‘The Bubbler’ reverse-transcribes RNA from airborne SARS-CoV-2, researchers say.
A team of researchers at Brown University and Rhode Island Hospital has developed a unique method for detecting SARS-CoV-2 in breath samples using viral RNA detection.
The researchers created a breathalyzer device that reverse-transcribes RNA from airborne virus particles into DNA, which can then be tested for COVID-19 via a common PCR test. The device, dubbed the Bubbler, uses an enzymatic reaction mixture to detect viral RNA and convert it to DNA, where it can be measured using a PCR instrument. The Bubbler can also barcode that DNA, allowing a sample to be linked directly to the patient it came from and be used for sequencing.
In a new study in the Journal of Molecular Diagnostics, the investigators report on the design and testing of the device. “The Bubbler is more likely to be a better indicator of current infection than nasopharyngeal swabs,” says lead investigator William G. Fairbrother, PhD, a professor of biology.
The Bubbler is a glass tube with a glass pipette into which patients exhale. The tube is filled with a reverse transcription reaction mixture and cold mineral oil. The name of the device comes from the bubbling sound that occurs when the patient exhales into the device.
In the study, 70 patients treated in the emergency department at Rhode Island Hospital between May 2020 and January 2021 were screened. Samples from three points in the respiratory tract were tested: saliva obtained from tongue scrapes in the mouth and samples of 15 seconds of exhaled breath collected in the Bubbler were compared to 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. Viral RNA is more enriched in the breath relative to oral samples, while oral samples include cells involved with SARS-CoV-2 replication that breath samples do not. This suggests the viral signal detected in the Bubbler comes from active viral particles, the authors wrote.