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Schuchman RM, Vancini R, Piper A, Breuer D, Ribeiro M, Ferreira D, Magliocca J, Emmerich V, Hernandez R, Brown DT. Role of the vacuolar ATPase in the Alphavirus replication cycle. Heliyon 2018; 4:e00701. [PMID: 30094371 PMCID: PMC6074608 DOI: 10.1016/j.heliyon.2018.e00701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 06/07/2018] [Accepted: 07/18/2018] [Indexed: 02/06/2023] Open
Abstract
We have shown that Alphaviruses can enter cells by direct penetration at the plasma membrane (R. Vancini, G. Wang, D. Ferreira, R. Hernandez, and D. Brown, J Virol, 87:4352–4359, 2013). Direct penetration removes the requirement for receptor-mediated endocytosis exposure to low pH and membrane fusion in the process of RNA entry. Endosomal pH as well as the pH of the cell cytoplasm is maintained by the activity of the vacuolar ATPase (V-ATPase). Bafilomycin is a specific inhibitor of V-ATPase. To characterize the roll of the V-ATPase in viral replication we generated a Bafilomycin A1(BAF) resistant mutant of Sindbis virus (BRSV). BRSV produced mature virus and virus RNA in greater amounts than parent virus in BAF-treated cells. Sequence analysis revealed mutations in the E2 glycoprotein, T15I/Y18H, were responsible for the phenotype. These results show that a functional V-ATPase is required for efficient virus RNA synthesis and virus maturation in Alphavirus infection.
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Affiliation(s)
- Ryan M Schuchman
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Ricardo Vancini
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Amanda Piper
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Denitra Breuer
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Mariana Ribeiro
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Davis Ferreira
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA.,Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Joseph Magliocca
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Veronica Emmerich
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Raquel Hernandez
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Dennis T Brown
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
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van Duijl-Richter MKS, Blijleven JS, van Oijen AM, Smit JM. Chikungunya virus fusion properties elucidated by single-particle and bulk approaches. J Gen Virol 2015; 96:2122-2132. [DOI: 10.1099/vir.0.000144] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Mareike K. S. van Duijl-Richter
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
| | - Jelle S. Blijleven
- Centre for Synthetic Biology, Zernike Institute of Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Antoine M. van Oijen
- Centre for Synthetic Biology, Zernike Institute of Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
- School of Chemistry, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Jolanda M. Smit
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
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Abstract
Chikungunya virus (CHIKV) is a rapidly emerging mosquito-borne alphavirus causing millions of infections in the tropical and subtropical regions of the world. CHIKV infection often leads to an acute self-limited febrile illness with debilitating myalgia and arthralgia. A potential long-term complication of CHIKV infection is severe joint pain, which can last for months to years. There are no vaccines or specific therapeutics available to prevent or treat infection. This review describes the critical steps in CHIKV cell entry. We summarize the latest studies on the virus-cell tropism, virus-receptor binding, internalization, membrane fusion and review the molecules and compounds that have been described to interfere with virus cell entry. The aim of the review is to give the reader a state-of-the-art overview on CHIKV cell entry and to provide an outlook on potential new avenues in CHIKV research.
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Replication of alphaviruses: a review on the entry process of alphaviruses into cells. Adv Virol 2011; 2011:249640. [PMID: 22312336 PMCID: PMC3265296 DOI: 10.1155/2011/249640] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 05/03/2011] [Indexed: 02/04/2023] Open
Abstract
Alphaviruses are small, enveloped viruses, ~70 nm in diameter, containing a single-stranded, positive-sense, RNA genome. Viruses belonging to this genus are predominantly arthropod-borne viruses, known to cause disease in humans. Their potential threat to human health was most recently exemplified by the 2005 Chikungunya virus outbreak in La Reunion, highlighting the necessity to understand events in the life-cycle of these medically important human pathogens. The replication and propagation of viruses is dependent on entry into permissive cells. Viral entry is initiated by attachment of virions to cells, leading to internalization, and uncoating to release genetic material for replication and propagation. Studies on alphaviruses have revealed entry via a receptor-mediated, endocytic pathway. In this paper, the different stages of alphavirus entry are examined, with examples from Semliki Forest virus, Sindbis virus, Chikungunya virus, and Venezuelan equine encephalitis virus described.
