Researchers based at the University of Toronto have designed a robotic high throughput sequencing platform that can screen thousands of patient samples at once for infection with SARS-CoV-2 to a high degree of accuracy.
The gold standard for SARS-CoV-2 infection testing is RT-PCR, due to its high accuracy. However, this technique has a number of drawbacks, primarily that it is time consuming, hard to scale and relatively expensive compared with other methods.
The pandemic is now so widespread that even with several vaccines now being rolled out, rapid testing methods that can screen many thousands of people are essential for us to have some hope of getting back to normal life.
The Canadian team, led by professor Jeff Wrana, Ph.D., and senior investigator Laurence Pelletier, Ph.D., both based at the Lunenfeld-Tanenbaum Research Institute linked to the University, wanted to develop a testing method that could be quick and accurate, but also have the ability to scan thousands of samples at the same time.
The robot-driven platform allows small sections of the virus to be sequenced quickly and in conjunction with other samples. As reported in the journal Nature Communications, the team tested several hundred samples on the platform and achieved a specificity (ability to detect if people are not infected) of 100% and a sensitivity (ability to tell if people are infected) that varied from 91% in samples with low viral loads to more than 95% in those with higher viral loads.
Notably, the researchers added a step to the process that allows the test to search for different variants of the virus, something that could be very useful with specific mutations becoming more of an issue in recent months.
“Identifying positive samples quickly and accurately is critical in beating this pandemic,” said Wrana. “With new and potentially dangerous variants now circulating, this is a platform that is scalable, automated and capable of analyzing thousands of COVID-19 patient samples in a single instrument run.”
The new testing platform has been developed within 12 months due to multiple collaborations at the university. Another useful factor, compared with other tests, is that it is fairly cheap to run with each sample costing around $8 to run, largely because so many samples can be run at the same time.
So far, large scale, high throughput COVID-19 testing has been fairly limited. It is hard to achieve with PCR and although it is possible with antigen tests, researchers and developers have not yet taken on the challenge of scaling up these tests. RT-LAMP – which is similar to PCR but quicker and simpler, albeit not as accurate – has been successfully scaled up by researchers and companies for rapid SARS-CoV-2 testing at scale.
For example, California-based Color, a company with a focus on population genomics and sequencing, set this up last year and is currently working with local government to roll out large scale, rapid throughput testing in the area.
