Lin, Y.-T., Chiweshe, S., McCormick, D., Raper, A., Wickenhagen, A., DeFillipis, V., Gaunt, E., Simmonds, P., Wilson, S. J. and Grey, F. (2020) Human cytomegalovirus evades ZAP detection by suppressing CpG dinucleotides in the major immediate early 1 gene. PLoS Pathogens, 16(9), e1008844. (doi: 10.1371/journal.ppat.1008844) (PMID:32886716) (PMCID:PMC7498042)
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Abstract
The genomes of RNA and small DNA viruses of vertebrates display significant suppression of CpG dinucleotide frequencies. Artificially increasing dinucleotide frequencies results in substantial attenuation of virus replication, suggesting that these compositional changes may facilitate recognition of non-self RNA sequences. Recently, the interferon inducible protein ZAP, was identified as the host factor responsible for sensing CpG in viral RNA, through direct binding and possibly downstream targeting for degradation. Using an arrayed interferon stimulated gene expression library screen, we identified ZAPS, and its associated factor TRIM25, as inhibitors of human cytomegalovirus (HCMV) replication. Exogenous expression of ZAPS and TRIM25 significantly reduced virus replication while knockdown resulted in increased virus replication. HCMV displays a strikingly heterogeneous pattern of CpG representation with specific suppression of CpG motifs within the IE1 major immediate early transcript which is absent in subsequently expressed genes. We demonstrated that suppression of CpG dinucleotides in the IE1 gene allows evasion of inhibitory effects of ZAP. We show that acute virus replication is mutually exclusive with high levels of cellular ZAP, potentially explaining the higher levels of CpG in viral genes expressed subsequent to IE1 due to the loss of pressure from ZAP in infected cells. Finally, we show that TRIM25 regulates alternative splicing between the ZAP short and long isoforms during HCMV infection and interferon induction, with knockdown of TRIM25 resulting in decreased ZAPS and corresponding increased ZAPL expression. These results demonstrate for the first time that ZAP is a potent host restriction factor against large DNA viruses and that HCMV evades ZAP detection through suppression of CpG dinucleotides within the major immediate early 1 transcript. Furthermore, TRIM25 is required for efficient upregulation of the interferon inducible short isoform of ZAP through regulation of alternative splicing.
Item Type: | Articles |
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Additional Information: | This project was funded by the Medical Research Council (https://mrc.ukri.org) MR/N001796/1 (FG), MR/K024752/1 (SJW), MC_UU_12014/10 (SJW) and MR/P022642/1 (SJW), the Biotechnology and Biological Sciences Research Council (https://bbsrc.ukri.org), BBS/E/D/ 20002172 (FG), Wellcome, https://wellcome.ac.uk, WT103767MA (PS) and through the Principal’s Career Development PhD scholarship from the University of Edinburgh (FG). |
Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Wilson, Professor Sam and Wickenhagen, Mr Arthur |
Creator Roles: | Wickenhagen, A.Methodology Wilson, S. J.Conceptualization, Funding acquisition, Resources, Writing – review and editing |
Authors: | Lin, Y.-T., Chiweshe, S., McCormick, D., Raper, A., Wickenhagen, A., DeFillipis, V., Gaunt, E., Simmonds, P., Wilson, S. J., and Grey, F. |
College/School: | College of Medical Veterinary and Life Sciences > School of Infection & Immunity College of Medical Veterinary and Life Sciences > School of Infection & Immunity > Centre for Virus Research |
Journal Name: | PLoS Pathogens |
Publisher: | Public Library of Science |
ISSN: | 1553-7366 |
ISSN (Online): | 1553-7374 |
Copyright Holders: | Copyright © 2020 The Authors |
First Published: | First published in PLoS Pathogens 16(9):e1008844 |
Publisher Policy: | Reproduced under a Creative Commons License |
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