Researchers in the labs of Jennifer Doudna, David Savage, and Patrick Hsu at the University of California, Berkley, is targeting to develop a diagnostic test using an enzyme that's much more rapid and easier to use compared to qRT-PCR, which that most of the time, takes days before a result becomes available.
Now, the team has combined two types of CRISPR enzymes to develop an assay that can determine small amounts of viral RNA in just minutes. Doudna shared the 2020 Nobel Prize in Chemistry for CRISPR-Cas9 genome editing's invention.
A Phys.org report specified that while this new approach hasn't reached the stage yet, where it competes against the qRT-PCR, which has the ability to detect "just a few copies of the virus per microliter of liquid," it can already pick up levels of viral RNA, approximately 30 copies per microliter, adequate to be employed to observe the population and limit transmission of the virus closely.
According to molecular and cell biology professor David Savage, co-author of the study, there is no need for the PCR's sensitivity to basically catch and diagnose the virus in a community if the test is convenient and rapid enough.
Savage added that they hoped to drive the biochemistry as far as possible to the point where one can imagine the extremely convenient format in a setting where he can get himself tested for COVID-19 every day, for example, at the entrance work.
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In the PCR test, the sample is collected using a nasal or throat swab, and it usually takes hours for the results to become available.
Existing COVID-19 Diagnostic Tests
The commonly used diagnostic tests for COVID-19 today are the antigen and PCR tests. Between the two, according to UC Davis Health, antigen tests are less expensive and typically faster. The downside, though, is that they tend to be less precise with the results.
Professor of laboratory medicine and UC Davis Health site principal investigator Nam Tran said there's no need for complex and costly test kits to detect antigens, making these tests more affordable and faster. But the problem is that there's a slight lag time between when an individual gets infected and when the antigens appear.
Next is the polymerase chain reaction or PCR test, which serves as the COVID-19 diagnostic testing's mainstay. Essentially, molecular tests can detect genetic material, the coronavirus's RNA, and they are sensitive enough to need just a small amount on it.
The best PCR tests usually required trained staff, particular reagents, and costly machines to date. The sample is collected using a nasal or throat swab, and it usually takes hours for the results to become available.
CRISPR-Based
Numerous CRISPR-based assays have been authorized by the Food and Drug Administration for emergency use, although all necessitate a first step in which the viral RNA is augmented so that the detection signal, which comprises emission of a fluorescent molecule that develops under blue light, is bright enough for the eyes to see.
Whereas the initial augmentation increases the test's sensitivity to a similar level as qRT-PCR, it also introduces steps, making the test more difficult to perform outside of a lab.
Through their study, Accelerated RNA detection using tandem CRISPR nucleases, published in Nature Chemical Biology, the research team sought to achieve a useful sensitivity and speed minus sacrificing the assay's simplicity.
According to Tina Liu, the team leader and a research scientist in the lab of Doudna at the Innovative Genomics Institute, for applications of point of care, one would want to have a quick response to quickly know if there is a COVID-19 infection or none, before going on a flight, say, to visit a loved one.
CRISPR and COVID-19 are explained on MIT Better World's YouTube video below:
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