title: Guanylate-Binding Protein 1, an Interferon-Induced GTPase, Exerts an Antiviral Activity against Classical Swine Fever Virus Depending on Its GTPase Activity.
abstract: Many viruses trigger the type I interferon (IFN) pathway upon infection, resulting in the transcription of hundreds of interferon-stimulated genes (ISGs), which define the antiviral state of the host. Classical swine fever virus (CSFV) is the causative agent of classical swine fever (CSF), a highly contagious viral disease endangering the pig industry in many countries. However, anti-CSFV ISGs are poorly documented. Here we screened 20 ISGs that are commonly induced by type I IFNs against CSFV in lentivirus-delivered cell lines, resulting in the identification of guanylate-binding protein 1 (GBP1) as a potent anti-CSFV ISG. We observed that overexpression of GBP1, an IFN-induced GTPase, remarkably suppressed CSFV replication, whereas knockdown of endogenous GBP1 expression by small interfering RNAs significantly promoted CSFV growth. Furthermore, we demonstrated that GBP1 acted mainly on the early phase of CSFV replication and inhibited the translation efficiency of the internal ribosome entry site of CSFV. In addition, we found that GBP1 was upregulated at the transcriptional level in CSFV-infected PK-15 cells and in various organs of CSFV-infected pigs. Coimmunoprecipitation and glutathione S-transferase (GST) pulldown assays revealed that GBP1 interacted with the NS5A protein of CSFV, and this interaction was mapped in the N-terminal globular GTPase domain of GBP1. Interestingly, the K51 of GBP1, which is crucial for its GTPase activity, was essential for the inhibition of CSFV replication. We showed further that the NS5A-GBP1 interaction inhibited GTPase activity, which was critical for its antiviral effect. Taking our findings together, GBP1 is an anti-CSFV ISG whose action depends on its GTPase activity.
  
  
  OBJECTIVE
  Classical swine fever virus (CSFV) is the causative agent of classical swine fever (CSF), an economically important viral disease affecting the pig industry in many countries. To date, only a few host restriction factors against CSFV, including interferon-stimulated genes (ISGs), have been characterized. Using a minilibrary of porcine ISGs, we identify porcine guanylate-binding protein 1 (GBP1) as a potent antiviral ISG against CSFV. We further show that the anti-CSFV action of GBP1 depends on its GTPase activity. The K51 of GBP1, critical for its GTPase activity, is essential for the antiviral action of GBP1 against CSFV replication, and the binding of the NS5A protein to GBP1 antagonizes the GTPase activity and thus the antiviral effect. This study will facilitate the development of anti-CSFV therapeutic agents by targeting host factors and may provide a new strategy for the control of CSF.
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Lian-Feng
authors.initials: LF
authors.lastname: Li
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Jiahui
authors.initials: J
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Jinghan
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Su
authors.initials: S
authors.lastname: Li
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Lingkai
authors.initials: L
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Shui-Li
authors.initials: SL
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Shaoxiong
authors.initials: S
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Yuzi
authors.initials: Y
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Northeast Agricultural University, Harbin, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: The Pirbright Institute, Pirbright, Woking, United Kingdom.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Munir
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China huajiqiu@hvri.ac.cn.
authors.forename: Hua-Ji
authors.initials: HJ
authors.lastname: Qiu
mesh_terms: D000818:Animals; D002460:Cell Line; D006691:Classical Swine Fever / Q000235:genetics / Q000378:metabolism* / Q000821:virology*; D006692:Classical Swine Fever Virus / Q000502:physiology*; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D054884:Host-Pathogen Interactions; D006801:Humans; D016899:Interferon-beta / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D013552:Swine; D014763:Viral Matrix Proteins; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000378:metabolism; D014779:Virus Replication
chemical_list: D034741:RNA, Small Interfering; D014763:Viral Matrix Proteins; D017361:Viral Nonstructural Proteins; D016899:Interferon-beta; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins