Mycophenolic acid treatment drives the emergence of novel SARS-CoV-2 variants

T Toni Luise Meister (Department for Molecular and Medical Virology, Ruhr University Bochum) M Maximilian K. Nocke (Department for Molecular and Medical Virology, Ruhr University Bochum) N Natalie Heinen (Department for Molecular and Medical Virology, Ruhr University Bochum) T Thomas L. Burkard (Department for Molecular and Medical Virology, Ruhr University Bochum) Y Yannick Brüggemann (Department for Molecular and Medical Virology, Ruhr University Bochum) S Saskia Westhoven (Department for Molecular and Medical Virology, Ruhr University Bochum) B Bettina Trüeb (Institute of Virology and Immunology, Bern and Mittelhäusern) N Nadine Ebert (Institute of Virology and Immunology, Bern and Mittelhäusern) L Lisa Thomann (Institute of Virology and Immunology, Bern and Mittelhäusern) K Krzysztof P. Lubieniecki (Department of Human Genetics, Ruhr University Bochum) J Joanna M. Lubieniecka (Department of Human Genetics, Ruhr University Bochum) K Kristina Döring M Maike Herrmann (Section VET5 - Veterinary Medicine Research, Paul Ehrlich Institute) S Sibylle Haid (TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture between Helmholtz-Centre for Infection Research and Hannover Medical School) T Thomas Pietschmann (TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture between Helmholtz-Centre for Infection Research and Hannover Medical School) B Bettina Wiegmann (Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School) R Ronny Tao (Institute of Virology, Medical Faculty, Heinrich-Heine-University) S Susanne Pfefferle (Institute of Medical Microbiology, Virology and Hygiene, Centre for Diagnostics, University Medical Centre Hamburg-Eppendorf) M Marylyn M. Addo (Institute for Infection Research and Vaccine Development, Centre for Internal Medicine, University Medical Centre Hamburg-Eppendorf) V Volker Thiel (Institute of Virology and Immunology, Bern and Mittelhäusern) I Ingo Drexler (Institute of Virology, Medical Faculty, Heinrich-Heine-University) N Nina Babel (Medical Department I, Centre for Translational Medicine and Immune Diagnostics Laboratory, Marien Hospital Herne, University Hospital of the Ruhr-University Bochum) H Huu Phuc Nguyen (Department of Human Genetics, Ruhr University Bochum) R Richard J. P. Brown (Department for Molecular and Medical Virology, Ruhr University Bochum) D Daniel Todt (Department for Molecular and Medical Virology, Ruhr University Bochum) E Eike Steinmann (Department for Molecular and Medical Virology, Ruhr University Bochum) S Stephanie Pfaender (Department for Molecular and Medical Virology, Ruhr University Bochum)

Abstract

Mycophenolic acid (MPA) is commonly used in immunosuppressive regimens following solid organ transplantation. We demonstrate that MPA treatment reproducibly inhibits the replication of a range of viruses, including severe respiratory syndrome coronavirus 2 (SARS-CoV-2). Mechanistically, we identified cellular guanosine triphosphate pool depletion as a key mediator of this antiviral effect. Strikingly, this inhibition can be overcome which was correlated with the emergence of three breakthrough mutations in the SARS-CoV-2 genome (S P812R, ORF3 Q185H, and E S6L). Subsequent analyses confirmed that the combination of these mutations conferred accelerated replication kinetics, higher viral titers, and more rapid onset of cytopathic effects, but not MPA resistance. Comparison of global transcriptional responses to infection highlighted dysregulation of specific cellular gene programs under MPA treatment prior to breakthrough mutation emergence. Together, these findings identify viral and host drivers of variant emergence under immunosuppression. They also advocate for close monitoring of immunosuppressed patients, where emergence of novel viral variants with a fitness advantage may arise.

Article Details

Volume / Issue Vol. 122, Issue 28
Published July 15, 2025
ISSN 0027-8424
Publisher National Academy of Sciences

Authors (27)

T

Toni Luise Meister

Department for Molecular and Medical Virology, Ruhr University Bochum

M

Maximilian K. Nocke

Department for Molecular and Medical Virology, Ruhr University Bochum

N

Natalie Heinen

Department for Molecular and Medical Virology, Ruhr University Bochum

T

Thomas L. Burkard

Department for Molecular and Medical Virology, Ruhr University Bochum

Y

Yannick Brüggemann

Department for Molecular and Medical Virology, Ruhr University Bochum

S

Saskia Westhoven

Department for Molecular and Medical Virology, Ruhr University Bochum

B

Bettina Trüeb

Institute of Virology and Immunology, Bern and Mittelhäusern

N

Nadine Ebert

Institute of Virology and Immunology, Bern and Mittelhäusern

L

Lisa Thomann

Institute of Virology and Immunology, Bern and Mittelhäusern

K

Krzysztof P. Lubieniecki

Department of Human Genetics, Ruhr University Bochum

J

Joanna M. Lubieniecka

Department of Human Genetics, Ruhr University Bochum

K

Kristina Döring

M

Maike Herrmann

Section VET5 - Veterinary Medicine Research, Paul Ehrlich Institute

S

Sibylle Haid

TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture between Helmholtz-Centre for Infection Research and Hannover Medical School

T

Thomas Pietschmann

TWINCORE, Centre for Experimental and Clinical Infection Research, A Joint Venture between Helmholtz-Centre for Infection Research and Hannover Medical School

B

Bettina Wiegmann

Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School

R

Ronny Tao

Institute of Virology, Medical Faculty, Heinrich-Heine-University

S

Susanne Pfefferle

Institute of Medical Microbiology, Virology and Hygiene, Centre for Diagnostics, University Medical Centre Hamburg-Eppendorf

M

Marylyn M. Addo

Institute for Infection Research and Vaccine Development, Centre for Internal Medicine, University Medical Centre Hamburg-Eppendorf

V

Volker Thiel

Institute of Virology and Immunology, Bern and Mittelhäusern

I

Ingo Drexler

Institute of Virology, Medical Faculty, Heinrich-Heine-University

N

Nina Babel

Medical Department I, Centre for Translational Medicine and Immune Diagnostics Laboratory, Marien Hospital Herne, University Hospital of the Ruhr-University Bochum

H

Huu Phuc Nguyen

Department of Human Genetics, Ruhr University Bochum

R

Richard J. P. Brown

Department for Molecular and Medical Virology, Ruhr University Bochum

D

Daniel Todt

Department for Molecular and Medical Virology, Ruhr University Bochum

E

Eike Steinmann

Department for Molecular and Medical Virology, Ruhr University Bochum

S

Stephanie Pfaender

Department for Molecular and Medical Virology, Ruhr University Bochum