Converting non-neutralizing SARS-CoV-2 antibodies targeting conserved epitopes into broad-spectrum inhibitors through receptor blockade

All but one of the authorized monoclonal antibody-based treatments for SARS-CoV-2 are largely ineffective against Omicron, highlighting the critical need for biologics capable of overcoming SARS-CoV-2 evolution. These mostly ineffective therapeutic antibodies target epitopes that are not highly conserved. Here we describe broad-spectrum SARS-CoV-2 inhibitors developed by tethering the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2), to antibodies that are known to be non-neutralizing, but which target highly conserved epitopes in the viral spike protein. These inhibitors, called Receptor-blocking conserved non-neutralizing Antibodies (ReconnAbs), potently neutralize all SARS-CoV-2 variants of concern (VOC), including Omicron. Neutralization potency is dependent on both the binding and inhibitory ReconnAb components as activity is lost when the linker joining the two is severed. In addition, a bifunctional ReconnAb, made by linking ACE2 to a bispecific antibody targeting two non-overlapping conserved epitopes, defined here, shows sub-nanomolar neutralizing activity against all VOCs, including Omicron. Given their conserved targets and modular nature, ReconnAbs have the potential to act as broad- spectrum therapeutics against SARS-CoV-2 and other emerging pandemic diseases.