ISOLATION OF PAN-SARBECOVIRUS mABs THAT NEUTRALIZE SARS-CoV-1 AND SARS-CoV-2 VARIANTS

ABSTRACT

Background: The continued emergence of severe acute respiratory syndrome coronaviruses (SARS-CoVs) and recent explosion of the SARS-CoV-2 pandemic highlights the need for broad and potent antibody recognition and understanding the contexts in which they may develop. Antibodies with cross reactivity across SARS lineages may be of particular value in preparing for future outbreaks of new sarbecoviruses. Method(s) We isolated monoclonal antibodies (mAbs) from an individual 60-days post-vaccination, 30-days post Delta-infection. Reconstructed antibodies were screened for binding to a panel of prefusion-stabilized Spike trimers from SARS-CoV-2 and other beta-coronaviruses using enzyme-linked immunosorbent assay (ELISA). Neutralization potency and breadth was assessed using a spike-pseudotyped lentivirus neutralization assay. Additionally, epitope and escape mutant profiling was conducted by deep mutational scanning (DMS) to identify mutations that affect antibody binding. Lastly, binding breadth was further evaluated using a yeast display library of RBDs from SARS-CoV-2 variants and related sarbecoviruses. Result(s) We identified several SARS-CoV-2-specific mAbs that neutralized SARS-CoV-2 variants of concern (VOCs) and SARS-CoV-1. Notably, two of these mAbs (C68.61 and C68.185) neutralized SARS-CoV-1 with an IC50 = 307 and 139 ng/mL (respectively) that is similar to or better than the potency of S309 (IC50 = 206 ng/mL) and CR3022 (IC50 = 981 ng/mL), which are mAbs isolated from individuals with SARS-CoV-1 infections. C68.61 also neutralized all Omicron VOCs tested and retained neutralization activity against currently circulating variants BQ1.1 (IC50=790 ng/ml) and XBB (IC50=590 ng/ml). Key C68.61 mAbescape mutations identified by DMS in the Omicron BA.2 background yeast display library included sites K462, E465, R466, and I468, which are conserved sites across all VOCs and SARS-CoV-1. The isolated mAbs displayed crossreactive binding to RBDs from diverse SARS-CoV-1-related CoVs and African and European sarbecovirus isolates as well as SARS-CoV-2 VOCs. Conclusion(s) Here we describe mAbs from a SARS-CoV-2-infected individual that bound and neutralized both SARS-CoV-2 and SARS-CoV-1, including one that showed breadth across recent VOCs. Given their breadth, these SARS-CoV-2 cross-reactive mAbs may be robust to viral escape and thus could contribute to therapeutic efforts. In addition, these mAbs displayed broad cross-reactive activity across sarbecoviruses and may be beneficial against future spillover events.