1 Institute of Virology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin 10117, Germany; German Centre for Infection Research (DZIF), Berlin 10117, Germany; Labor Berlin-Charité Vivantes GmbH, Berlin 13353, Germany.
2 Institute of Virology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin 10117, Germany; German Centre for Infection Research (DZIF), Berlin 10117, Germany.
3 Department of Molecular and Medical Virology, Ruhr University Bochum, Bochum, Germany; German Centre for Infection Research (DZIF), External Partner Site, Bochum, Germany. Electronic address: eike.steinmann@ruhr-uni-bochum.de.