A and B Neutralization of SARS-CoV-2 B.1.351/Beta by the indicated VHH antibody constructs. The neutralization experiment was performed as described in Fig 3A, with the difference being that a mutant-optimized anti-RBD/S1 VHH cocktail was used for immunofluorescence staining Two titrations for the Re9F06 trimer are shown, corresponding to the standard (upper row) or a five-fold higher virus inoculum (lower row) that was used for even more stringent neutralization conditions. 