American molecular biologists have created a new test system based on the genomic editor CRISPR/Cas 12 for detecting traces of a new type of coronavirus. According to scientists, it does not give false-positive results. Description of the development was published in the scientific journal Nature Biotechnology.
“We created a quick and easy-to-use test by adapting CRISPR/Cas12 to search for fragments of viral RNA in smears from the respiratory tract of patients. Our method is more visual and works faster than the PCR (polymerase chain reaction) systems used by the US Centers for disease control and prevention. It correctly identifies 95% of positive and 100% of negative cases”, the scientists write.
In recent months, scientists have created several versions of test systems that detect traces of the new coronavirus in a patient’s blood samples or secretions. As a rule, they are based either on the detection of fragments of RNA of the pathogen COVID-19 using polymerase chain reaction (PCR) and its analogs or on the detection of antibodies to a new type of coronavirus.
Initially, the accuracy of both tests was extremely low, and the speed of their implementation was quite low. In recent weeks and months, their quality has improved enough to conduct extensive epidemiological studies in a large number of coronavirus carriers.
Specialists from the University of California at San Francisco (USA), as well as their colleagues from the California Department of public health, have developed an alternative to both methods. In their work, they used the genomic editor CRISPR/Cas12, which many bacteria use as a kind of “antivirus”.
In contrast to the more popular and well – known “brother” of this system — CRISPR/Cas9 – it requires a little more effort to use it. However, it is much more accurate to recognize editable sections of DNA and allows you to “cut” accurately them from the thread of the genetic code.
The authors of the article used this feature of CRISPR/Cas12 to make the search for the SARS-CoV-2 virus in the samples of the patient’s biological fluids much more accurate. To do this, scientists have prepared a set of RNA tags that can “stick” to specific sites in two key genes of the coronavirus. If this happens, the CRISPR/Cas12 system attaches to them and cuts the labels, after which they start to glow. This allows you to detect the presence of the virus even with the naked eye.
Thanks to this, the researchers note, it is possible not only to find traces of SARS-CoV-2 very accurately in the sample or to determine their absence but also to distinguish fragments of the coronavirus and its close relatives, the pathogen of SARS and middle East mers fever, as well as other coronaviruses.
The main advantage of this approach, according to its creators, is not only its high accuracy but also that it does not need expensive equipment and specialized reagents. The researchers hope that their CRISPR / Cas12 test will soon be approved for clinical use and will help doctors more accurately track the spread of the virus.