Researchers have identified highly effective antibodies against the coronavirus SARS-CoV-2 and are now pursuing the development of a passive vaccination. In this process, they have also discovered that some SARS-CoV-2 antibodies bind to tissue samples from various organs, which could potentially trigger undesired side effects.

Initially, scientists at the German Center for Neurodegenerative Diseases (DZNE Bonn, Germany) and Charité - Universitätsmedizin Berlin (Berlin, Germany) isolated almost 600 different antibodies from the blood of individuals who had overcome COVID-19, the disease triggered by SARS-CoV-2. By means of laboratory tests, they were able to narrow this number down to a few antibodies that were particularly effective at binding to the virus. Next, they produced these antibodies artificially using cell cultures. The identified so-called neutralizing antibodies bind to the virus, as crystallographic analysis reveals, andthusprevent the pathogen from entering cells and reproducing. In addition, virus recognition by antibodies helps immune cells to eliminate the pathogen. Studies in hamsters – which, like humans, are susceptible to infection by SARS-CoV-2 – confirmed the high efficacy of the selected antibodies

“Three of our antibodies are particularly promising for clinical development,” explained Prof. Dr. Harald Prüss, a research group leader at the DZNE and also a senior physician at the Clinic for Neurology with Experimental Neurology at Charité - Universitätsmedizin Berlin. “Using these antibodies, we have started to develop a passive vaccination against SARS-CoV-2.”

In addition to the treatment of patients, preventive protection of healthy individuals who have had contact with infected persons is also a potential application. How long the protection lasts will have to be investigated in clinical studies. During their investigations, the researchers made a further discovery: some of the particularly effective antibodies against the coronavirus specifically attached to proteins of the brain, heart muscle and blood vessels. In tests with tissue samples from mice, several of the neutralizing antibodies exhibited such a cross-reactivity. Thus, they were excluded from the development of a passive vaccination. “These antibodies bind not only to the virus, but also to proteins in the body that have nothing to do with the virus. Future research is needed to analyse whether the associated tissues could potentially become targets of attacks by the own immune system,” said Prof. Prüss. Whether these laboratory findings are relevant for humans cannot be predicted at present. “On the one hand, we need to be vigilant in order to detect any autoimmune reactions that may occur in the context of COVID-19 and vaccinations at an early stage. On the other hand, these findings can contribute to ensure the development of an even safer vaccine,” added Prof. Prüss.

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