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The corona pandemic is still raging around the globe. And it is still causing record numbers of infections and disease-related deaths on a daily basis. At the same time, there are new glimmers of hope almost every day that this state of emergency will come to an end in the foreseeable future. The development of vaccines is making leaps and bounds. Biontech/Pfizer, Moderna, and now also AstraZeneca are close to obtaining approval for their products. But there is also a constant stream of new insights when it comes to drugs for treating COVID-19, the disease caused by the coronavirus.

Scientists at the Goethe-Universität Frankfurt am Main in Germany, the University of Kent (UK), and the Medizinische Hochschule Hannover (Germany) have now discovered that the protease inhibitor aprotinin can prevent cells from becoming infected. In the past, aprotinin was used to treat post-operative bleeding. Nowadays, doctors in Russia use it to treat influenza.

Spikes become inactive

The SARS-CoV-2 virus is covered in spike proteins on its surface. It uses these spikes to dock to proteins (ACE2 receptors) on the surface of host cells. However, before this can be done, parts of the spike protein must be separated by the enzymes of the host cells – proteases.

Under the supervision of Prof. Jindrich Cinatl, Institute of Medical Virology at Frankfurt University Hospital, and Prof. Martin Michaelis and Dr. Mark Wess (both from the University of Kent), researchers have now been able to demonstrate in experiments with different cell cultures that aprotinin can stop virus replication in the cells. The scientists explain that since SARS-CoV-2 reduces the formation of protease inhibitors by the host cells after infection, aprotinin is apparently able to compensate for this. The virus can no longer penetrate the host cells.

“Our findings show that aprotinin is effective against SARS-CoV2 in concentrations that can be achieved in patients,“ Professor Jindrich Cinatl “In aprotinin we have a drug candidate for the treatment of COVID-19 that is already approved for other indications and could readily be tested in patients.”

In Russia, aprotinin aerosols for the treatment of influenza have already been approved, given that these types of influenza viruses also need host cell proteases in order to penetrate cells.