Washington University researchers to design detectors of airborne SARS-CoV-2 – Washington University School of Medicine in St. Louis
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Alzheimer’s researchers and aerosol engineers are working together to develop rapid screening tools
John Cirrito, PhD, Associate Professor of Neurology at Washington University Medical School in St. Louis, and Carla Yuede, PhD, Associate Professor of Psychiatry, kicked an idea around. Could a biosensor they developed years ago for Alzheimer’s disease be turned into a detector for the virus that causes COVID-19?
The biosensor was designed to measure an Alzheimer’s protein in the brain, but there was no reason it couldn’t be used to detect virus particles in the air instead, they thought. Cirrito and Yuede recruited aerosol expert Rajan Chakrabarty, PhD, an associate professor of energy, environmental, and chemical engineering at the university’s McKelvey School of Engineering, to find a way to quickly search for SARS-CoV-2 in the air, the virus that causes COVID-. 19th
With a $ 900,000 grant from the National Institutes of Health (NIH) National Institute on Alcohol Abuse and Alcoholism, the team now has two devices in the works. One is an aerosol detector designed to continuously monitor air quality in large meeting places such as conference halls, airports and schools. The other is a breathalyzer, which can be used to quickly measure the health of people entering workplaces or other semi-public areas, similar to how heat detectors for fever are already used on the Washington University medical campus.
“Let’s say this aerosol detector goes off in a large crowd,” said Cirrito, the lead investigator for the collaboration. “You could vacate the room right away so people don’t spend a lot of time in a room with someone who is infected and potentially contagious, and mark that room for improved cleaning or disinfection. This could reduce the likelihood of an overarching event. And the breathalyzer – you breathe in, you get a real-time reading when you are clear you are moving on, and when you are not, you are referred for more tests. “
The biosensor was originally developed to detect changes in the levels of the Alzheimer’s protein amyloid beta. To convert the amyloid biosensor into a coronavirus detector, the researchers swapped the antibody that recognizes amyloid for a nanobody – an antibody from llamas – that recognizes a protein from the SARS-CoV-2 virus. The nanobody was developed at NIH in the laboratory of David Brody, MD, PhD, a former faculty member in the Department of Neurology at the School of Medicine.
As soon as the biosensor for the detection of SARS-CoV-2 has been redesigned, it must be tested as an air sensor. But there’s one problem: Not much is known about how the virus-laden droplets – which are spread by coughing, sneezing, or even breathing – move through the air, leaving researchers with no way to validate the readings from the sensor.
“There are many unanswered questions,” said Chakrabarty. Chief among them: What role do environmental conditions and pollution play in transmission?
Fine dust such as soot can travel incredibly long distances. Particles from forest fires in California last year made it to continental Europe. Could virus-laden droplets couple a trip with some soot and cover these huge distances?
And while there are models that suggest how humidity, temperature, pollution, and the like affect droplet size and lifespan, they haven’t been experimentally validated – not to some degree, to be sure that a tiny sensor is in a wagon your own can accurately represent exposure risk.
Chakrabarty’s experiments begin by answering questions about samples of aerosolized droplets of inactivated SARS-CoV-2 provided by the NIH and Jacoo Boon, PhD, an associate professor of medicine. Together with PhD student Esther Monroe, the researchers developed a rotating environmental chamber that resembles an old-school rotating coffee roaster basket. Inside, a virus droplet with a size of a few tens of nanometers to a few micrometers can be suspended, which floats in the chamber for up to several hours. Researchers can adjust certain variables (temperature, humidity and UV exposure) in the chamber to better understand how these aerosolized particles with viruses react to changing conditions and how this affects the detection by the biosensor. Ultimately, they can provide information on how these variables affect a sensor’s ability to detect the particles.
Once they have a better understanding of how SARS-CoV-2-laden droplets are affected by these variables in an artificial laboratory environment, the particulate matter-laden air, also known as PM2.5, comes along. The polluted air is introduced into the rotating environmental chamber for detailed examination with viral droplets.
At this stage, Chakrabarty’s expertise is crucial: in his laboratory, he can produce various PM2.5 pollutants – soot and organics such as those from forest fires in California or from a coal-fired power station. “We want to know what happens when these fine dust particles are found in the ambient air,” he said. “Can the virus survive on their surface and then be inhaled?”
These questions must be answered before a version of the Cirrito biosensor that has been modified to detect SARS-CoV-2 is introduced. A better understanding of the behavior of these aerosol particles will help researchers determine whether the sensor is picking up everything it should – be it on a clear, calm day in a rural setting or in a city plagued by air pollution.
If all goes well the COVID-19 pandemic will end soon, but it is only a matter of time before the next dangerous virus hits the air. The devices could be updated to monitor other threats by replacing the SARS-CoV-2 antibody with one specific to another virus, such as an epidemic strain of influenza or the next coronavirus.
“As long as people gather in groups, contagious respiratory infections will be a problem,” said Cirrito. “I’ve never thought so much about what’s coming out of my mouth as I did last year. Coughing in the supermarket will bring you strange looks for a long time. There are ways to mitigate the hazards, however, and I think devices like this could go a long way in containing the spread of viral diseases like COVID-19 and giving people peace of mind in large crowds. “
The 1,500 faculty physicians at Washington University School of Medicine are also medical staff at Barnes-Jewish and St. Louis Children’s Hospitals. The School of Medicine is a leader in medical research, teaching, and patient care and is consistently one of the best medical schools in the country according to the US News & World Report. The School of Medicine is affiliated with BJC HealthCare through its connections with the Barnes-Jewish and St. Louis Children’s Hospitals.