Even though the first wave of the COVID-19 pandemic has passed its peak in Switzerland, coronavirus diagnostic procedures are as important as ever. For one thing, the continuing aim is to test people who may have become infected so that, if infection is confirmed, they can isolate themselves to prevent the epidemic from flaring up again. For another, it is now time to investigate how many people’s immune systems have produced antibodies in response to the coronavirus in question, SARS-CoV-2 (including in undetected cases of infection). Scientists suspect that once people have contracted the virus, they gain at least temporary immunity to re-infection.
Although experimental research at ETH Zurich has been temporarily suspended, some scientists are working in coordination with the Vice President for Research on the further development of tests that can detect either the pandemic virus itself or antibodies that recognise the virus according to the lock-and-key principle.
Fast and economical virus test
Laboratories worldwide routinely detect the virus itself by way of its genetic fingerprint (RNA sequence). For this they usually employ the PCR method, which can determine whether genetic material from the pandemic pathogen is present in, say, a throat swab. In this method, short sections of viral DNA are replicated in a process of thermal cycling, which exposes the sample to repeated cycles of heating and cooling. The method also requires certain laboratory chemicals that have become scarce worldwide in the current situation.
In recent years, ETH Professor
Wendelin Stark
’s group has developed an improved, cost-effective PCR device that works with tiny metal sample containers rather than the plastic containers that are currently standard. The new device can heat and cool the sample much faster, which speeds up the process considerably. And because the containers are smaller, the scientists needed only one-fifth of the quantity of reagents. Stark and his colleagues have already arranged for their device to go into full-scale production, and they are now planning to apply for official approval. Once this is granted, they can begin marketing the device.
Determining the fingerprint
Meanwhile, ETH Professor
Sai Reddy
and the Genomics Facility at the Department of Biosystems Science and Engineering at ETH Zurich in Basel are employing a different method to detect the virus: deep sequencing. This relatively new method is extremely sensitive – Reddy estimates it to be much more sensitive than PCR – and it can analyse around 5,000 samples at a time. Another great advantage of this technology is that it also provides the exact genetic fingerprint (RNA sequence) of the virus for each sample. Because the pathogen undergoes minute changes over time, this data is ideal for phylogenetic analyses of the virus to determine its family tree.
