‘If they had hired someone else, the virus would never have been noticed so quickly’

‘One day a PhD student came to us with data from sand rockets that had something crazy going on. Sand rockets, aka Arabidopsis thaliana, are small green plants with white flowers, often labeled as weeds. This is the model plant for scientists. What mice are to medicine researchers, thale cress are to plant scientists.

‘She approached us, as a virology department at the University of Wageningen, because she suspected it was a virus. That turned out to be the case, even a virus that had not been noticed before. Shortly after this discovery, I joined another research group in Wageningen for PhD research on a completely different subject, small nematodes in plant roots. Every now and then we still talked about the virus, because little by little more became known.

‘After my PhD at Wageningen University, I found a job at Utrecht University. I started researching the influences of various stressful situations, such as drought, high temperatures and flooding, on the plants. Useful information for farmers who grow crops. But even before my first day at work, they warned me about a strange appearance in the data: in the samples of the thale cress, sometimes more than 90 percent of unknown ‘RNA’ was found. RNA can be seen as the ‘translation step’ between the plant’s DNA and the proteins produced. In our dataset, therefore, the vast majority of the RNA in some samples did not come from the plant. But what was it then?

‘I immediately thought of the earlier problems we encountered in Wageningen. Maybe it was the same new virus? Because I had come across a similar dataset before, I immediately made the link. Indeed it turned out to be so. Very coincidentally, if they had hired someone else, the virus would never have been spotted so quickly. The original research plan faded into the background for a while and I focused mainly on the new discovery.

‘The newly discovered virus is an RNA virus, just like corona, which is why our RNA data sets became so polluted. The virus could go undetected for a long time, because you can’t tell the difference between infected and uninfected plants with the naked eye. I heard from several other researchers that they recognized the problem. But they simply assumed that the dataset was corrupted or failed. Nothing had ever been released about this phenomenon before.

This also became apparent when I posted the find on Twitter. I received several responses from others who recognized the problem. Researchers also came to me after presentations, many researchers had come across the virus at one time or another. For years it had spread worldwide, in labs and in the wild.

‘Generating an RNA dataset costs an enormous amount of money, time and energy. Then you don’t want 90 percent of your well-cared-for plants to actually be a virus, even if the virus seems harmless. That is why a kind of test has now been developed with which you can see whether a plant is infected, comparable to the PCR tests for corona. The research has only just been published, but at my group in Utrecht they are already testing all plants as standard. Hopefully, researchers around the world will soon be checking for this virus.’