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Netherton CL, Shimmon GL, Hui JYK, Connell S, Reis AL. African Swine Fever Virus Host-Pathogen Interactions. Subcell Biochem 2023; 106:283-331. [PMID: 38159232 DOI: 10.1007/978-3-031-40086-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
African swine fever virus is a complex double-stranded DNA virus that exhibits tropism for cells of the mononuclear phagocytic system. Virus replication is a multi-step process that involves the nucleus of the host cell as well the formation of large perinuclear sites where progeny virions are assembled prior to transport to, and budding through, the plasma membrane. Like many viruses, African swine fever virus reorganises the cellular architecture to facilitate its replication and has evolved multiple mechanisms to avoid the potential deleterious effects of host cell stress response pathways. However, how viral proteins and virus-induced structures trigger cellular stress pathways and manipulate the subsequent responses is still relatively poorly understood. African swine fever virus alters nuclear substructures, modulates autophagy, apoptosis and the endoplasmic reticulum stress response pathways. The viral genome encodes for at least 150 genes, of which approximately 70 are incorporated into the virion. Many of the non-structural genes have not been fully characterised and likely play a role in host range and modifying immune responses. As the field moves towards approaches that take a broader view of the effect of expression of individual African swine fever genes, we summarise how the different steps in virus replication interact with the host cell and the current state of knowledge on how it modulates the resulting stress responses.
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Zhong H, Fan S, Du Y, Zhang Y, Zhang A, Jiang D, Han S, Wan B, Zhang G. African Swine Fever Virus MGF110-7L Induces Host Cell Translation Suppression and Stress Granule Formation by Activating the PERK/PKR-eIF2α Pathway. Microbiol Spectr 2022; 10:e0328222. [PMID: 36377947 PMCID: PMC9769596 DOI: 10.1128/spectrum.03282-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 10/30/2022] [Indexed: 11/16/2022] Open
Abstract
African swine fever (ASF) is a highly contagious and often lethal disease of pigs caused by ASF virus (ASFV) and recognized as the biggest killer in global swine industry. Despite exhibiting incredible self-sufficiency, ASFV remains unconditionally dependent on the host translation machinery for its mRNA translation. However, less is yet known regarding how ASFV-encoded proteins regulate host translation machinery in infected cells. Here, we examined how ASFV interacts with the eukaryotic initiation factor 2α (eIF2α) signaling axis, which directs host translation control and adaptation to cellular stress. We found that ASFV MGF110-7L, a previously uncharacterized member of the multigene family 110, remarkably enhanced the phosphorylation level of eIF2α. In porcine alveolar macrophage 3D4/21 and porcine kidney-15 cells, MGF110-7L triggered eIF2α signaling and the integrated stress response, resulting in the suppression of host translation and the formation of stress granules (SGs). Mechanistically, MGF110-7L-induced phosphorylation of eIF2α was mediated via protein kinase R (PKR) and PKR-like endoplasmic reticulum (ER) kinase (PERK), and this process was essential for host translation repression and SG formation. Notably, our subsequent analyses confirmed that MGF110-7L was overwhelmingly retained in the ER and caused a specific reorganization of the secretory pathway. Further proteomic analyses and biochemical experiments revealed that MGF110-7L could trigger ER stress and activate the unfolded protein response, thus contributing to eIF2α phosphorylation and translation reprogramming. Overall, our study both identifies a novel mechanism by which ASFV MGF110-7L subverts the host protein synthesis machinery and provides further insights into the translation regulation that occurs during ASFV infection. IMPORTANCE African swine fever (ASF) has become a socioeconomic burden and a threat to food security and biodiversity, but no commercial vaccines or antivirals are available currently. Understanding the viral strategies to subvert the host translation machinery during ASF virus (ASFV) infection could potentially lead to new vaccines and antiviral therapies. In this study, we dissected how ASFV MGF110-7L interacts with the eIF2α signaling axis controlling translational reprogramming, and we addressed the role of MGF110-7L in induction of cellular stress responses, eIF2α phosphorylation, translation suppression, and stress granule formation. These results define several molecular interfaces by which ASFV MGF110-7L subverts host cell translation, which may guide research on antiviral strategies and dissection of ASFV pathogenesis.
