Dallas researchers have developed a new test based on eight regions of the viral genome that can be easily updated. Effects of variable control and selection of monoclonal therapies in high-risk patients
Researchers at UT Southwestern Medical Center in Dallas announced that they have created a test, CoVarScanis not only able to detect positivity towards Covid but also Define the variable.
Using this test, we can Define existing variables very quickly In society, and if a new variable appears, explain Jeffrey Sorrell professor of pathology and senior author of the study published in the journal Clinical Chemistry.
According to researchers, the test can be beneficial To monitor the spread of variables and make clinical decisions quickly, especially for monoclonal selection. The test may be particularly useful for individual patients when we are dealing with variables that respond differently to treatments, the researcher adds.
Pierangelo ClericiThe president of the Italian Society of Clinical Microbiologists emphasized the epidemiological importance of the new test: knowing the spread of variants quickly is useful if the numbers matter, as now; Less if the numbers go down. We also don’t know the cost of the device, so we can’t currently assess whether the cost and benefits will be real.
There will not be much differences in the choice of treatments at the moment. Today, the same antiviral drugs are used to combat Covid-19 regardless of the variables. Monoclonal is an exception, and we’ve seen it work differently depending on the strain. However, if personalized treatments become available in the future depending on the variables, the test could be very useful.
How it works
There are many other tests for Covid-19, but they usually do not provide information to identify the variant. To understand this, scientists have to turn to Whole genome sequencingIt is a long and expensive process that takes a few days.
CoVarScan focuses on Eight regions of the genome for Sars-CoV-2 that differs between viral variants. It detects small mutations – in which the sequence of blocks of RNA varies – and measures the length of certain genetic regions that tend to grow or contract as the virus evolves. The method relies on polymerase chain reaction (PCR), a common technique in most pathology laboratories, to transcribe and quantify RNA at these eight sites of interest.
To check the effectiveness of CoVarScan SoRelle, conducted Tests on more than 4,000 positive nasal swab samples to Covid-19 collected between April 2021 and February 2022. The tests were validated using whole genome sequencing, the reference standard and clinicians used the results to select treatments for some critically ill Covid-19 patients.
Compared to whole-genome sequencing, CoVarScan had a sensitivity of 96% and a specificity of 99%. CoVarScan has identified and marked Delta, Mu, Lambda and Omicron variantsincluding version Bachelor 2 by Omicron.
But can the new test be easily updated? SoRelle responds to a common criticism that this type of test requires constant tweaking of new variables, but CoVarScan hasn’t needed any tweaks in over a year and continues to perform very well. Meanwhile, BA.2, Omicron 4 and 5 also appeared and in India a new sub-variable was identified: BA.2.75 which appears to be more contagious.
In the future, if we need to fix it, we can easily add another 20 or 30 hotspots (points in the genome that are sensitive to virus evolution) for testing. Another limitation is that the test appears to be highly sensitive. In 95% of the cases tested – explains Pierangelo Clerici – the intercepted viral load was high and of infectious value, but in a significant percentage, the test also identified smears with a very low viral load, which are considered non-infectious, as positive. Individuals who cannot become infected will also be positive.
Jul 7, 2022 (changed Jul 7, 2022 | 15:44)
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