| Autor: |
Jiao Y; Department of Veterinary Medicine, Zhejiang University, Hangzhou, China.; Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China., Zhao P; Department of Biochemistry and Department of Cardiology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China., Xu LD; Department of Veterinary Medicine, Zhejiang University, Hangzhou, China.; MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, China., Yu JQ; Department of Veterinary Medicine, Zhejiang University, Hangzhou, China., Cai HL; Department of Veterinary Medicine, Zhejiang University, Hangzhou, China., Zhang C; Boehringer Ingelheim Vetmedica (China) Co. Ltd, Taizhou, China., Tong C; Boehringer Ingelheim Vetmedica (China) Co. Ltd, Taizhou, China., Yang YL; Department of Veterinary Medicine, Zhejiang University, Hangzhou, China., Xu P; MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, China., Sun Q; Department of Biochemistry and Department of Cardiology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China., Chen N; Boehringer Ingelheim Vetmedica (China) Co. Ltd, Taizhou, China., Wang B; Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China., Huang YW; Department of Veterinary Medicine, Zhejiang University, Hangzhou, China.; Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.; State Key Laboratory for Animal Disease Control and Prevention, South China Agricultural University, Guangzhou, China. |
| Abstrakt: |
Non-structural protein 2 (nsp2) exists in all coronaviruses (CoVs), while its primary function in viral pathogenicity, is largely unclear. One such enteric CoV, porcine epidemic diarrhea virus (PEDV), causes high mortality in neonatal piglets worldwide. To determine the biological role of nsp2, we generated a PEDV mutant containing a complete nsp2 deletion (rPEDV-Δnsp2) from a highly pathogenic strain by reverse genetics, showing that nsp2 was dispensable for PEDV infection, while its deficiency reduced viral replication in vitro . Intriguingly, rPEDV-Δnsp2 was entirely avirulent in vivo , with significantly increased productions of IFNB (interferon beta) and IFN-stimulated genes (ISGs) in various intestinal tissues of challenged newborn piglets. Notably, nsp2 targets and degrades TBK1 (TANK binding kinase 1), the critical kinase in the innate immune response. Mechanistically, nsp2 induced the macroautophagy/autophagy process and recruited a selective autophagic receptor, NBR1 (NBR1 autophagy cargo receptor). NBR1 subsequently facilitated the K48-linked ubiquitination of TBK1 and delivered it for autophagosome-mediated degradation. Accordingly, the replication of rPEDV-Δnsp2 CoV was restrained by reduced autophagy and excess productions of type I IFNs and ISGs. Our data collectively define enteric CoV nsp2 as a novel virulence determinant, propose a crucial role of nsp2 in diminishing innate antiviral immunity by targeting TBK1 for NBR1-mediated selective autophagy, and pave the way to develop a new type of nsp2-based attenuated PEDV vaccine. The study also provides new insights into the prevention and treatment of other pathogenic CoVs. Abbreviations : 3-MA: 3-methyladenine; Baf A1: bafilomycin A 1 ; CoV: coronavirus; CQ: chloroquine; dpi: days post-inoculation; DMVs: double-membrane vesicles; GABARAP: GABA type A receptor-associated protein; GFP: green fluorescent protein; GIGYF2: GRB10 interacting GYF protein 2; hpi: hours post-infection; IFA: immunofluorescence assay; IFIH1: interferon induced with helicase C domain 1; IFIT2: interferon induced protein with tetratricopeptide repeats 2; IFITM1: interferon induced transmembrane protein 1; IFNB: interferon beta; IRF3: interferon regulatory factor 3; ISGs: interferon-stimulated genes; mAb: monoclonal antibody; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAVS: mitochondrial antiviral signaling protein; NBR1: NBR1 autophagy cargo receptor; nsp2: non-structural protein 2; OAS1: 2'-5'-oligoadenylate synthetase 1; PEDV: porcine epidemic diarrhea virus; PRRs: pattern recognition receptors; RIGI: RNA sensor RIG-I; RT-qPCR: reverse transcription quantitative polymerase chain reaction; SQSTM1: sequestosome 1; TBK1: TANK binding kinase 1; TCID 50 : 50% tissue culture infectious doses; VSV: vesicular stomatitis virus. |
