Preprint Review Version 1 Preserved in Portico This version is not peer-reviewed

Attenuation and Degeneration of SARS-CoV-2 Despite of Adaptive Evolution

Yingguang Liu
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Version 1 : Received: 22 November 2022 / Approved: 23 November 2022 / Online: 23 November 2022 (03:29:58 CET)

A peer-reviewed article of this Preprint also exists.

Liu, Y. Attenuation and Degeneration of SARS-CoV-2 Despite Adaptive Evolution. Cureus, 2023. https://doi.org/10.7759/cureus.33316. Liu, Y. Attenuation and Degeneration of SARS-CoV-2 Despite Adaptive Evolution. Cureus, 2023. https://doi.org/10.7759/cureus.33316.

Abstract

Evolution of SARS-CoV-2 has followed similar trends as other RNA viruses, e.g., HIV-1 and influenza A. Rapid initial diversification was followed by strong competition and rapid succession of dominant variants. Host-initiated RNA editing has been the primary mechanism for introducing mutations. A significant number of mutations were detrimental and were quickly purged. Fixed mutations are mostly diversifying mutations selected for host adaptation and immune evasion, with the latter accounting for more of the changes. However, immune evasion often comes at the cost of functionality, so that optimal functionality is still far from being accomplished. Instead, selection for antibody-escaping variants and accumulation of near-neutral mutations has led to suboptimal codon usage and reduced replicative capacity as demonstrated in non-respiratory cell lines. Beneficial adaptation of the virus includes reduced infectivity in lung tissues and increased tropism for the upper airway, resulting in shorter incubation periods, milder diseases, and more efficient transmission between people.

Keywords

SARS-CoV-2, evolution, immune evasion, codon usage, attenuation, genome degradation, degeneration, COVID-19

Subject

Biology and Life Sciences, Virology

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Comments (1)

Comment 1
Received: 3 January 2023
Commenter:
Yingguang Liu
(Click to see Publons profile: )
The commenter has declared there is no conflict of interests.
Comment: Although this review focuses on the evidences of degenerative evolution and attenuation of SARS-CoV-2, the severity of COVID-19 is determined by both viral virulence and host immunity. Immunoevasion of SARS-CoV-2 causes vaccines and therapeutic antibodies to lose efficacy, resulting in severe pneumonia and multisystem infections. Even though milder nature of Omicron benefits the elderly more than the young, the senior population still suffers the most severe morbidity and the highest mortality. While viral degeneration offers some optimism for the future direction of viral evolution, we are still called to pray, to heal, and to diligently conduct biomedical research.
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