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Affiliation(s)
- Han Zhong
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Shuai Fan
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Yongkun Du
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
- Henan Engineering Laboratory of Animal Biological Products, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Yuhang Zhang
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Angke Zhang
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Dawei Jiang
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
- Henan Engineering Laboratory of Animal Biological Products, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Shichong Han
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Bo Wan
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
- Henan Engineering Laboratory of Animal Biological Products, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
| | - Gaiping Zhang
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People’s Republic of China
- Longhu Laboratory, Zhengzhou, Henan, People’s Republic of China
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Legionella pneumophila Infection of Human Macrophages Retains Golgi Structure but Reduces O-Glycans. Pathogens 2022; 11:pathogens11080908. [PMID: 36015029 PMCID: PMC9415278 DOI: 10.3390/pathogens11080908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/02/2022] [Accepted: 08/08/2022] [Indexed: 11/30/2022] Open
Abstract
Legionella pneumophila is an accidental pathogen that replicates intracellularly within the Legionella-containing vacuole (LCV) in macrophages. Within an hour of infection, L. pneumophila secretes effectors to manipulate Rab1 and intercept ER-derived vesicles to the LCV. The downstream consequences of interrupted ER trafficking on the Golgi of macrophages are not clear. We examined the Golgi structure and function in L. pneumophila-infected human U937 macrophages. Intriguingly, the size of the Golgi in infected macrophages remained similar to uninfected macrophages. Furthermore, TEM analysis also did not reveal any significant changes in the ultrastructure of the Golgi in L. pneumophila-infected cells. Drug-induced Golgi disruption impacted bacterial replication in human macrophages, suggesting that an intact organelle is important for bacteria growth. To probe for Golgi functionality after L. pneumophila infection, we assayed glycosylation levels using fluorescent lectins. Golgi O-glycosylation levels, visualized by the fluorescent cis-Golgi lectin, Helix pomatia agglutinin (HPA), significantly decreased over time as infection progressed, compared to control cells. N-glycosylation levels in the Golgi, as measured by L-PHA lectin staining, were not impacted by L. pneumophila infection. To understand the mechanism of reduced O-glycans in the Golgi we monitored UDP-GalNAc transporter levels in infected macrophages. The solute carrier family 35 membrane A2 (SLC35A2) protein levels were significantly reduced in L. pneumophila-infected U937 and HeLa cells and L. pneumophila growth in human macrophages benefitted from GalNAc supplementation. The pronounced reduction in Golgi HPA levels was dependent on the translocation apparatus DotA expression in bacteria and occurred in a ubiquitin-independent manner. Thus, L. pneumophila infection of human macrophages maintains and requires an intact host Golgi ultrastructure despite known interference of ER–Golgi trafficking. Finally, L. pneumophila infection blocks the formation of O-linked glycans and reduces SLC35A2 protein levels in infected human macrophages.
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Influenza A Virus Infection Activates NLRP3 Inflammasome through Trans-Golgi Network Dispersion. Viruses 2022; 14:v14010088. [PMID: 35062292 PMCID: PMC8778788 DOI: 10.3390/v14010088] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 02/05/2023] Open
Abstract
The NLRP3 inflammasome consists of NLRP3, ASC, and pro-caspase-1 and is an important arm of the innate immune response against influenza A virus (IAV) infection. Upon infection, the inflammasome is activated, resulting in the production of IL-1β and IL-18, which recruits other immune cells to the site of infection. It has been suggested that in the presence of stress molecules such as nigericin, the trans-Golgi network (TGN) disperses into small puncta-like structures where NLRP3 is recruited and activated. Here, we investigated whether IAV infection could lead to TGN dispersion, whether dispersed TGN (dTGN) is responsible for NLRP3 inflammasome activation, and which viral protein is involved in this process. We showed that the IAV causes dTGN formation, which serves as one of the mechanisms of NLRP3 inflammasome activation in response to IAV infection. Furthermore, we generated a series of mutant IAVs that carry mutations in the M2 protein. We demonstrated the M2 proton channel activity, specifically His37 and Trp41 are pivotal for the dispersion of TGN, NLRP3 conformational change, and IL-1β induction. The results revealed a novel mechanism behind the activation and regulation of the NLRP3 inflammasome in IAV infection.
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Aistleitner K, Clark T, Dooley C, Hackstadt T. Selective fragmentation of the trans-Golgi apparatus by Rickettsia rickettsii. PLoS Pathog 2020; 16:e1008582. [PMID: 32421751 PMCID: PMC7259798 DOI: 10.1371/journal.ppat.1008582] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/29/2020] [Accepted: 04/29/2020] [Indexed: 12/15/2022] Open
Abstract
Fragmentation of the Golgi apparatus is observed during a number of physiological processes including mitosis and apoptosis, but also occurs in pathological states such as neurodegenerative diseases and some infectious diseases. Here we show that highly virulent strains of Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever, induce selective fragmentation of the trans-Golgi network (TGN) soon after infection of host cells by secretion of the effector protein Rickettsial Ankyrin Repeat Protein 2 (RARP2). Remarkably, this fragmentation is pronounced for the trans-Golgi network but the cis-Golgi remains largely intact and appropriately localized. Thus R. rickettsii targets specifically the TGN and not the entire Golgi apparatus. Dispersal of the TGN is mediated by the secreted effector protein RARP2, a recently identified type IV secreted effector that is a member of the clan CD cysteine proteases. Site-directed mutagenesis of a predicted cysteine protease active site in RARP2 prevents TGN disruption. General protein transport to the cell surface is severely impacted in cells infected with virulent strains of R. rickettsii. These findings suggest a novel manipulation of cellular organization by an obligate intracellular bacterium to determine interactions with the host cell.
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Affiliation(s)
- Karin Aistleitner
- Host-Parasite Interactions Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - Tina Clark
- Host-Parasite Interactions Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - Cheryl Dooley
- Host-Parasite Interactions Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
| | - Ted Hackstadt
- Host-Parasite Interactions Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, Montana, United States of America
- * E-mail:
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Daniels MJD, Brough D. Unconventional Pathways of Secretion Contribute to Inflammation. Int J Mol Sci 2017; 18:E102. [PMID: 28067797 PMCID: PMC5297736 DOI: 10.3390/ijms18010102] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/16/2016] [Accepted: 12/30/2016] [Indexed: 12/13/2022] Open
Abstract
In the conventional pathway of protein secretion, leader sequence-containing proteins leave the cell following processing through the endoplasmic reticulum (ER) and Golgi body. However, leaderless proteins also enter the extracellular space through mechanisms collectively known as unconventional secretion. Unconventionally secreted proteins often have vital roles in cell and organism function such as inflammation. Amongst the best-studied inflammatory unconventionally secreted proteins are interleukin (IL)-1β, IL-1α, IL-33 and high-mobility group box 1 (HMGB1). In this review we discuss the current understanding of the unconventional secretion of these proteins and highlight future areas of research such as the role of nuclear localisation.
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Affiliation(s)
- Michael J D Daniels
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, AV Hill Building, Oxford Road, Manchester M13 9PT, UK.
| | - David Brough
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, AV Hill Building, Oxford Road, Manchester M13 9PT, UK.
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Phosphorylation of Golgi Peripheral Membrane Protein Grasp65 Is an Integral Step in the Formation of the Human Cytomegalovirus Cytoplasmic Assembly Compartment. mBio 2016; 7:mBio.01554-16. [PMID: 27703074 PMCID: PMC5050342 DOI: 10.1128/mbio.01554-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Human cytomegalovirus (HCMV) is the largest member of the Herpesviridae and represents a significant cause of disease. During virus replication, HCMV alters cellular functions to facilitate its replication, including significant reorganization of the secretory and endocytic pathways of the infected cell. A defining morphologic change of the infected cell is the formation of a membranous structure in the cytoplasm that is designated the virion assembly compartment (AC), which consists of virion structural proteins surrounded by cellular membranes. The loss of normal Golgi compartment morphology and its relocalization from a juxtanuclear ribbonlike structure to a series of concentric rings on the periphery of the AC represents a readily recognized reorganization of cellular membranes in the HCMV-infected cell. Although trafficking of viral proteins to this compartment is required for the assembly of infectious virions, the functional significance of the reorganization of intracellular membranes like the Golgi membranes into the AC in the assembly of infectious virus remains understudied. In this study, we determined that Golgi membrane ribbon fragmentation increased during the early cytoplasmic phase of virion assembly and that Golgi membrane fragmentation in infected cells was dependent on the phosphorylation of an integral cis-Golgi protein, Grasp65. Inhibition of Golgi membrane fragmentation and of its reorganization into the AC resulted in decreased production of infectious particles and alteration of the incorporation of an essential protein into the envelope of the mature virion. These results demonstrated the complexity of the virus-host cell interactions required for efficient assembly of this large DNA virus. The human cytomegalovirus (HCMV)-induced reorganization of intracellular membranes that is required for the formation of the viral assembly compartment (AC) has been an area of study over the last 20 years. The significance of this virus-induced structure has been evinced by the results of several studies which showed that relocalization of viral proteins to the AC was required for efficient assembly of infectious virus. In this study, we have identified a mechanism for the fragmentation of the Golgi ribbon in the infected cell en route to AC morphogenesis. Identification of this fundamental process during HCMV replication allowed us to propose that the functional role of Golgi membrane reorganization during HCMV infection was the concentration of viral structural proteins and subviral structures into a single intracellular compartment in order to facilitate efficient protein-protein interactions and the virion protein trafficking required for the assembly of this large and structurally complex virus.
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Li X, Niu Y, Cheng M, Chi X, Liu X, Yang W. AP1S3 is required for hepatitis C virus infection by stabilizing E2 protein. Antiviral Res 2016; 131:26-34. [PMID: 27079945 DOI: 10.1016/j.antiviral.2016.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 04/05/2016] [Accepted: 04/08/2016] [Indexed: 10/22/2022]
Abstract
Hepatitis C virus (HCV) infects 130 million people worldwide and is a leading cause of liver cirrhosis, end-stage liver disease and hepatocellular carcinoma. The interactions between viral elements and host factors play critical role on HCV invade, replication and release. Here, we identified adaptor protein complex 1 sigma 3 subunit (AP1S3) as a dependency factor for the efficient HCV infection in hepatoma cells. AP1S3 silencing in cultivated Huh7.5.1 cells significantly reduced the production of HCV progeny particles. Immunoprecipitation analysis revealed that AP1S3 interacted with the HCV E2 protein. With this interaction, AP1S3 could protect HCV E2 from ubiquitin-mediated proteasomal degradation. Using in vivo ubiquitylation assay, we identified that E6-Associated Protein (E6AP) was associated with HCV E2. In addition, treatment with synthetic peptide that contains the AP1S3-recognized motif inhibited HCV infection in Huh7.5.1 cells. Our data reveal AP1 as a novel host network that is required by viruses during infection and provides a potential target for developing broad-spectrum anti-virus strategies.
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Affiliation(s)
- Xiang Li
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100176, China
| | - Yuqiang Niu
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100176, China
| | - Min Cheng
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100176, China
| | - Xiaojing Chi
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100176, China
| | - Xiuying Liu
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100176, China
| | - Wei Yang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100176, China.
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Chen Y, Xia Z, Wang L, Yu Y, Liu P, Song E, Xu T. An efficient two-step subcellular fractionation method for the enrichment of insulin granules from INS-1 cells. BIOPHYSICS REPORTS 2015; 1:34-40. [PMID: 26942217 PMCID: PMC4762126 DOI: 10.1007/s41048-015-0008-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 07/03/2015] [Indexed: 10/25/2022] Open
Abstract
Insulin is one of the key regulators for blood glucose homeostasis. More than 99% of insulin is secreted from the pancreatic β-cells. Within each β-cell, insulin is packaged and processed in insulin secretary granules (ISGs) before its exocytosis. Insulin secretion is a complicated but well-organized dynamic process that includes the budding of immature ISGs (iISGs) from the trans-Golgi network, iISG maturation, and mature ISG (mISG) fusion with plasma membrane. However, the molecular mechanisms involved in this process are largely unknown. It is therefore crucial to separate and enrich iISGs and mISGs before determining their distinct characteristics and protein contents. Here, we developed an efficient two-step subcellular fractionation method for the enrichment of iISGs and mISGs from INS-1 cells: OptiPrep gradient purification followed by Percoll solution purification. We demonstrated that by using this method, iISGs and mISGs can be successfully distinguished and enriched. This method can be easily adapted to investigate SGs in other cells or tissues, thereby providing a useful tool for elucidating the mechanisms of granule maturation and secretion.
