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A new method developed by the NIH bypasses genetic RNA extraction, simplifying the testing process.
Scientists at the National Institutes of Health (NIH) have developed a new sample preparation method to detect SARS-Cov-2. Because this method bypasses extraction of the virus’ genetic RNA material, it simplifies sample purification and may reduce test time and costs.
Standard COVID-19 tests amplify viral RNA to detectable levels using quantitative reverse transcription polymerase chain reaction (RT-qPCR). RNA must be extracted from the sample to use this technique, which has put strain on manufacturers of RNA extraction kits.
NIH researchers tested a chelating agent (Chelex 100) made by lab supply company Bio-Rad to determine if it could be used to circumvent the traditional testing process. This agent preserves SARS-CoV-2 RNA in samples for detection through RT-qPCR.
Standard samples were tested using conventional RNA extraction and RT-qPCR, while those stored in the chelating agent were heated and then tested by RT-qPCR. NIH found that the new preparation method significantly increased the RNA yield available for testing relative to the standard method.
“We used nasopharyngeal and saliva samples with various virion concentrations to evaluate whether they could be used for direct RNA detection,” said Bin Guan, a fellow at the National Eye Institute's Ophthalmic Genomic Laboratory, in a press release from the organization. “The answer was yes, with markedly high sensitivity. Also, this preparation inactivated the virus, making it safer for lab personnel to handle positive samples.”