Joining a function-enhanced Fc-portion of human IgG to the SARS-CoV-2 entry receptor ACE2 produces an antiviral decoy with strain transcending virus neutralizing activity. SARS-CoV-2 neutralization and Fc-effector functions of ACE2-Fc decoy proteins, formatted with or without the ACE2 collectrin domain, were optimized by Fc-modification. The different Fc-modifications resulted in distinct effects on neutralization and effector functions. H429Y, a point mutation outside the binding sites for FcγRs or complement caused non-covalent oligomerization of the ACE2-Fc decoy proteins, abrogated FcγR interaction and enhanced SARS-CoV-2 neutralization. Another Fc mutation, H429F did not improve virus neutralization but resulted in increased C5b-C9 fixation and transformed ACE2-Fc to a potent mediator of complement-dependent cytotoxicity (CDC) against SARS-CoV-2 spike (S) expressing cells. Furthermore, modification of the Fc-glycan enhanced cell activation via FcγRIIIa. These different immune profiles demonstrate the capacity of Fc-based agents to be engineered to optimize different mechanisms of protection for SARS-CoV-2 and potentially other viral pathogens.
Keywords: ACE2-Fc; ADCC; COVID-19; SARS-CoV-2; antibody effector function; complement; coronavirus; neutralization.
Copyright © 2022 Wines, Kurtovic, Trist, Esparon, Lopez, Chappin, Chan, Mordant, Lee, Gherardin, Patel, Hartley, Pymm, Cooney, Beeson, Godfrey, Burrell, van Zelm, Wheatley, Chung, Tham, Subbarao, Kent and Hogarth.