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Affiliation(s)
- Yan Chen
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Zhiping Xia
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Lifen Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yong Yu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Eli Song
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Tao Xu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
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Abstract
Viruses employ a variety of strategies to usurp and control cellular activities through the orchestrated recruitment of macromolecules to specific cytoplasmic or nuclear compartments. Formation of such specialized virus-induced cellular microenvironments, which have been termed viroplasms, virus factories, or virus replication centers, complexes, or compartments, depends on molecular interactions between viral and cellular factors that participate in viral genome expression and replication and are in some cases associated with sites of virion assembly. These virus-induced compartments function not only to recruit and concentrate factors required for essential steps of the viral replication cycle but also to control the cellular mechanisms of antiviral defense. In this review, we summarize characteristic features of viral replication compartments from different virus families and discuss similarities in the viral and cellular activities that are associated with their assembly and the functions they facilitate for viral replication.
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Netherton CL, Wileman TE. African swine fever virus organelle rearrangements. Virus Res 2013; 173:76-86. [PMID: 23291273 DOI: 10.1016/j.virusres.2012.12.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 11/30/2012] [Accepted: 12/03/2012] [Indexed: 11/28/2022]
Abstract
Like most viruses African swine fever virus (ASFV) subsumes the host cell apparatus in order to facilitate its replication. ASFV replication is a highly orchestrated process with a least four stages of transcription, immediate-early, early, intermediate and late. As the infective cycle progresses through these stages most if not all of the organelles that comprise a nucleated cell are modified, adapted or in some cases destroyed. The entry of the virus is receptor-mediated, but the precise mechanism of endocytosis is a matter of keen, current debate. Once ASFV has exited from the endosomal-lysosomal complex the virus life-cycle enters into an intimate relationship with the microtubular network. Genome replication is believed to be initiated within the nucleus and ASFV infection completely reorders the structure of this organelle. The majority of replication and assembly occurs in discrete, perinuclear regions of the cell called virus factories and finally progeny virions are transported to the plasma membrane along microtubules where they bud out or are propelled away along actin projections to infect new cells. The generation of ASFV replication sites induces profound reorganisation of the organelles that comprise the secretory pathway and may contribute to the induction of cellular stress responses that ASFV modulates. The level of organisation and complexity of virus factories are not dissimilar to those seen in cellular organelles. Like their cellular counterparts the formation of virus factories, as well as virus entry and exit, are dependent on the various components of the cytoskeleton. This review will summarise these rearrangements, the viral proteins involved and their functional consequences.
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Affiliation(s)
- Christopher L Netherton
- Vaccinology Group, The Pirbright Institute, Pirbright, Woking, Surrey GU24 0NF, United Kingdom.
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12
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Burrage TG. African swine fever virus infection in Ornithodoros ticks. Virus Res 2012; 173:131-9. [PMID: 23085123 DOI: 10.1016/j.virusres.2012.10.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Revised: 09/29/2012] [Accepted: 10/07/2012] [Indexed: 01/08/2023]
Abstract
African swine fever virus (ASFV) is an arbovirus which is vectored by soft ticks of the Ornithodoros spp. and in the sylvatic cycle infects wart hogs and bush pigs. ASFV infection of domestic swine causes a high mortality disease. On the other hand, ASFV infection of the tick can result in a high-titered and persistent infection depending upon the ASFV isolate and the tick combination. Recently, morphological, classical virology (titration) and recombinant ASFV have been used to study the cellular, molecular and genetic interactions that occur between ASFV and its host tick.
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Affiliation(s)
- Thomas G Burrage
- Department of Homeland Security, S & T, Targeted Advance Development, Virus, Cellular and Molecular Imaging, PO Box 848, Plum Island Animal Disease Center, Greenport, NY 11944, United States.
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Abstract
African swine fever virus (ASFV) is a large DNA virus that enters host cells after receptor-mediated endocytosis and depends on acidic cellular compartments for productive infection. The exact cellular mechanism, however, is largely unknown. In order to dissect ASFV entry, we have analyzed the major endocytic routes using specific inhibitors and dominant negative mutants and analyzed the consequences for ASFV entry into host cells. Our results indicate that ASFV entry into host cells takes place by clathrin-mediated endocytosis which requires dynamin GTPase activity. Also, the clathrin-coated pit component Eps15 was identified as a relevant cellular factor during infection. The presence of cholesterol in cellular membranes, but not lipid rafts or caveolae, was found to be essential for a productive ASFV infection. In contrast, inhibitors of the Na(+)/H(+) ion channels and actin polymerization inhibition did not significantly modify ASFV infection, suggesting that macropinocytosis does not represent the main entry route for ASFV. These results suggest a dynamin-dependent and clathrin-mediated endocytic pathway of ASFV entry for the cell types and viral strains analyzed.
