Abstract
A major challenge during viral pandemics is the ability to develop therapeutics whose efficacy can withstand viral genetic evolution. During the COVID-19 pandemic, five SARS-CoV-2 monoclonal antibody (mAb) therapeutics were rendered ineffective within a period of 2 years, leading to the U.S. FDA revoking their emergency use authorization. Here, we describe ReconnAb-multimers, a new therapeutic design that broadly and potently neutralize all tested betacoronaviruses that use host ACE2 as their receptor to enter cells. These ReconnAb-multimers have potent neutralization efficacy via avidity, enhanced breadth via a new pan-betacoronavirus-binding antibody that targets a highly conserved epitope on SARS-CoV-2 spike protein, and the potential for clinical development by using a catalytically inactive ACE2 component. We demonstrate that ReconnAb-multimers neutralize all SARS-CoV-2 pseudoviruses and authentic viral variants of concern (VOC) tested, with similar or higher potency than mAbs previously approved by the FDA; neutralize related pandemic-potential betacoronaviruses, including SARS-CoV, WIV1-CoV, PRD-0038, and merbecovirus HKU5-CoV-2; and despite a short half-life, protect female mice against authentic viral challenge with Omicron variant XBB.1.5. Our results highlight ReconnAb-multimers as a broad and highly potent therapeutic that could potentially withstand viral escape against current and future betacoronaviruses that require host ACE2 as a receptor.