BERKELEY, Calif. — The demand for testing during the coronavirus pandemic has put a strain on medical centers around the world. As scientists work to simplify the process, a team in California has come up with a way to spot the virus using an ordinary cell phone camera. Using a special device attached to a regular smartphone, researchers say they can accurately test nasal swabs for SARS-CoV-2 — the virus causing COVID-19.
“Our study shows that we can do the detection part of this assay very quickly, making the measurement with mass-produced consumer electronics,” says Daniel Fletcher, a bioengineer at the University of California-Berkeley, in a media release. “We don’t need fancy laboratory equipment.”
Fletcher and study co-author Melanie Ott, a virologist at Gladstone Institutes, collaborated with Nobel laureate Jennifer Doudna for two years on creating a rapid test for HIV that patients could take in their homes. Their focus shifted after seeing the need for more viral load testing during the ongoing pandemic.
Using gene technology to spot SARS-CoV-2
The test utilizes CRISPR-Cas gene sequencing technology. In particular, RNA from a patient sample can be detected by the Cas13 enzyme. Study authors say this is a much simpler process than the current PCR testing technology, which needs to first transcribe the RNA into DNA before analyzing it.
Using this method, Cas13 binds to the RNA of SARS-CoV-2. As it cleaves its way around the sample, researchers added an RNA-based probe to the reaction which produces fluorescence (emits light) that a camera can pick up. The whole procedure takes just 30 minutes to get the results.
“One reason we’re excited about CRISPR-based diagnostics is the potential for quick, accurate results at the point of need,” Doudna explains in a university release. “This is especially helpful in places with limited access to testing or when frequent, rapid testing is needed. It could eliminate a lot of the bottlenecks we’ve seen with COVID-19.”
Making COVID testing easier, using camera phones?
The study focused on testing the detector’s ability to work without needing gene amplification like the standard PCR tests do. For this reason, researchers spiked the nasal swabs with SARS-CoV-2 RNA. The team is now working on a solution that induces the same fluorescence from the virus even without a pure sample of it. Study authors say the fact their device doesn’t need the same amplification means the assay can quantify just how much of the virus is in a sample.
“It’s super exciting to have this quantitative aspect in the assay,” Ott says. “PCR is the gold standard, but you have to go through so many steps. There are huge opportunities here for pathogens and for biology in general to make RNA quantification more precise.”
Believe it or not, the technology in your smartphone is likely better than some of the tools currently helping to detect COVID-19. Researchers say their fluorescence detector uses a laser to create the illumination and lens to collect light. After that, a standard phone is placed on top of the device.
“One takeaway is that the phone camera is ten times better than the plate reader in the lab,” Ott explains. “This is directly translatable to it being a better diagnosis reader.”
An affordable at-home screening kit?
Fletcher and Ott say the goal is to have this test be part of the widescale testing system around the globe; not just for COVID-19 but for viruses like the common cold and flu as well. The team adds they’re hoping to get the cost of the testing cartridges down to around $10. Their final device may not rely on a smartphone at all, but just have a phone camera built right in.
“The eventual goal is to have a personal device, like a mobile phone, that is able to detect a range of different viral infections and quickly determine whether you have a common cold or SARS-Cov-2 or influenza,” Fletcher concludes. “That possibility now exists, and further collaboration between engineers, biologists and clinicians is needed to make that a reality.”
The study appears in the journal Cell.