For a quick COVID-19 test, iSCAN can be adopted for airports and public transport

A simple COVID-19 test kit combines virus amplification with a CRISPR-Cas system for effective detection of SARS-CoV-2. The kit, called iSCAN, uses reagents that can be produced locally.

“Our entire iSCAN procedure can be completed in under an hour and can easily be adopted as a point-of-care detection system at airports and borders,” says KAUST Ph.D. student Ahmed Mahas.

The current gold standard in SARS-CoV-2 testing is the PCR test, in which DNA primers recognize specific RNA sequences in the viral genome which are then copied using a specific enzyme. This “amplification” process makes it easier to detect the originally small amounts of viral RNA present in nasopharyngeal swabs taken from patients. This test can reliably detect whether a person really has the virus without giving too many false positive or negative results. But it needs highly trained personnel to conduct the test, which is done in stages in central laboratories with sophisticated equipment.

iSCAN, developed by a team led by KAUST bioengineer Magdy Mahfouz, overcomes many of the drawbacks of the PCR test by providing relatively reliable results.

It is significant that the test reagents were manufactured by KAUST. This includes the enzymes needed for amplification and another enzyme that specifically detects viral sequences within the copied material. The availability of reagents and equipment has been a huge obstacle since the start of the COVID-19 pandemic.

To use iSCAN, the contents of a patient’s sample, collected with a nasopharyngeal swab, are placed in a small tube containing the DNA primers and enzymes that can amplify the SARS-CoV-2 genetic material. The contents are incubated at a temperature of 62 degrees Celsius for half an hour. This process is called RT-LAMP. Once enough viral RNA is amplified, a drop containing the Cas12 enzyme is added to the mixture and left for another 15 minutes. This enzyme recognizes only viral RNA belonging to SARS-CoV-2, overcoming a problem with RT-LAMP, where false amplification and cross-contamination can be a problem.

Finally, one of the two methods can be used to view the result. One is to make ultraviolet light shine on the sample, with a detector that analyzes the light that comes out of it to report the amount of viral RNA. The other approach involves inserting specially designed strips into the tubes, similar to those used in pregnancy tests. Both approaches work well, although the ultraviolet light method provided more accurate results.

The scientists tested their kit on synthesized viral RNA and real patient samples. “We are now improving and simplifying our system for users in order to commercialize our iSCAN detection kit,” says researcher KAUST Zahir Ali.