A Monash University Biomedicine Discovery Institute researcher, Dr Gavin Knott, has developed a CRISPR-based COVID-19 diagnostic test with other international scientists to detect results in 20 minutes, using a smartphone camera.
Current highly sensitive, accurate tests for COVID-19 can take more than two days to produce a result, requiring a person to isolate for that time. What is needed are rapid point-of-care, hand-held tests that have the same accuracy and give a result in less than half an hour. Such a test could be used to check all incoming passengers off a plane and have them cleared as negative before they have exited the airport.
Knott came to Monash University from UC Berkeley 2020 Nobel Laureate Jennifer Doudna’s lab earlier this year. He is a co-author on the paper published in Cell and a recent study published in Nature Chemical Biology, which describes a new Fast Integrated Nuclease Detection In Tandem (FIND-IT) test.
Most COVID-19 diagnostic tests rely on a method called PCR – polymerase chain reaction – which searches for pieces of the SARS-CoV-2 viral RNA in a sample. These PCR tests work by finding the viral RNA, converting the RNA into DNA and then “amplifying” the DNA segments so that the segments can be more easily detected.
As an alternative to PCR, scientists are developing testing strategies based on the gene-editing technology CRISPR, which excels at specifically identifying genetic material.
According to Knott, existing COVID-19 tests use a method called quantitative PCR, but this requires converting the RNA to DNA. The new FIND-IT diagnostic test uses Cas13, a cousin of the genome editor Cas9, that is “programmed” to recognise segments of SARS-CoV-2 viral RNA and, with the help of a protein called Csm6, fluoresce within 15-30 minutes.
These new CRISPR-based tests are emerging as powerful alternatives to conventional diagnostics due to their speed and simplicity.
Due to the complexity of the existing tests, they typically need trained users, specialised reagents and cumbersome lab equipment, which severely limits where testing can occur and causes delays in receiving results. The FIND-IT diagnostic test is a single step that directly detects the viral RNA.
“CRISPR technology offers genuine hope not only for faster COVID testing but for the rapid, cheap and accurate testing of other viral diseases such as influenza and HIV,” Knott said, adding that Mammoth Biosciences, a biotech start-up in California, is working to bring CRISPR-based diagnostics like this to market.
Knott is now researching new ways of detecting and editing RNA.
“Plants, animals and bacteria have spent millions of years evolving elegant ways to make, find or target RNA just to stay alive,” he said.
“We really want to understand how these remarkable systems work so that we can create tools for biotechnology, just like we are doing with CRISPR based diagnostics.”
Read the full paper in Nature Chemical Biology titled “Accelerated RNS detection using tandem CRISPR nucleases.”