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Kononchik JP, Vancini R, Brown DT. Alphavirus adsorption to mosquito cells as viewed by freeze fracture immunolabeling. Virology 2011; 415:132-40. [DOI: 10.1016/j.virol.2011.04.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 04/11/2011] [Accepted: 04/22/2011] [Indexed: 12/12/2022]
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Abstract
The study of alphavirus entry has been complicated by an inability to clearly identify a receptor and by experiments which only tangentially and indirectly examine the process, producing results that are difficult to interpret. The mechanism of entry has been widely accepted to be by endocytosis followed by acidification of the endosome resulting in virus membrane-endosome membrane fusion. This mechanism has come under scrutiny as better purification protocols and improved methods of analysis have been brought to the study. Results have been obtained that suggest alphaviruses infect cells directly at the plasma membrane without the involvement of endocytosis, exposure to acid pH, or membrane fusion. In this review we compare the data which support the two models and make the case for an alternative pathway of entry by alphaviruses.
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Abstract
The study of enveloped animal viruses has greatly advanced our understanding of the general properties of membrane fusion and of the specific pathways that viruses use to infect the host cell. The membrane fusion proteins of the alphaviruses and flaviviruses have many similarities in structure and function. As reviewed here, alphaviruses use receptor-mediated endocytic uptake and low pH-triggered membrane fusion to deliver their RNA genomes into the cytoplasm. Recent advances in understanding the biochemistry and structure of the alphavirus membrane fusion protein provide a clearer picture of this fusion reaction, including the protein’s conformational changes during fusion and the identification of key domains. These insights into the alphavirus fusion mechanism suggest new areas for experimental investigation and potential inhibitor strategies for anti-viral therapy.
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Affiliation(s)
- Margaret Kielian
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-718-430-3638; Fax: +1-718-430-8574
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Abstract
Enveloped viruses penetrate the host cells by fusion of the viral envelope with a cellular target membrane. One of the best studied viruses with respect to its penetration and uncoating is the alphavirus Semliki Forest virus that is taken up by endocytosis. The alphavirus membrane glycoprotein E1 harbors a so-called fusion peptide, which is responsible for interaction with the endosomal membrane, leading to fusion. Besides this fusion process, cell infection by alphaviruses is accompanied by membrane permeability changes, thus implying some form of pore across the membrane. However, the ability of E1 protein to form ion pores has not been widely accepted. This review provides an overview of studies that confirm earlier results predicting the formation of a proteinaceous pore by the alphavirus spike proteins. Furthermore, different models to explain this pore formation during virus entry are discussed.
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Affiliation(s)
- Fabian Käsermann
- University of Bern, Department of Chemistry & Biochemistry, Bern, Switzerland and, ZLB Behring AG, Switzerland
| | - Christoph Kempf
- University of Bern, Department of Chemistry & Biochemistry, Bern, Switzerland and, ZLB Behring AG, Switzerland
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Koschinski A, Wengler G, Wengler G, Repp H. Rare earth ions block the ion pores generated by the class II fusion proteins of alphaviruses and allow analysis of the biological functions of these pores. J Gen Virol 2005; 86:3311-3320. [PMID: 16298976 DOI: 10.1099/vir.0.81096-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recently, class II fusion proteins have been identified on the surface of alpha- and flaviviruses. These proteins have two functions besides membrane fusion: they generate an isometric lattice on the viral surface and they form ion-permeable pores at low pH. An attempt was made to identify inhibitors for the ion pores generated by the fusion proteins of the alphaviruses Semliki Forest virus and Sindbis virus. These pores can be detected and analysed in three situations: (i) in the target membrane during virus entry, by performing patch-clamp measurements of membrane currents; (ii) in the virus particle, by studying the entry of propidium iodide; and (iii) in the plasma membrane of infected cells, by Fura-2 fluorescence imaging of Ca2+ entry into infected cells. It is shown here that, at a concentration of 0·1 mM, rare earth ions block the ion permeability of alphavirus ion pores in all three situations. Even at a concentration of 0·5 mM, these ions do not block formation of the viral fusion pore, as they do not inhibit entry or multiplication of alphaviruses. The data indicate that ions flow through the ion pores into the virus particle in the endosome and from the endosome into the cytoplasm after fusion of the viral envelope with the endosomal membrane. These ion flows, however, are not necessary for productive infection. The possibility that the ability of class II fusion proteins to form ion-permeable pores reflects their origin from protein toxins that form ion-permeable pores, and that entry via class II fusion proteins may resemble the entry of non-enveloped viruses, is discussed.
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Affiliation(s)
- Andreas Koschinski
- Rudolf-Buchheim-Institut für Pharmakologie, Justus-Liebig-Universität, D-35392 Giessen, Germany
| | - Gerd Wengler
- Institut für Virologie, Fachbereich Veterinärmedizin, Justus-Liebig-Universität, D-35392 Giessen, Germany
| | - Gisela Wengler
- Institut für Virologie, Fachbereich Veterinärmedizin, Justus-Liebig-Universität, D-35392 Giessen, Germany
| | - Holger Repp
- Rudolf-Buchheim-Institut für Pharmakologie, Justus-Liebig-Universität, D-35392 Giessen, Germany
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