In the U.S., many states are currently under statewide lockdown or partial lockdown. According to public health experts, in order for the states to safely reopen, millions of people will need to be tested every day. But with the current testing methods that are available—either expensive, self-contained, at-home tests or laboratory tests (like PCR) that require equipment, reagents, and expertise—the country is nowhere near capable of completing so many tests on a daily basis.
Fortunately, Feng Zhang of the Broad Institute in Cambridge, Massachusetts, is developing a solution to this problem. Zhang is one of the pioneers of CRISPR, and he and his colleagues have adapted the technology for use in diagnosing COVID-19. They posted instructions for their new test, called STOPCovid, online for other researchers to see and build upon. However, the study has not yet been peer-reviewed or published by a scientific journal.
CRISPR was introduced several years ago as a precise DNA-editing method. It involves targeting a specific gene locus using guide RNA molecules, which put the Cas9 enzyme in the right location to make a precise cut. Using this technology, scientists can cut out or even replace specific pieces of DNA.
Since its development, CRISPR continues to be adapted in new ways for new purposes. Last year, Zhang’s team developed a CRISPR-based system for viral detection that they called “SHERLOCK”: Specific High-sensitivity Enzymatic Reporter Unlocking. The method involves using guide RNA molecules to bring Cas9 enzymes to the gene of interest, but instead of cutting, the enzymes report its presence via fluorescence and colorimetric readouts.
Building on their SHERLOCK technique, the researchers developed a test to specifically detect SARS-CoV-2. They figured out a way to combine a lot of the reactions into one tube, making the test faster, cheaper, and easier. Additionally, the researchers are now working with manufacturers to design a single cartridge in which the two current steps can take place all at once. The final readout of the test is simple: A piece of paper is placed in the tube, and two lines mean that SARS-CoV-2 is present.
The researchers tested the new technology on 12 patients with COVID-19 and 5 patients without. In 11 of the 12 COVID-19 patients, the new test came out positive in 3 out of 3 tests. In the 12th patient, the new test came out positive in 2 out of 3 tests. In the 5 healthy patients, all tests came back negative.