Open Access

Antonia Sophia Peter, Edith Roth, Sebastian R. Schulz, Kirsten Fraedrich, Tobit Steinmetz, Dominik Damm, Manuela Hauke, Elie Richel, Sandra Müller-Schmucker, Katharina Habenicht, Valentina Eberlein, Leila Issmail, Nadja Uhlig, Simon Dolles, Eva Grüner, David Peterhoff, Sandra Ciesek, Markus Hoffmann, Stefan Pöhlmann, Paul F. McKay, Robin J. Shattock, Roman Wölfel, Eileen Socher, Ralf Wagner, Jutta Eichler, Heinrich Sticht, Wolfgang Schuh, Frank Neipel, Armin Ensser, Dirk Alexander Mielenz, Matthias Tenbusch, Thomas H. Winkler, Thomas Grunwald, Klaus Thomas Überla, Hans-Martin Jäck

• TRIANNI mice carry an entire set of human immunoglobulin V region gene segments and are a powerful tool to rapidly isolate human monoclonal antibodies. After immunizing these mice with DNA encoding the spike protein of SARS-CoV-2 and boosting with spike protein, we identified 29 hybridoma antibodies that reacted with the SARS-CoV-2 spike protein. Nine antibodies neutralize SARS-CoV-2 infection at IC50 values in the subnanomolar range. ELISA-binding studies and DNA sequence analyses revealed one cluster of three clonally related neutralizing antibodies that target the receptor-binding domain and compete with the cellular receptor hACE2. A second cluster of six clonally related neutralizing antibodies bind to the N-terminal domain of the spike protein without competing with the binding of hACE2 or cluster 1 antibodies. SARS-CoV-2 mutants selected for resistance to an antibody from one cluster are still neutralized by an antibody from the other cluster. Antibodies from both clusters markedly reduced viral spread in mice transgenic for human ACE2 and protected the animals from SARS-CoV-2-induced weight loss. The two clusters of potent noncompeting SARS-CoV-2 neutralizing antibodies provide potential candidates for therapy and prophylaxis of COVID-19. The study further supports transgenic animals with a human immunoglobulin gene repertoire as a powerful platform in pandemic preparedness initiatives.