Peste des Petits Ruminants Virus Nucleocapsid Protein Inhibits Beta Interferon Production by Interacting with IRF3 To Block Its Activation
Authors: Xiangtao Liu
Miaotao Zhang
Hong Tian
Weijun Cao
Wen Dang
Qinghong Xue
Keshan Zhang
Pengfei Li
Fan Yang
Zixiang Zhu
Xiangle Zhang
Xusheng Ma
Haixue Zheng
Journal: Journal of Virology (2019)
Discipline: MICROBIOLOGY
Keywords: IRF3; PPRV; immune suppression; nuclear translocation; nucleocapsid.
Affiliations: State Key Laboratory of Veterinary Etiological Biology, National Foot and Mouth Diseases Reference Laboratory, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China, College of Veterinary Medicine, Northwest A&amp;F University, Yangling, Shaanxi, China, China Institute of Veterinary Drug Control, Beijing, China

Abstract:  Peste des petits ruminants virus (PPRV) is the etiological agent of peste des petits ruminants, causing acute immunosuppression in its natural hosts. However, the molecular mechanisms by which PPRV antagonizes the host immune responses have not been fully characterized. In particular, how PPRV suppresses the activation of the host RIG-I-like receptor (RLR) pathway has yet to be clarified. In this study, we demonstrated that PPRV infection significantly suppresses RLR pathway activation and type I interferon (IFN) production and identified PPRV N protein as an extremely important antagonistic viral factor that suppresses beta interferon (IFN-Œ≤) and IFN-stimulated gene (ISG) expression. A detailed analysis showed that PPRV N protein inhibited type I IFN production by targeting interferon regulatory factor 3 (IRF3), a key molecule in the RLR pathway required for type I IFN induction. PPRV N protein interacted with IRF3 (but not with other components of the RLR pathway, including MDA5, RIG-I, VISA, TBK1, and MITA) and abrogated the phosphorylation of IRF3. As expected, PPRV N protein also considerably impaired the nuclear translocation of IRF3. The TBK1-IRF3 interaction was involved significantly in IRF3 phosphorylation, and we showed that PPRV N protein inhibits the association between TBK1 and IRF3, which in turn inhibits IRF3 phosphorylation. The amino acid region 106 to 210 of PPRV N protein was determined to be essential for suppressing the nuclear translocation of IRF3 and IFN-Œ≤ production, and the 140 to 400 region of IRF3 was identified as the crucial region for the N-IRF3 interaction. Together, our findings demonstrate a new mechanism evolved by PPRV to inhibit type I IFN production and provide structural insights into the immunosuppression caused by PPRV.IMPORTANCE Peste des petits ruminants is a highly contagious animal disease affecting small ruminants, which threatens both small livestock and endangered susceptible wildlife populations in many countries. The causative agent, peste des petits ruminants virus (PPRV), often causes acute immunosuppression in its natural hosts during infection. Here, for the first time, we demonstrate that N protein, the most abundant protein of PPRV, plays an extremely important role in suppression of interferon regulatory factor 3 (IRF3) function and type I interferon (IFN) production by interfering with the formation of the TBK1-IRF3 complex. This study explored a novel antagonistic mechanism of PPRV. 

