mRNA delivery of a class 1/4 SARS-CoV-2 neutralizing antibody protects against diverse sarbecoviruses in a lethal mouse challenge model

A Ashwin N. Skelly C Chengcheng Fan (Division of Biology and Biological Engineering, California Institute of Technology) J Jennifer R. Keeffe (Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.) A Arya B. Ökten (Department of Laboratory Medicine, Yale School of Medicine) E Edem Gavor (Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.) M Maddy L. Newby (School of Biological Sciences, University of Southampton, Southampton, UK.) J Joel D. Allen (School of Biological Sciences, University of Southampton, Southampton, UK.) E Edward F. Kreider W Wenge Ding R Rebecca A. Osbaldeston Y Younghoon Park A Andrew J. Connell M Melinda G. Lituchy F Frederic Bibollet-Ruche K Katelyn M. Radford (Division of Biology and Biological Engineering, California Institute of Technology) A Anthony P. West (Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.) M Mario A. Peña-Hernández (Department of Laboratory Medicine, Yale School of Medicine) K Kendra Cruickshank (Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.) W Weimin Liu Y Yingying Li A Amie Albertus B Brieyanna McWilliams (Department of Medicine, University of Pennsylvania) R Ronnie M. Russell (Department of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania) K Kylie M. Konrath (Biomedical Graduate Studies, Perelman School of Medicine at the University of Pennsylvania) J Jonathan L. Torres (Department of Integrative Structural and Computational Biology, The Scripps Research Institute) M Meng Yuan H Hongmei Gao (Duke Human Vaccine Institute, Duke University Medical Center) D David C. Montefiori (Duke Human Vaccine Institute, Duke University Medical Center) M Michael S. Saag (Department of Medicine, University of Alabama at Birmingham) P Paul A. Goepfert (Department of Medicine, University of Alabama at Birmingham) D Daniel W. Kulp (Department of Biochemistry and Biophysics, The University of Pennsylvania) A Andrew B. Ward I Ian A. Wilson G George M. Shaw R Raiees Andrabi M Max Crispin (School of Biological Sciences, University of Southampton, Southampton, UK.) D Drew Weissman C Craig B. Wilen (Department of Laboratory Medicine, Yale School of Medicine) P Pamela J. Bjorkman (Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.) B Beatrice H. Hahn

Abstract

The unyielding antigenic drift of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as well as the threat of future zoonotic sarbecovirus spillovers, has prompted the search for broadly neutralizing antibodies (bNAbs) to inform rational therapeutic and vaccine design. Here, we isolated and characterized 20 receptor binding domain (RBD)-directed bNAb lineages from a serially sampled SARS-CoV-2 patient who was infected and vaccinated during the early months of the pandemic. Thirteen of these targeted the highly conserved, cryptic class 1/4 or class 4 RBD epitopes and had long (18 to 26 amino acid) heavy chain complementarity determining region 3 loops that utilized the IGHD3-22 gene segment. Five bNAbs potently neutralized all 18 viruses in a panel containing SARS-CoV-2 variants up to the recently emerged XBB.1.5 and JN.1 strains as well as diverse sarbecoviruses from other clades. Structural analyses of the Ab401 and Ab568 bNAbs complexed with RBD and Spike trimer, respectively, revealed recognition features in common with other class 1/4 bNAbs. Prophylactic administration of Ab401 as a recombinant protein afforded robust protection against infectious challenge with either SARS-CoV-2_WA1 or a related bat sarbecovirus with zoonotic potential. A similar level of protection was achieved when the heavy and light chains of Ab401 were delivered as lipid nanoparticle-encapsulated mRNAs. These data expand the arsenal of SARS-CoV-2 bNAbs for clinical development and identify mRNA-based antibody delivery as a promising platform for both pandemic preparedness and protection of immunocompromised patients against emerging sarbecovirus variants.

Article Details

Volume / Issue Vol. 123, Issue 24
Published June 16, 2026
ISSN 0027-8424
Publisher National Academy of Sciences

Authors (40)

A

Ashwin N. Skelly

C

Chengcheng Fan

Division of Biology and Biological Engineering, California Institute of Technology

J

Jennifer R. Keeffe

Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.

A

Arya B. Ökten

Department of Laboratory Medicine, Yale School of Medicine

E

Edem Gavor

Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.

M

Maddy L. Newby

School of Biological Sciences, University of Southampton, Southampton, UK.

J

Joel D. Allen

School of Biological Sciences, University of Southampton, Southampton, UK.

E

Edward F. Kreider

W

Wenge Ding

R

Rebecca A. Osbaldeston

Y

Younghoon Park

A

Andrew J. Connell

M

Melinda G. Lituchy

F

Frederic Bibollet-Ruche

K

Katelyn M. Radford

Division of Biology and Biological Engineering, California Institute of Technology

A

Anthony P. West

Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.

M

Mario A. Peña-Hernández

Department of Laboratory Medicine, Yale School of Medicine

K

Kendra Cruickshank

Departments of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

W

Weimin Liu

Y

Yingying Li

A

Amie Albertus

B

Brieyanna McWilliams

Department of Medicine, University of Pennsylvania

R

Ronnie M. Russell

Department of Medicine and Microbiology, Perelman School of Medicine, University of Pennsylvania

K

Kylie M. Konrath

Biomedical Graduate Studies, Perelman School of Medicine at the University of Pennsylvania

J

Jonathan L. Torres

Department of Integrative Structural and Computational Biology, The Scripps Research Institute

M

Meng Yuan

H

Hongmei Gao

Duke Human Vaccine Institute, Duke University Medical Center

D

David C. Montefiori

Duke Human Vaccine Institute, Duke University Medical Center

M

Michael S. Saag

Department of Medicine, University of Alabama at Birmingham

P

Paul A. Goepfert

Department of Medicine, University of Alabama at Birmingham

D

Daniel W. Kulp

Department of Biochemistry and Biophysics, The University of Pennsylvania

A

Andrew B. Ward

I

Ian A. Wilson

G

George M. Shaw

R

Raiees Andrabi

M

Max Crispin

School of Biological Sciences, University of Southampton, Southampton, UK.

D

Drew Weissman

C

Craig B. Wilen

Department of Laboratory Medicine, Yale School of Medicine

P

Pamela J. Bjorkman

Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.

B

Beatrice H. Hahn