Scientists from Heidelberg University in Germany have identified an alternative amplification technique to detect the genetic material of SARS-CoV-2 virus that causes COVID-19. This could offer a way to rapidly test a large number of people for the deadly disease.
However, the researchers noted that the technique is not as sensitive as quantitative RT-PCR, the current standard method for coronavirus testing.
Faster and less complicated testing could help in the rapid isolation of coronavirus positive people and help to identify and prevent new outbreaks of the deadly disease until a vaccine becomes available, they said.
The researchers noted that quantitative RT-PCR can successfully detect viral RNA but requires expensive machinery and chemical reagents that can sometimes be in short supply.
The standard method also depends on time-consuming temperature cycling steps to amplify enough RNA from a patient sample for detection, resulting in a processing time between three and 24 hours in most clinical laboratories, they said.
In the journal Science Translational Medicine, the researchers propose using a technique called reverse transcription loop-mediated isothermal amplification (RT-LAMP), which can be carried out at a constant temperature using simple equipment and a different set of reagents.
In their tests of RNA isolated from 768 nasopharyngeal swabs from individuals tested for Covid-19, the researchers determined that RT-LAMP was less sensitive than quantitative RT-PCR but could be used to evaluate large groups of people, with an average test processing times of 30 minutes.
They concluded that RT-LAMP works best for identifying people with moderate to high amounts of SARS-CoV-2 virus in their bodies, but is not sensitive enough to identify infection in people with a low viral load — such as those at the beginning or end of the illness.
The researchers also tested the possibility of using RT-LAMP directly on nasopharyngeal swabs — without the need for RNA isolation — but concluded this technique was less sensitive than using isolated RNA.
