Enhanced fitness of SARS-CoV-2 variant of concern Alpha but not Beta
Lorenz Ulrich, Nico Joël Halwe, Adriano Taddeo, Nadine Ebert, Jacob Schön, Christelle Devisme, Bettina Salome Trüeb, Bernd Hoffmann, Manon Wider, Xiaoyu Fan, Meriem Bekliz, Manel Essaidi-Laziosi, Marie Luisa Schmidt, Daniela Niemeyer, Victor M. Corman, Anna Kraft, Aurélie Godel, Laura Laloli, Jenna N. Kelly, Brenda M. Calderon, Angele Breithaupt, Claudia Wylezich, Inês Berenguer Veiga, Mitra Gultom, Sarah Osman, Bin Zhou, Kenneth Adea, Benjamin Meyer, Christiane S. Eberhardt, Lisa Thomann, Monika Gsell, Fabien Labroussaa, Joerg Jores, Artur Summerfield, Christian Drosten, Isabella Eckerle, David E. Wentworth, Ronald Dijkman, Donata Hoffmann, Volker Thiel, Martin Beer, Charaf Benarafa
Abstract
Abstract Emerging variants of concern (VOCs) are driving the COVID-19 pandemic 1,2 . Experimental assessments of replication and transmission of major VOCs and progenitors are needed to understand the mechanisms of replication and transmission of VOCs 3 . Here we show that the spike protein (S) from Alpha (also known as B.1.1.7) and Beta (B.1.351) VOCs had a greater affinity towards the human angiotensin-converting enzyme 2 (ACE2) receptor than that of the progenitor variant S(D614G) in vitro. Progenitor variant virus expressing S(D614G) (wt-S 614G ) and the Alpha variant showed similar replication kinetics in human nasal airway epithelial cultures, whereas the Beta variant was outcompeted by both. In vivo, competition experiments showed a clear fitness advantage of Alpha over wt-S 614G in ferrets and two mouse models—the substitutions in S were major drivers of the fitness advantage. In hamsters, which support high viral replication levels, Alpha and wt-S 614G showed similar fitness. By contrast, Beta was outcompeted by Alpha and wt-S 614G in hamsters and in mice expressing human ACE2. Our study highlights the importance of using multiple models to characterize fitness of VOCs and demonstrates that Alpha is adapted for replication in the upper respiratory tract and shows enhanced transmission in vivo in restrictive models, whereas Beta does not overcome Alpha or wt-S 614G in naive animals.