve an even mixture, Karen Dannemiller, an assistant professor of civil, environmental and geodetic engineering and director of the Indoor Environmental Quality Laboratory, said. Researchers then extract RNA and run it through an Illumina sequencing system — a machine used to order genomic DNA and RNA —  to determine the presence and concentration of COVID-19 variants.

Dannemiller said the laboratory previously focused on fungal functions and the microbiome before the pandemic, but her team wanted to help fight COVID-19 by surveying virus prevalence in different buildings.

“We wanted to try to develop something that could be used for monitoring of COVID-19 at the building scale,” Dannemiller said. “Individual testing gives you really great, high-resolution data about exactly who might potentially be infected at any given time, but it is also expensive and cumbersome. We wanted sort of a mid-resolution option that you could use at the building scale to continue to monitor for COVID-19.”

Dannemiller said collected dust can’t identify individual infections or specific areas of the building where the virus is prevalent, just that it was once present in that environment.

The team collects air samples, surface swabs and bulk dust samples for the lab. Dannemiller said recently collected air samples were 20 to 30 percent positive, surface swabs were 55 percent positive and bulk dust samples from vacuum bags were 89 percent positive.

Dannemiller said samples are collected once a week in all residence halls and multiple public buildings on campus, assembled along custodial staffs’ typical cleaning routines.

She said she previously conducted a study showing the infectious outer envelope of the virus degrades rapidly in the environment. But in dust, the virus’ non-infectious RNA remnants can linger for up to thirty days.

“You have the envelope on the outside of a capsule, and then the RNA in the middle. We’re measuring that RNA, so we’re basically measuring a leftover viral fragment,” Dannemiller said. “The outer viral envelope is necessary to cause infection.”

Blankenship said he transports samples by bike, making several trips to the lab at a time.

“It’s anywhere from three to seven bags on a run, kind of just depending on where I’m picking up from,” Blankenship said. “Each vacuum bag is separated into its own Ziploc bag that keeps from cross contaminating, but right now I’m pretty much transporting all of it in my backpack.”

The lab’s RNA extraction technique has proven useful in studying COVID-19, and Dannemiller said it could come in handy for advanced viruses in the future.

“This is really just one tool in the toolbox that we can use to fight against COVID-19,” Dannemiller said. “It can be integrated with all of the other tools we have on campus that are used to keep people safe. It’s really complimentary to the individual testing and wastewater monitoring that’s happening. This technique has potential future-wide applicability to a lot of situations where you want to conduct monitoring for a respiratory virus.”

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