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Research article

The host protein CALCOCO2 interacts with bovine viral diarrhoea virus Npro, inhibiting type I interferon production and thereby promoting viral replication

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Article: 2289764 | Received 10 Mar 2023, Accepted 27 Nov 2023, Published online: 04 Dec 2023
 

ABSTRACT

Bovine viral diarrhoea-mucosal disease caused by bovine viral diarrhoea virus (BVDV) is a major infectious disease that affects the cattle industry. The nonstructural protein Npro of BVDV antagonizes the type I interferon (IFN-I) pathway, thereby escaping the host immune response. The exact mechanism by which Npro uses host proteins to inhibit IFN-I production is unclear. The host protein CALCOCO2 was identified as a binding partner of Npro using a yeast two-hybrid screen. The interaction between Npro and CALCOCO2 was confirmed by yeast co-transformation, co-immunoprecipitation assays, and GST pull-down assays. The stable overexpression of CALCOCO2 markedly promoted BVDV propagation, while the knockdown of CALCOCO2 significantly inhibited BVDV replication in MDBK cells. Interestingly, CALCOCO2 inhibited IFN-I and IFN-stimulated gene production in BVDV-infected cells. Ectopic expression of CALCOCO2 effectively reduced IRF3 protein levels via the proteasome pathway. CALCOCO2 was found to promote Npro-mediated ubiquitination degradation of IRF3 by interacting with IRF3. Our results demonstrate the molecular mechanism by which Npro recruits the CALCOCO2 protein to regulate IRF3 degradation to inhibit IFN-I production.

Disclosure statement

The authors declare that the research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

Author contributions

W.S, L.FX, W.R, G.J, and M.XM performed most of the experiments. W.R, W.J, and M.Z participated in the discussion. H.HB. and W.HM supervised the work and revised the final version of the manuscript. All the authors have read and approved the final manuscript.

Data Availability statement

The data supporting this study’s findings are available from the corresponding author.

Additional information

Funding

This study was supported by grants from the Shandong Provincial Natural Science Foundation, China (ZR2022QC017), the Shandong Province Postdoctoral Special Funds for Innovative Projects under Grant SDCX-ZG-202203034, the China Postdoctoral Science Foundation (2022M721942), the National Natural Science Foundation of China (31902257 and 32072834), and the earmarked fund for the Taishan Scholar Project NO.tspd20181207.