Tracey E. Mullen, Rashed Abdullah, Jacqueline Boucher, Anna Susi Brousseau, Narayan K. Dasuri, Noah T. Ditto, Andrew M. Doucette, Chloe Emery, Justin Gabriel, Brendan Greamo, Ketan S. Patil, Kelly Rothenberger, Justin Stolte and Colby A. Souders

Abstract

Background: Rapid deployment of technologies capable of high-throughput and high-resolution screening is imperative for timely response to viral outbreaks. Risk mitigation in the form of leveraging multiple advanced technologies further increases the likelihood of identifying efficacious treatments in aggressive timelines.

Methods: In this study, we describe two parallel, yet distinct, in vivo approaches for accelerated discovery of antibodies targeting the severe acute respiratory syndrome coronavirus-2 spike protein. Working with human transgenic Alloy-GK mice, we detail a single B-cell discovery workflow to directly interrogate antibodies secreted from plasma cells for binding specificity and ACE2 receptor blocking activity. Additionally, we describe a concurrent accelerated hybridoma-based workflow utilizing a DiversimAb™ mouse model for increased diversity.

Results: The panel of antibodies isolated from both workflows revealed binding to distinct epitopes with both blocking and non-blocking profiles. Sequence analysis of the resulting lead candidates uncovered additional diversity with the opportunity for straightforward engineering and affinity maturation.

Conclusions: By combining in vivo models with advanced integration of screening and selection platforms, lead antibody candidates can be sequenced and fully characterized within one to three months.

KEYWORDS: beacon; single B cell; carterra; epitope binning; neutralizing antibodies; therapeutic; human antibody; COVID

Introduction

The pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), or coronavirus disease 2019 (COVID-19), has received unprecedented attention from the scientific community in an effort to rapidly develop efficacious treatments and vaccines. Within weeks of the emergence of viral pneumonia outbreaks in Wuhan, China, deep sequencing had identified the cause, and the resulting mobilization of widespread therapeutic and prophylactic discovery efforts ensued. The response to the COVID-19 pandemic mirrored that of other recent viral outbreaks, including, but not limited to, H1N1 influenza in 2009, Ebola Virus in 2014 and Zika Virus in 2015. Lessons learned from these public health threats helped guide the strategy for the accelerated response to COVID19. In particular, the understanding that neutralizing antibody function is fundamental to combating disease progression helped streamline early antibody-based drug therapy discovery strategies.

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