Researchers develop an RNA-based breath test to detect SARS-CoV-2.
Transplants to Rhode Island quickly learn that if they’re thirsty, they can sip some water at the bubbler. Now, thanks to researchers at Brown, even the locals are learning a new definition of the word.
The Bubbler is a breathalyzer device that reverse-transcribes RNA from airborne virus particles into DNA, which can then be tested for SARSCoV-2 via a common PCR test.
“The Bubbler is more likely to be a better indicator of current infection than nasopharyngeal swabs,” says lead investigator William G. Fairbrother, PhD, professor of biology.
As the team reported in the Journal of Molecular Diagnostics in December, the Bubbler is a glass tube with a glass pipette into which patients exhale. It’s filled with a reverse transcription reaction mixture and cold mineral oil. They recruited 70 patients to test it, comparing samples from tongue scrapes in the mouth; 15 seconds of exhaled breath collected in the Bubbler; and a conventional nasopharyngeal swab PCR test.
The study determined that SARS-CoV-2 can be readily detected in the breath and is more predictive of lower respiratory tract involvement. Tests for COVID-19 usually use samples collected from the upper respiratory tract by saliva or nasopharyngeal swab. Positive samples contain active virus, but viral load in the upper respiratory tract is not correlated with symptoms in the lower respiratory tract, such as pneumonia.
Furthermore, because swab tests detect viral RNA fragments in cells that persist in previously infected cells, PCR tests can return a positive result for months after infection. By contrast, the Bubbler detects airborne viral particles and is a better measure of risk of contagion, the authors wrote.
The investigators also demonstrated how the Bubbler might be adapted to detect virus in airborne samples, though a detailed exploration of this application was beyond the scope of the study.
“Such technology could be useful in restoring service to industries such as hotels, cruise ships, and casinos,” Fairbrother says. “There is also an epidemiological benefit to routine testing of air at early warning sites such as transportation hubs and hospital emergency departments.”