Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve after its emergence. Given its importance in viral infection and vaccine development, mutations in the viral Spike gene have been studied extensively; however, the impact of mutations outside the Spike gene are poorly understood. Here, we report that a triple deletion (ΔSGF or ΔLSG) in nonstructural protein 6 (nsp6) independently acquired in Alpha and Omicron sublineages of SARS-CoV-2 augments nsp6-mediated antagonism of type-I interferon (IFN-I) signaling. Specifically, these triple deletions enhance the ability of mutant nsp6 to suppress phosphorylation of STAT1 and STAT2. A parental SARS-CoV-2 USA-WA1/2020 strain containing the nsp6 ΔSGF deletion (ΔSGF-WA1) shows reduced susceptibility to IFN-I treatment in vitro, outcompetes the parental strain in human primary airway cultures, and increases virulence in mice; however, the ΔSGF-WA1 virus is less virulent than the Alpha variant (which has the nsp6 ΔSGF deletion and additional mutations in other genes). Analyses of host responses from ΔSGF-WA1-infected mice and primary airway cultures reveal activation of pathways indicative of a cytokine storm. These results provide evidence that mutations outside the Spike protein affect virus-host interactions and may alter pathogenesis of SARS-CoV-2 variants in humans.

Details

Title
Mutations in SARS-CoV-2 variant nsp6 enhance type-I interferon antagonism
Author
Bills, Cody J 1 ; Xia, Hongjie 1 ; John Yun-Chung Chen 1 ; Yeung, Jason 1 ; Kalveram, Birte K 2 ; Walker, David 3 ; Xie, Xuping 4 ; Pei-Yong, Shi 5 

 Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA 
 Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA 
 Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, USA 
 Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; Sealy Institute for Drug Discovery, University of Texas Medical Branch, Galveston, TX, USA 
 Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA; Sealy Institute for Drug Discovery, University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infection and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Institute for Translational Sciences, University of Texas Medical Branch, Galveston, TX, USA; Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, USA; Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA 
Publication year
2023
Publication date
Dec 2023
Publisher
Taylor & Francis Ltd.
e-ISSN
22221751
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2867483705
Copyright
© 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group, on behalf of Shanghai Shangyixun Cultural Communication Co., Ltd. This work is licensed under the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.