SARS-CoV-2 mutant spectrum complexity is an epidemiologically evolvable trait

B Brenda Martínez-González (Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)) M María Eugenia Soria (Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)) A Ana Isabel de Ávila (Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)) P Pilar Somovilla (Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)) C Claudia Aguilar-Sabido (Management Solutions, Torre Picasso) P Pablo Mínguez (Department of Genetics and Genomics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid) C Cristina Ferrer-Orta (Structural and Molecular Biology Department, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas) L Llanos Salar-Vidal (Department of Clinical Microbiology, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid) R Ramon Lorenzo-Redondo S Soledad Delgado (Departamento de Sistemas Informáticos, Escuela Técnica Superior de Ingeniería de Sistemas Informáticos, Universidad Politécnica de Madrid) F Federico Morán (Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid) N Nuria Verdaguer (Structural and Molecular Biology Department, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas) I Ignacio Gadea (Department of Clinical Microbiology, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid) E Esteban Domingo (Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)) C Celia Perales (Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid))

Abstract

RNA virus populations consist of complex and dynamic mutant spectra in which most individual genomes differ in one or more positions from the other genomes of the same population. This behavior, known as quasispecies dynamics, applies to SARS-CoV-2 which exhibits intrahost genetic and functional heterogeneity while evolving at a high rate in the human population. In the present study, we describe a remarkable reduction in mutant spectrum complexity (intrahost viral genome heterogeneity) in SARS-CoV-2 isolates of late relative to early COVID-19 waves, as they reached Madrid (Spain) from 2020 until 2022. In contrast, the consensus (average) sequence of the corresponding isolates displayed a continuing divergence from the initial Wuhan-Hu-1 virus as the pandemic advanced. The mutant spectrum complexity developed upon replication in Vero E6 cells of the isolates from the first and sixth COVID-19 waves, as well as of biological clones retrieved from them, was similar. Therefore, the mutant spectrum complexity reduction observed in vivo was not due to an increased accuracy of the viral replicative machinery, but rather to other factors related to viral epidemiology or pathogenesis. Such possible factors and their implications for viral trait modifications in the course of a viral pandemic are discussed. The results establish that mutant spectrum complexity of genetically variable viruses can be an epidemiologically evolvable trait.

Article Details

Volume / Issue Vol. 122, Issue 39
Published September 30, 2025
ISSN 0027-8424
Publisher National Academy of Sciences

Authors (15)

B

Brenda Martínez-González

Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)

M

María Eugenia Soria

Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)

A

Ana Isabel de Ávila

Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)

P

Pilar Somovilla

Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)

C

Claudia Aguilar-Sabido

Management Solutions, Torre Picasso

P

Pablo Mínguez

Department of Genetics and Genomics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid

C

Cristina Ferrer-Orta

Structural and Molecular Biology Department, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas

L

Llanos Salar-Vidal

Department of Clinical Microbiology, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid

R

Ramon Lorenzo-Redondo

S

Soledad Delgado

Departamento de Sistemas Informáticos, Escuela Técnica Superior de Ingeniería de Sistemas Informáticos, Universidad Politécnica de Madrid

F

Federico Morán

Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid

N

Nuria Verdaguer

Structural and Molecular Biology Department, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas

I

Ignacio Gadea

Department of Clinical Microbiology, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid

E

Esteban Domingo

Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)

C

Celia Perales

Microbes in Health and Welfare Program, Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas–Universidad Autónoma de Madrid)