Midlands researchers unveil faster, simpler, more sensitive Covid-19 test

Researchers from the University of Birmingham have confirmed the speed, accuracy and simplicity of a novel, highly sensitive testing method for COVID-19 that can be deployed at entertainment venues, airport arrival terminals, and in remote settings where clinical testing laboratories are not available.

The scientists used a three-way comparison study to confirm that the Exponential Amplification Reaction (EXPAR) method is just as sensitive, but faster, than both PCR and LAMP tests which are currently used in hospital settings.

The Birmingham COVID-19 test, called RTF-EXPAR, gives a sample-to-signal time of under ten minutes, even for low viral levels where current lateral flow tests are less effective.
Both PCR and LAMP tests detect viral RNA, which can be present in extremely low levels in swabs taken from the mouth and nose.

These tests use a two-step process that involves first converting RNA to DNA (a process called reverse transcription) and then ‘amplifying’ the material many times over so it can be detected in the sample.

One of the researchers Professor Tim Dafforn said:

Both the reverse transcription and amplification steps slow down existing COVID assays that are based on nucleic acid detection, compared to antigen tests, such as lateral flow, which do not have these steps.

However, while this makes lateral flow tests faster than those based on PCR and LAMP, in return they are typically less sensitive.

An ideal test would be one that is both sufficiently sensitive and speedy – our test, called RTF-EXPAR, achieves this goal.

RTF-EXPAR achieves this feat in two ways – firstly the assay team designed a new RNA-to-DNA conversion step that avoids reverse transcription, making it reverse transcription-free (RTF).

Secondly, their amplification step to generate the read-out signal uses EXPAR, an alternative DNA amplification process to PCR and LAMP.

The study revealed that the RTF-EXPAR method converts under ten strands of RNA into billions of copies of DNA in under ten minutes, using a one-pot assay that is compatible with more basic, benchtop equipment than that used with current testing methods.

RTF-EXPAR also demonstrated significant improvements over both PCR and LAMP-based assays on time to signal detection.

The RTF-EXPAR method can be quickly adapted to recognise new variants, or for testing other viral pathogens such as Influenza, Respiratory Syncytial Virus (RSV), or Ebola, where near-patient testing is required to prevent more widespread transmission.

The team is now seeking commercial partners for rapid licensing, to make the RTF-EXPAR test as available as widely as possible.

For the latest on our region, subscribe to Midlands Matters, the official newsletter of the Midlands Engine.