scholarly journals The acidic domain of the hepatitis C virus NS4A protein is required for viral assembly and envelopment through interactions with the viral E1 glycoprotein

2019 ◽  
Vol 15 (2) ◽  
pp. e1007163 ◽  
Author(s):  
Allison E. Roder ◽  
Christine Vazquez ◽  
Stacy M. Horner
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Assembly ◽  
Acidic Domain

scholarly journals The Acidic Domain of Hepatitis C Virus NS4A Contributes to RNA Replication and Virus Particle Assembly

2010 ◽  
Vol 85 (3) ◽  
pp. 1193-1204 ◽  
Author(s):  
T. Phan ◽  
A. Kohlway ◽  
P. Dimberu ◽  
A. M. Pyle ◽  
B. D. Lindenbach
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Particle ◽  
Rna Replication ◽  
Particle Assembly ◽  
Acidic Domain

scholarly journals Hepatitis C Virus-Induced Rab32 Aggregation and Its Implications for Virion Assembly

2016 ◽  
Vol 91 (3) ◽  
Author(s):  
Tu M. Pham ◽  
Si C. Tran ◽  
Yun-Sook Lim ◽  
Soon B. Hwang
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Membrane Trafficking ◽  
Core Protein ◽  
Cell Types ◽  
Viral Assembly ◽  
Intracellular Membrane ◽  
Virion Assembly ◽  
Hcv Core Protein ◽  
Infected Cells

ABSTRACT Hepatitis C virus (HCV) is highly dependent on cellular factors for viral propagation. Using high-throughput next-generation sequencing, we analyzed the host transcriptomic changes and identified 30 candidate genes which were upregulated in cell culture-grown HCV (HCVcc)-infected cells. Of these candidates, we selected Rab32 for further investigation. Rab32 is a small GTPase that regulates a variety of intracellular membrane-trafficking events in various cell types. In this study, we demonstrated that both mRNA and protein levels of Rab32 were increased in HCV-infected cells. Furthermore, we showed that HCV infection converted the predominantly expressed GTP-bound Rab32 to GDP-bound Rab32, contributing to the aggregation of Rab32 and thus making it less sensitive to cellular degradation machinery. In addition, GDP-bound Rab32 selectively interacted with HCV core protein and deposited core protein into the endoplasmic reticulum (ER)-associated Rab32-derived aggregated structures in the perinuclear region, which were likely to be viral assembly sites. Using RNA interference technology, we demonstrated that Rab32 was required for the assembly step but not for other stages of the HCV life cycle. Taken together, these data suggest that HCV may modulate Rab32 activity to facilitate virion assembly. IMPORTANCE Rab32, a member of the Ras superfamily of small GTPases, regulates various intracellular membrane-trafficking events in many cell types. In this study, we showed that HCV infection concomitantly increased Rab32 expression at the transcriptional level and altered the balance between GDP- and GTP-bound Rab32 toward production of Rab32-GDP. GDP-bound Rab32 selectively interacted with HCV core protein and enriched core in the ER-associated Rab32-derived aggregated structures that were probably necessary for viral assembly. Indeed, we showed that Rab32 was specifically required for the assembly of HCV. Collectively, our study identifies that Rab32 is a novel host factor essential for HCV particle assembly.

scholarly journals Hepatitis C virus infection activates an innate pathway involving IKK-α in lipogenesis and viral assembly

2013 ◽  
Vol 19 (6) ◽  
pp. 722-729 ◽  
Author(s):  
Qisheng Li ◽  
Véronique Pène ◽  
Siddharth Krishnamurthy ◽  
Helen Cha ◽  
T Jake Liang
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Infection ◽  
Viral Assembly ◽  
Hepatitis C Virus Infection

scholarly journals The acidic domain of the hepatitis C virus NS4A protein is required for viral assembly and envelopment through interactions with the viral E1 glycoprotein

2018 ◽  
Author(s):  
Allison E. Roder ◽  
Stacy M. Horner
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Particle ◽  
Particle Production ◽  
Infectious Virus ◽  
Core Protein ◽  
Viral Rna ◽  
Hcv Rna ◽  
Acidic Domain ◽  
Viral Particle Production