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Abstract
Summary: The interface between successful pathogens and their hosts is often a tenuous balance. In acute viral infections, this balance involves induction and inhibition of innate responses. Foot‐and‐mouth disease virus (FMDV) is considered one of the most contagious viruses known and is characterized by rapid induction of clinical disease in cloven hoofed animals exposed to infection. Viral shedding is extensive before the equally rapid resolution of acute disease. This positive strand RNA virus is an extremely successful pathogen, due in part to the ability to interrupt the innate immune response. Previous reviews have described the inhibition of cellular innate responses in the infected cell both in vitro and in vivo. Here, we present a review of virus inhibition of cells that are a source of antiviral function in swine. Particularly in the case of dendritic cells and natural killer cells, the virus has evolved mechanisms to interrupt the normal function of these important mediators of innate function, even though these cells are not infected by the virus. Understanding how this virus subverts the innate response will provide valuable information for the development of rapidly acting biotherapeutics to use in response to an outbreak of FMDV.
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Affiliation(s)
- William T Golde
- Plum Island Animal Disease Center, ARS, USDA, Greenport, NY 11944-0848, USA.
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15
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Abstract
African swine fever virus (ASFV) is a large, intracytoplasmically-replicating DNA arbovirus and the sole member of the family Asfarviridae. It is the etiologic agent of a highly lethal hemorrhagic disease of domestic swine and therefore extensively studied to elucidate the structures, genes, and mechanisms affecting viral replication in the host, virus-host interactions, and viral virulence. Increasingly apparent is the complexity with which ASFV replicates and interacts with the host cell during infection. ASFV encodes novel genes involved in host immune response modulation, viral virulence for domestic swine, and in the ability of ASFV to replicate and spread in its tick vector. The unique nature of ASFV has contributed to a broader understanding of DNA virus/host interactions.
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Affiliation(s)
- E R Tulman
- Department of Pathobiology and Veterinary Science, Center of Excellence for Vaccine Research, University of Connecticut, Storrs 06269, USA.
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Netherton C, Moffat K, Brooks E, Wileman T. A guide to viral inclusions, membrane rearrangements, factories, and viroplasm produced during virus replication. Adv Virus Res 2007; 70:101-82. [PMID: 17765705 PMCID: PMC7112299 DOI: 10.1016/s0065-3527(07)70004-0] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Virus replication can cause extensive rearrangement of host cell cytoskeletal and membrane compartments leading to the “cytopathic effect” that has been the hallmark of virus infection in tissue culture for many years. Recent studies are beginning to redefine these signs of viral infection in terms of specific effects of viruses on cellular processes. In this chapter, these concepts have been illustrated by describing the replication sites produced by many different viruses. In many cases, the cellular rearrangements caused during virus infection lead to the construction of sophisticated platforms in the cell that concentrate replicase proteins, virus genomes, and host proteins required for replication, and thereby increase the efficiency of replication. Interestingly, these same structures, called virus factories, virus inclusions, or virosomes, can recruit host components that are associated with cellular defences against infection and cell stress. It is possible that cellular defence pathways can be subverted by viruses to generate sites of replication. The recruitment of cellular membranes and cytoskeleton to generate virus replication sites can also benefit viruses in other ways. Disruption of cellular membranes can, for example, slow the transport of immunomodulatory proteins to the surface of infected cells and protect against innate and acquired immune responses, and rearrangements to cytoskeleton can facilitate virus release.
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Affiliation(s)
- Christopher Netherton
- Vaccinology Group, Pirbright Laboratories, Institute for Animal Health, Surrey, United Kingdom
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Netherton CL, McCrossan MC, Denyer M, Ponnambalam S, Armstrong J, Takamatsu HH, Wileman TE. African swine fever virus causes microtubule-dependent dispersal of the trans-golgi network and slows delivery of membrane protein to the plasma membrane. J Virol 2006; 80:11385-92. [PMID: 16956944 PMCID: PMC1642160 DOI: 10.1128/jvi.00439-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Accepted: 08/28/2006] [Indexed: 11/20/2022] Open
Abstract
Viral interference with secretory cargo is a common mechanism for pathogen immune evasion. Selective down regulation of critical immune system molecules such as major histocompatibility complex (MHC) proteins enables pathogens to mask themselves from their host. African swine fever virus (ASFV) disrupts the trans-Golgi network (TGN) by altering the localization of TGN46, an organelle marker for the distal secretory pathway. Reorganization of membrane transport components may provide a mechanism whereby ASFV can disrupt the correct secretion and/or cell surface expression of host proteins. In the study reported here, we used the tsO45 temperature-sensitive mutant of the G protein of vesicular stomatitis virus to show that ASFV significantly reduces the rate at which the protein is delivered to the plasma membrane. This is linked to a general reorganization of the secretory pathway during infection and a specific, microtubule-dependent disruption of structural components of the TGN. Golgin p230 and TGN46 are separated into distinct vesicles, whereupon TGN46 is depleted. These data suggest that disruption of the TGN by ASFV can slow membrane traffic during viral infection. This may be functionally important because infection of macrophages with virulent isolates of ASFV increased the expression of MHC class I genes, but there was no parallel increase in MHC class I molecule delivery to the plasma membrane.
