"We want to understand how this virus works"

The Swiss Light Source SLS at PSI is still in operation despite the Covid-19 pandemic – and may be urgently needed, especially in these difficult times. Oliver Bunk, head of the Laboratory for Macromolecules and Bioimaging, explains why.
Oliver Bunk, head of the Laboratory for Macromolecules Bioimaging in the hall of the Swiss Light Source SLS. (Photo: Kellenberger Kaminski Photographie/ETH Board)

Mr. Bunk, we are speaking by video call and I can see office shelves behind you, right?

Oliver Bunk: Yes, right now I am in my office at the SLS. Many of the surrounding offices and many of the laboratories are empty. But you could say this emptiness is deceptive. Because work continues at PSI: from home. And yes, something is happening in the laboratories too – just from a distance.

That works?

Yes. For example, on the SLS beamlines for protein structure analysis, we already had the option of carrying out experiments remotely. Then only one person has to be on site to prepare the samples for the robotic gripper arm. Even before coronavirus, about 30 percent of the experiments here were carried out via remote control. When the pandemic emerged, we mounted an impressive effort within a few days to increase this number. And we were successful: Now 100 percent of the experiments for protein structure analysis are actually carried out by remote control.

Since the beginning of the pandemic, PSI has given absolute priority to research on the novel coronavirus, and the first investigations are to begin soon. How can this PSI research help to combat Covid-19?

Here at SLS, we can contribute to understanding how this virus works. How it docks onto the cells of our body, that is, on the cell membrane. And how the virus multiplies. Because if you know that, you can prevent it from functioning and from multiplying. In the end, it will all come down to how drugs can stop the virus from spreading in the body.

What exactly does research on the virus look like?

Think of the virus as a machine made up of many parts. In order to paralyse the virus, you have to understand the individual components – in the case of a virus, these are mainly the proteins.

The coronavirus itself is spherical and around 100 nanometres in size; that means its diameter is one-thousandth of the diameter of a human hair. Its building blocks are correspondingly smaller. With the X-rays from the SLS, we can examine these tiny proteins.

Why the fascination with proteins?

Everywhere in our body, these molecules are on the move. At the SLS, three experimental stations have specialised in the study of proteins for many years. More precisely: to decipher their exact form. We call this structure elucidation or structural analysis.

By the way, the antibodies that our immune system generates in response to the virus are proteins, too. At the moment, however, their exact structure is still unknown.

What is this structure elucidation good for?

On the one hand, it would help enormously in developing a vaccine against the virus.

On the other hand, you need structural analysis to develop drugs that can fight the virus. Because if you know the exact form of a virus protein, you can search for the right active ingredients or assemble them chemically. This procedure is called structure-based drug design. We have a kind of library here at PSI that contains fragments of drug molecules. You can try them out to see which of them can bind to parts of the virus. This is a starting point for developing a drug.

Do we have to worry that PSI researchers could become infected while working on their samples?

No, definitely not. The strength of the SLS lies in two areas: We can use the X-ray radiation from our system to view tissue samples from corona-infected lungs. This could be helpful for diagnostics, and we achieve a much higher image resolution at the SLS than the conventional devices in the hospitals.

Or we can go to even smaller dimensions and take a close look at the proteins of the virus. But you cannot get infected either from the appropriately pre-treated tissue samples or from the proteins, which are only fractions of the virus.

Incidentally, here at the SLS we are only set up for biosafety level 1. We have never performed research on intact viruses here. That is neither our strength nor our concern.

Is the SLS currently doing research only on the coronavirus?

No. We have another concern: Small and medium-sized enterprises – SMEs – have always come to PSI to examine their samples. Or they have sent us their samples and had them examined by our researchers. These are mainly pharmaceutical companies that develop active ingredients. If we didn't process their samples now, yet another part of the economy would fall apart for weeks, along with the restaurants, hairdressing salons, and so on – and the development of vitally important medicines would be delayed. We are helping to prevent this from happening and have explicitly determined not to stop these investigations. On the contrary, we even postponed our usual shutdown over the Easter holidays. And we are getting feedback from SMEs about how happy they are.

How do you find the morale these days among PSI researchers?

In my view, it is very good. It is certainly not easy: People have to comply with the social distancing rules set by the Federal Office of Public Health and should only come to PSI if it is absolutely necessary. Those who come to the laboratory are therefore under a heavy burden and at the same time struggle with loneliness on site. Despite all of this, I find the researchers very committed. I just heard from one of our groups: One researcher performed the experiment here on site and had the support of two colleagues who were virtually present from the home office. That made it possible for this complex experiment to be carried out, which required the experience and expertise of all three. In short: There is still a lot of good teamwork, even at a distance. I find that impressive.

Interview: Paul Scherrer Institute/Laura Hennemann


Dr. Oliver Bunk
Head of the Laboratory for Macromolecules Bioimaging
Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
Telephone: +41 56 310 30 77, e-mail: oliver.bunk@psi.ch [German, English]

Further information

Research on Covid-19