AbstractHepatitis C virus (HCV) assembly and envelopment are coordinated by a complex protein interaction network that includes most of the viral structural and nonstructural proteins. While the nonstructural protein 4A (NS4A) is known to be important for viral particle production, the specific function of NS4A in this process is not well understood. We performed mutagenesis of the C-terminal acidic domain of NS4A and found that mutation of several of these amino acids prevented the formation of the viral envelope, and therefore the production of infectious virions, without affecting viral RNA replication. In an overexpression system, we found that NS4A interacted with several viral proteins known to coordinate envelopment, including the viral E1 glycoprotein. One of the NS4A C-terminal mutations, Y45F, disrupted the interaction of NS4A with E1. Specifically, NS4A interacted with the first hydrophobic region of E1, a region previously described as regulating viral particle production. Supernatants from HCV NS4A Y45F transfected cells had significantly reduced levels of HCV RNA, however they contained equivalent levels of Core protein. Interestingly, the Core protein secreted from these cells formed high order oligomers with a density matching the infectious virus secreted from WT cells. These results suggest that this Y45F mutation in NS4A causes secretion of low density Core particles devoid of genomic HCV RNA. These results corroborate previous findings showing that mutation of the first hydrophobic region of E1 also causes secretion of Core complexes lacking RNA, and therefore suggest that the interaction between NS4A and E1 is involved in the incorporation of viral RNA into infectious HCV particles. Our findings define a new role for NS4A in the HCV lifecycle and help elucidate the protein interactions necessary for production of infectious virus.Author SummaryRNA viruses, which encompass both established and emerging pathogens, pose significant public health challenges. Viruses in the familyFlavivirdae, including Dengue virus, Zika virus and hepatitis C virus (HCV), continue to cause morbidity and mortality worldwide. One HCV protein, NS4A, has known functions in several steps of the viral lifecycle, however, how it contributes to viral particle production is not understood. Here, we investigated the role of one region of NS4A, the C-terminal acidic domain, in regulating the viral lifecycle. We found that some of the amino acids within this domain are important for viral envelopment to make infectious particles, specifically through interaction with the E1 glycoprotein. NS4A interacts with the first hydrophobic domain of E1. Disruption of this interaction prevents the production of infectious virus particles and instead results in release of low density Core protein complexes that lack HCV RNA into the cellular supernatant. Overall, our results reveal that NS4A is important for late stages of the HCV lifecycle and suggest that the interaction between NS4A and E1 may regulate the incorporation of viral RNA into the virion for the formation of infectious HCV particles.

scholarly journals N-Myc Downstream-Regulated Gene 1 Restricts Hepatitis C Virus Propagation by Regulating Lipid Droplet Biogenesis and Viral Assembly

2017 ◽  
Vol 92 (2) ◽  
Author(s):  
Cameron J. Schweitzer ◽  
Fang Zhang ◽  
Audrey Boyer ◽  
Kristin Valdez ◽  
Maggie Cam ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Liver Cancer ◽  
Lipid Droplet ◽  
Viral Infections ◽  
Rna Virus ◽  
Viral Assembly ◽  
Hcv Infection ◽  
Host Cells ◽  
Virus Propagation

ABSTRACT Host cells harbor various intrinsic mechanisms to restrict viral infections as a first line of antiviral defense. Viruses have evolved various countermeasures against these antiviral mechanisms. Here we show that N-Myc downstream-regulated gene 1 (NDRG1) limits productive hepatitis C virus (HCV) infection by inhibiting viral assembly. Interestingly, HCV infection downregulates NDRG1 protein and mRNA expression. The loss of NDRG1 increases the size and number of lipid droplets, which are the sites of HCV assembly. HCV suppresses NDRG1 expression by upregulating MYC, which directly inhibits the transcription of NDRG1. The upregulation of MYC also leads to the reduced expression of the NDRG1-specific kinase serum/glucocorticoid-regulated kinase 1 (SGK1), resulting in a markedly diminished phosphorylation of NDRG1. The knockdown of MYC during HCV infection rescues NDRG1 expression and phosphorylation, suggesting that MYC regulates NDRG1 at both the transcriptional and posttranslational levels. Overall, our results suggest that NDRG1 restricts HCV assembly by limiting lipid droplet formation. HCV counteracts this intrinsic antiviral mechanism by downregulating NDRG1 via a MYC-dependent mechanism. IMPORTANCE Hepatitis C virus (HCV) is an enveloped single-stranded RNA virus that targets hepatocytes in the liver. HCV is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma, and estimates suggest a global prevalence of 2.35%. Up to 80% of acutely infected individuals will develop chronic infection, and as many as 5% eventually progress to liver cancer. An understanding of the mechanisms behind virus-host interactions and viral carcinogenesis is still lacking. The significance of our research is that it identifies a previously unknown relationship between HCV and a known tumor-associated gene. Furthermore, our data point to a new role for this gene in the liver and in lipid metabolism. Thus, HCV infection serves as a great biological model to advance our knowledge of liver functions and the development of liver cancer.

scholarly journals Phosphatidylserine-Specific Phospholipase A1 Involved in Hepatitis C Virus Assembly through NS2 Complex Formation

