An infectivity-enhancing site on the SARS-CoV-2 spike protein targeted by antibodies

“Discussion: Antibody-dependent enhancement (ADE) of viral infection has been reported for some viruses such as dengue virus (Wan et al., 2020), feline infectious peritonitis virus (FIPV) (Hohdatsu et al., 1998; Vennema et al., 1990), severe acute respiratory syndrome coronavirus (SARS) (Jaume et al., 2011; Kam et al., 2007), and Middle East respiratory syndrome (MERS) (Wan et al., 2020). Binding of the Fc receptor to anti-virus antibodies complexed with virions has been thought to be involved in ADE (Wang et al., 2017). However, Fc-receptor-mediated ADE is restricted to the infection of Fc-receptor-expressing cells such as monocytes or macrophages. In this study, we found a non-canonical, Fc-receptor-independent ADE mechanism. The antibodies against a specific site on the NTD of the SARS-CoV-2 spike protein were found to directly augment the binding of ACE2 to the spike protein, consequently increasing SARS-CoV-2 infectivity.”