- A new coronavirus test needs only five minutes to deliver a positive diagnosis and has another advantage compared to traditional testing — it can also determine the viral load of an individual.
- The CRISPR test was developed by a USCF team led by Jennifer Doudna, the scientist who won a share of this year’s Nobel Prize in Chemistry for her role in discovering CRISPR.
Coronavirus testing has been a significant problem during the first months of the US epidemic, preventing health officials from testing asymptomatic people who might have been unknowingly spreading the disease. Diagnosing and isolating infected patients as fast as possible is a key for containing the spread of the illness, and other countries have shown how effective extensive testing can be. Germany is one example that stands out thanks to its testing protocols employed during the country’s first COVID-19 wave. Germany detected hundreds of thousands of infected people very early on, which allowed it to contain the transmission and potentially save lives. The earlier a COVID-19 diagnosis can be established, the earlier a patient can be monitored and treated, especially in at-risk groups.
COVID-19 testing got much better, but results can still be delayed. And even the fastest available PCR tests aren’t always fast enough. That’s why researchers have come up with a sophisticated coronavirus test that delivers results in just five minutes. And unlike PCR tests, the test can also provide information about an infected individual’s viral load.
Researchers at UC San Francisco led by Melanie Ott and Jennifer Doudna have come up with a CRISPR coronavirus test that might be a game-changer. Doudna happens to be the chemist who won a share of this year’s Nobel Prize in Chemistry for her role in the discovery of CRISPR.
The diagnostic test that the UCSF team devised does not require expensive lab equipment and can be deployed in places that wouldn’t normally support COVID-19 testing. Schools, office buildings, airports, and doctor’s offices could all support these fast tests that provide results almost instantly.
“It looks like they have a really rock-solid test,” University of California molecular biologist Max Wilson told ScienceMag. “It’s really quite elegant.”
What the UCSF scientists did was to identify an RNA sequence of the SARS-CoV-2 virus that’s just 20 RNA bases long. They then created a “guide” RNA that complements the viral sequence and will bind to it in a solution. When the binding occurs, a “scissor” enzyme cuts any nearby RNA, and these cuts release a fluorescent particle in the solution that’s tested. A laser light then hits the solution and the fluorescent particles would light up in the event of a positive diagnosis.
The idea of using CRISPR tests for COVID-19 isn’t new, but the UCSF team developed a new technique that doesn’t have to amplify the RNA coronavirus before a test is done. The scientists say the test can detect as few as 100,000 virus particles per microliter of solution. Adding a second guide would let them detect as few as 100 per microliter.
Comparatively, PCR tests can detect just one virus per microliter, but PCR tests amplify the viral genetic material during the test. Even so, Ott told ScienceMag that the new test was able to accurately identify a batch of five positive clinical samples in just five minutes per test. A standard PCR test would need a day for a diagnosis.
Because it doesn’t amplify the genetic material, the UCSF 5-minute COVID-19 test has an added benefit. It can quantify the amount of virus in the sample and determine an individual’s viral load. This additional piece of information could help doctors decide how to treat a patient, and it also might prove useful in studies looking at patients’ infectivity.
Fast, accurate COVID-19 tests like this one could be used to speed up tests inside communities grappling with outbreaks and could help with contact tracing efforts as well. The scientists have published their research in medRxiv, which means it hasn’t yet been peer-reviewed. The team is looking to validate its test and find ways to commercialize it. For the time being, it’s unclear when the UCSF CRISPR test will be available or how much it would cost.