2014 ◽  
Vol 89 (4) ◽  
pp. 2367-2377 ◽  
Author(s):  
Min Guo ◽  
Rongjuan Pei ◽  
Qi Yang ◽  
Huang Cao ◽  
Yun Wang ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Complex Formation ◽  
Protein Localization ◽  
Protein Translation ◽  
Viral Assembly ◽  
Host Factor ◽  
Hcv Infection ◽  
Phospholipase A1 ◽  
Replication Complex

ABSTRACTSeveral members of the phospholipase family have been reported to be involved in hepatitis C virus (HCV) replication. Here, we identified another phospholipase, phosphatidylserine-specific phospholipase A1 (PLA1A), as a host factor involved in HCV assembly. PLA1A was upregulated by HCV infection, and PLA1A knockdown significantly reduced J399EM (genotype 2a) HCV propagation at the assembly step but not the entry, RNA replication, and protein translation steps of the life cycle. Protein localization and interaction analysis further revealed a role of PLA1A in the interaction of NS2-E2 and NS2-NS5A, as the formation of the NS2-E2 and NS2-NS5A complexes was weakened in the absence of PLA1A. In addition, PLA1A stabilized the NS2/NS5A dotted structure during infection. These data suggest that PLA1A plays an important role in bridging the membrane-associated NS2-E2 complex and the NS5A-associated replication complex via its interaction with E2, NS2, and NS5A, which leads to a coordinating interaction between the structural and nonstructural proteins and facilitates viral assembly.IMPORTANCEHepatitis C virus (HCV) genomic replication is driven by the replication complex and occurs at the membranous web, while the lipid droplet is the organelle in which virion assembly is initiated. In this study, we identified phosphatidylserine-specific phospholipase A1 (PLA1A), a member of phospholipase A 1 family, as a novel host factor involved in the assembly process of HCV. PLA1A, which is induced by HCV infection at a late infection stage, interacts with HCV E2, NS2, and NS5A proteins and enhances and stabilizes the NS2-E2 and NS2-NS5A complex formation, which is essential for viral assembly. Thus, PLA1A is an important host factor which is involved in the initiation of the viral assembly in close proximity to Core-decorated lipid droplets through bringing together the HCV replication complex and envelope complex.

Interfering with hepatitis C virus assembly in vitro using affinity peptides directed towards core protein

2012 ◽  
Vol 58 (4) ◽  
pp. 475-482
Author(s):  
Jean-Baptiste Duvignaud ◽  
Nathalie Majeau ◽  
Priscilla Delisle ◽  
Normand Voyer ◽  
Stéphane M. Gagné ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Self Assembly ◽  
Core Protein ◽  
Virus Assembly ◽  
Viral Assembly ◽  
Structural Protein ◽  
Ns5a Protein ◽  
The Core

Viral assembly is a crucial key step in the life cycle of every virus. In the case of Hepatitis C virus (HCV), the core protein is the only structural protein to interact directly with the viral genomic RNA. Purified recombinant core protein is able to self-assemble in vitro into nucleocapsid-like particles upon addition of a structured RNA, providing a robust assay with which to study HCV assembly. Inhibition of self-assembly of the C170 core protein (first 170 amino acids) was tested using short peptides derived from the HCV core, from HCV NS5A protein, and from diverse proteins (p21 and p73) known to interact with HCV core protein. Interestingly, peptides derived from the core were the best inhibitors. These peptides are derived from regions of the core predicted to be involved in the interaction between core subunits during viral assembly. We also demonstrated that a peptide derived from the C-terminal end of NS5A protein moderately inhibits the assembly process.

scholarly journals Identification and Targeting of an Interaction between a Tyrosine Motif within Hepatitis C Virus Core Protein and AP2M1 Essential for Viral Assembly

2012 ◽  
Vol 8 (8) ◽  
pp. e1002845 ◽  
Author(s):  
Gregory Neveu ◽  
Rina Barouch-Bentov ◽  
Amotz Ziv-Av ◽  
Doron Gerber ◽  
Yves Jacob ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Core Protein ◽  
Viral Assembly ◽  
Virus Core

scholarly journals Rab18 is required for viral assembly of hepatitis C virus through trafficking of the core protein to lipid droplets

Virology ◽  
2014 ◽  
Vol 462-463 ◽  
pp. 166-174 ◽  
Author(s):  
Hiromichi Dansako ◽  
Hiroki Hiramoto ◽  
Masanori Ikeda ◽  
Takaji Wakita ◽  
Nobuyuki Kato
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Lipid Droplets ◽  
Core Protein ◽  
Viral Assembly ◽  
The Core
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