New COVID-19 RNA test can give accurate results within minutes

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In a new study, researchers invented a COVID-19 test that reduces testing time from 30 minutes to under five and delivers accurate results.

They also demonstrated the rapidity and sensitivity of their method using patient sample RNA provided by Public Health England.

The research was conducted by a team at the University of Birmingham.

The current gold standard is the Reverse Transcription Polymerase Chain Reaction (RT-PCR) test. This takes more than an hour per sample and has two steps.

The first, which takes 30 minutes, uses a reverse transcriptase enzyme to convert RNA to DNA.

The second uses a DNA polymerase enzyme to copy the DNA and amplify it to detectable levels and requires time-consuming cycles of heating and cooling.

Although single temperature processes have been developed this year, reducing this step below 20 minutes has proved challenging.

Lateral flow tests, which measure the presence of antibodies, can take up to 30 minutes.

In the study, the team created a novel single-step approach for converting viral RNA into DNA and combined it with a known technique called Exponential Amplification Reaction (EXPAR), which increases DNA concentration to detectable levels at a constant temperature.

They are calling the new method Reverse Transcriptase Free EXPAR (RTF-EXPAR) testing.

The method uses a DNA sequence (called Binder DNA) that recognizes and binds to SARS-CoV-2 viral RNA and an enzyme (BstNI) that recognizes the Binder DNA and cuts a short section from it when viral RNA is present.

Once this cleavage has occurred, the viral RNA is free to bind to more Binder DNA and the cycle is repeated. The test detects the output of this cycle.

The method was developed to reduce time and increase throughput in COVID-19 testing.

The University of Birmingham Enterprise has filed a patent application covering the method and its use in diagnostic equipment and is now seeking to license the patent for rapid product development.

One author of the study is Professor Tim Dafforn.

The study is published in MedRxiv.

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