Retracted: No

PubPeer comments:
 1. Itu2019s impossible that viral infection did not induce any IFN, both RNA andprotein, although virus has immune evasion mechanisms.  2. All results based on overexpression of viral protein, there is not any NP mutated viral infection data in the whole paper. 3. This is a goat virus, but the whole paper uses 293T cells to do all experiments, this made all results questionable. 4. For general viral infection, the whole paper did not show the MOI. , 
 PPRV is a goat virus that needs a specific receptor for entry, including SLAM or Nectin 4 which has been discovered, 293T cells definitely can not support the virus to grow. so that means the figure 3E is impossible to detect PPRV-N in 293T cells https: pubmed.ncbi.nlm.nih.gov 31167907 # gid=article-figures pid=fig-3-uid-3 , 
 I have been working with PPRV for many years . It is impossible for detecting N protein in 293T cells. I don t how JVI publish this paper with LOW quality. , 
 #1 Dear Artedidraco skottsbergi. I m the first author of this paper. Thanks for your interesting to our study. Actually speaking, many virus infections do not induce interferon (IFN) production. Such as, mouse hepatitis virus (MHV) does not induce interferon (IFN) production in fibroblasts or bone marrow-derived dendritic cells. (J Virol . 2007 Jan;81(2):568-74. doi: 10.1128 JVI.01512-06. Epub 2006 Nov 1.) https: journals.asm.org doi epub 10.1128 JVI.01512-06  SARS-CoV does not induce beta interferon in human 293 cell as well (J Virol . 2005 Feb;79(4):2079-86. doi: 10.1128 JVI.79.4.2079-2086.2005). https: journals.asm.org doi epub 10.1128 JVI.79.4.2079-2086.2005 .  We did find that PPRV infection did not induce IFN in HEK293T cells. As for your second question. We have performed the co-IP assay in the context of PPRV infection, which showed that the viral N protein interacts with IRF3 in the infected cells. We did not have a reverse genetical system, and therefore, we can not generate a recombiant virus. Many sheep antibodies have limitted the study of PPRV pathogenesis. HEK293T is a reported cell model for PPRV infection, and many studies have used HEK293T cells to study the pathogenesis of PPRV. Therefore, we used HEK293T cells to performed the study. https: www.ncbi.nlm.nih.gov pmc articles PMC7889028 pdf KVIR_12_1882246.pdf https: www.sciencedirect.com science article pii S1567134819301996 1 MOI of PPRV has been used in this study. Thanks. , 
 #2 HEK293T cells are permissive for PPRV infeciton. Many studies have confirmed this results. https: www.ncbi.nlm.nih.gov pmc articles PMC7889028 pdf KVIR_12_1882246.pdf https: www.sciencedirect.com science article pii S1567134819301996 , 
 #1 #1 Dear Artedidraco skottsbergi. I m the first author of this paper. Thanks for your interesting to our study. 1. Actually speaking, many viruses infection do not induce interferon (IFN) production. Such as, mouse hepatitis virus (MHV) does not induce interferon (IFN) production in fibroblasts or bone marrow-derived dendritic cells. (J Virol . 2007 Jan;81(2):568-74. doi: 10.1128 JVI.01512-06. Epub 2006 Nov 1.) https: journals.asm.org doi epub 10.1128 JVI.01512-06  SARS-CoV does not induce beta interferon in human 293 cell as well (J Virol . 2005 Feb;79(4):2079-86. doi: 10.1128 JVI.79.4.2079-2086.2005). https: journals.asm.org doi epub 10.1128 JVI.79.4.2079-2086.2005 .  We did find that PPRV infection did not induce IFN in HEK293T cells. 2. As for your second question. We have performed the co-IP assay in the context of PPRV infection, which showed that the viral N protein interacts with IRF3 in the infected cells. We did not have a reverse genetical system, and therefore, we can not generate a recombiant virus. 3. Many sheep antibodies have limitted the study of PPRV pathogenesis. HEK293T is a reported cell model for PPRV infection, and many studies have used HEK293T cells to study the pathogenesis of PPRV. Therefore, we used HEK293T cells to performed the study. https: www.ncbi.nlm.nih.gov pmc articles PMC7889028 pdf KVIR_12_1882246.pdf https: www.sciencedirect.com science article pii S1567134819301996 4. 1 MOI of PPRV has been used in our study. , 
 #2 HEK293T cells are permissive for PPRV infeciton. Many studies have confirmed this results. https: www.ncbi.nlm.nih.gov pmc articles PMC7889028 pdf KVIR_12_1882246.pdf https: www.sciencedirect.com science article pii S1567134819301996 https: www.sciencedirect.com science article pii S0378113521002091 , 
 #7 Previous studies have widely reported that HEK293T cells are permissive to PPRV infection. ,