Finally, to test the ability of RBD-PB6 to neutralize infection by real SARS-CoV-2 virus, we performed plaque reduction neutralization tests using replication competent SARS-CoV-2 infection of ACE2- and TMPRRS2-expressing VeroE6 cells in the presence of monomeric, dimeric, or trimeric aptamer. Here, ACE2 is linked to infection.