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Affiliation(s)
- Christopher L Netherton
- Pirbright Laboratory, Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, United Kingdom.
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Jouvenet N, Wileman T. African swine fever virus infection disrupts centrosome assembly and function. J Gen Virol 2005; 86:589-594. [PMID: 15722518 DOI: 10.1099/vir.0.80623-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
African swine fever virus (ASFV) is a large, enveloped DNA virus that assembles in perinuclear sites located close to the centrosome. It is reported here that the microtubule network becomes disorganized soon after the onset of viral DNA replication and formation of assembly sites. ASFV infection resulted in loss of gamma-tubulin and pericentrin at the centrosome; this was due to protein relocalization, but not degradation. ASFV infection also inhibited the ability of the centrosome to nucleate microtubules. The reorganization of microtubules seen in ASFV-infected cells may therefore be mediated by gamma-tubulin and pericentrin redistribution, and consequent disruption of centrosome assembly and function.
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Affiliation(s)
- Nolwenn Jouvenet
- Department of Immunology and Pathology, Pirbright Laboratories, Institute for Animal Health, Ash Road, Woking, Surrey GU24 0NF, UK
| | - Thomas Wileman
- Department of Immunology and Pathology, Pirbright Laboratories, Institute for Animal Health, Ash Road, Woking, Surrey GU24 0NF, UK
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Jouvenet N, Monaghan P, Way M, Wileman T. Transport of African swine fever virus from assembly sites to the plasma membrane is dependent on microtubules and conventional kinesin. J Virol 2004; 78:7990-8001. [PMID: 15254171 PMCID: PMC446130 DOI: 10.1128/jvi.78.15.7990-8001.2004] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
African swine fever virus (ASFV) is a large DNA virus that assembles in perinuclear viral factories located close to the microtubule organizing center. In this study, we have investigated the mechanism by which ASFV reaches the cell surface from the site of assembly. Immunofluorescence microscopy revealed that at 16 h postinfection, mature virions were aligned along microtubules. Furthermore, virus movement to the cell periphery was inhibited when microtubules were depolymerized by nocodazole. In addition, ASFV infection resulted in the increased acetylation of microtubules as well as their protection against depolymerization by nocodazole. Immunofluorescence microscopy showed that conventional kinesin was recruited to virus factories and to a large fraction of virus particles in the cytoplasm. Consistent with a role for conventional kinesin during ASFV egress to the cell periphery, overexpression of the cargo-binding domain of the kinesin light chain severely inhibited the movement of particles to the plasma membrane. Based on our observations, we propose that ASFV is recognized as cargo by conventional kinesin and uses this plus-end microtubule motor to move from perinuclear assembly sites to the plasma membrane.
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Affiliation(s)
- Nolwenn Jouvenet
- Department of Immunology and Pathology, Institute for Animal Health, Surrey GU24 0NF, United Kingdom
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Netherton C, Rouiller I, Wileman T. The subcellular distribution of multigene family 110 proteins of African swine fever virus is determined by differences in C-terminal KDEL endoplasmic reticulum retention motifs. J Virol 2004; 78:3710-21. [PMID: 15016891 PMCID: PMC371041 DOI: 10.1128/jvi.78.7.3710-3721.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
African swine fever virus (ASFV) is a large double-stranded DNA virus that replicates in discrete areas in the cytosol of infected cells called viral factories. Recent studies have shown that assembling virions acquire their internal envelopes through enwrapment by membranes derived from the endoplasmic reticulum (ER). However, the mechanisms that underlie the formation of viral factories and progenitor viral membranes are as yet unclear. Analysis of the published genome of the virus revealed a conserved multigene family that encodes proteins with hydrophobic signal sequences, indicating possible translocation into the ER lumen. Strikingly, two of these genes, XP124L and Y118L, encoded proteins with KDEL-like ER retention motifs. Analysis of XP124L and Y118L gene product by biochemical and immunofluorescence techniques showed that the proteins were localized to pre-Golgi compartments and that the KEDL motif at the C terminus of pXP124L was functional. XP124L expression, in the absence of other ASFV genes, had a dramatic effect on the contents of the ER that was dependent precisely on the C-terminal sequence KEDL. The normal subcellular distribution of a number of proteins resident to this important, cellular organelle was drastically altered in cells expressing wild-type XP124L gene product. PXP124L formed unusual perinuclear structures that contained resident ER proteins, as well as proteins of the ER-Golgi intermediate compartment. The data presented here hint at a role for MGF110 gene product in preparing the ER for its role in viral morphogenesis; this and other potential functions are discussed.
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Affiliation(s)
- Christopher Netherton
- Division of Immunology, Pirbright Laboratory, Institute for Animal Health, Pirbright, Surrey GU24 0NF, United Kingdom
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Kay-Jackson PC, Goatley LC, Cox L, Miskin JE, Parkhouse RME, Wienands J, Dixon LK. The CD2v protein of African swine fever virus interacts with the actin-binding adaptor protein SH3P7. J Gen Virol 2004; 85:119-130. [PMID: 14718626 DOI: 10.1099/vir.0.19435-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The predicted extracellular domain of the CD2v protein of African swine fever virus (ASFV) shares significant similarity to that of the CD2 protein in T cells but has a unique cytoplasmic domain of unknown function. Here we have shown that CD2v is expressed as a glycoprotein of approximately 105 kDa in ASFV-infected cells. In the absence of an extracellular ligand, the majority of CD2v appears to localize to perinuclear membrane compartments. Furthermore, we have shown using the yeast two-hybrid system and by direct binding studies that the cytoplasmic tail of CD2v binds to the cytoplasmic adaptor protein SH3P7 (mAbp1, HIP55), which has been reported to be involved in diverse cellular functions such as vesicle transport and signal transduction. A cDNA clone encoding a variant form of SH3P7 could also be identified and was found to be expressed in a wide range of porcine tissues. Deletion mutagenesis identified proline-rich repeats of sequence PPPKPC in the ASFV CD2v protein to be necessary and sufficient for binding to the SH3 domain of SH3P7. In ASFV-infected cells, CD2v and SH3P7 co-localized in areas surrounding the perinuclear virus factories. These areas also stained with an antibody that recognizes a Golgi network protein, indicating that they contained membranes derived from the Golgi network. Our data provide a first molecular basis for the understanding of the immunomodulatory functions of CD2v in ASFV-infected animals.
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Affiliation(s)
- P C Kay-Jackson
- Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK
| | - L C Goatley
- Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK
| | - L Cox
- Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK
| | - J E Miskin
- Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK
| | | | - J Wienands
- Department of Biochemistry and Molecular Immunology, University of Bielefeld, D-33615 Bielefeld, Germany
| | - L K Dixon
- Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK
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Gerrard SR, Rollin PE, Nichol ST. Bidirectional infection and release of Rift Valley fever virus in polarized epithelial cells. Virology 2002; 301:226-35. [PMID: 12359425 DOI: 10.1006/viro.2002.1588] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rift Valley Fever (RVF) virus is an arbovirus and is responsible for large outbreaks of disease predominantly in sub-Saharan Africa. However, several aspects of RVF virus transmission, such as high viremia, multiple vector species, and broad host range, result in a pathogen with high likelihood of geographic spread. RVF virus infection in humans and livestock is characterized by broad dissemination of RVF virus antigens throughout the body. We sought insight into the high pathogenicity and broad tropism of this virus through a characterization of its interaction with polarized epithelial cells. Our results indicate that infection and release of RVF virus in polarized epithelial cells occurs at both apical and basolateral membranes and hence is bidirectional. Furthermore, our results indicate that RVF virus causes disruptions in both the microfilament and the microtubule networks. These disruptions may provide a mechanism for bidirectional release of RVF virions.
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Affiliation(s)
- Sonja R Gerrard
- Special Pathogens Branch, Division of Viral and Rickettsial Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA
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