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Gebert JT, Scribano F, Engevik KA, Perry JL, Hyser JM. Gastrointestinal organoids in the study of viral infections. Am J Physiol Gastrointest Liver Physiol 2023; 324:G51-G59. [PMID: 36414538 PMCID: PMC9799139 DOI: 10.1152/ajpgi.00152.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 11/04/2022] [Accepted: 11/14/2022] [Indexed: 11/24/2022]
Abstract
Viruses are among the most prevalent enteric pathogens. Although virologists historically relied on cell lines and animal models, human intestinal organoids (HIOs) continue to grow in popularity. HIOs are nontransformed, stem cell-derived, ex vivo cell cultures that maintain the cell type diversity of the intestinal epithelium. They offer higher throughput than standard animal models while more accurately mimicking the native tissue of infection than transformed cell lines. Here, we review recent literature that highlights virological advances facilitated by HIOs. We discuss the variations and limitations of HIOs, how HIOs have allowed for the cultivation of previously uncultivatable viruses, and how they have offered insight into tropism, entry, replication kinetics, and host-pathogen interactions. In each case, we discuss exemplary viruses and archetypal studies. We discuss how the speed and flexibility of HIO-based studies contributed to our knowledge of SARS-CoV-2 and antiviral therapeutics. Finally, we discuss the current limitations of HIOs and future directions to overcome these.
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Affiliation(s)
- J Thomas Gebert
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas
| | - Francesca Scribano
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas
| | - Kristen A Engevik
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas
| | - Jacob L Perry
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas
| | - Joseph M Hyser
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas
- Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas
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2
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Russell T, Gangotia D, Barry G. Assessing the potential of repurposing ion channel inhibitors to treat emerging viral diseases and the role of this host factor in virus replication. Biomed Pharmacother 2022; 156:113850. [DOI: 10.1016/j.biopha.2022.113850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/25/2022] [Accepted: 10/06/2022] [Indexed: 12/03/2022] Open
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3
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Qu Y, Sun Y, Yang Z, Ding C. Calcium Ions Signaling: Targets for Attack and Utilization by Viruses. Front Microbiol 2022; 13:889374. [PMID: 35859744 PMCID: PMC9289559 DOI: 10.3389/fmicb.2022.889374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 06/15/2022] [Indexed: 12/25/2022] Open
Abstract
Calcium, as a second intracellular messenger, participate in various physiological and biochemical processes, including cell growth and proliferation, energy metabolism, information transfer, cell death, and immune response. Ca2+ channels or pumps in plasma and organelle membranes and Ca2+-related proteins maintain Ca2+ homeostasis by regulating Ca2+ inflow, outflow and buffering to avoid any adverse effects caused by Ca2+ overload or depletion. Thus, Ca2+ signaling also provides a target for virus invasion, replication, proliferation and release. After hijacking the host cell, viruses exploit Ca2+ signaling to regulate apoptosis and resist host immunity to establish persistent infection. In this review, we discuss cellular Ca2+ signaling and channels, interaction of calcium-associated proteins with viruses, and host cell fate, as well as the role of Ca2+ in cell death and antiviral response during viral infection.
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Affiliation(s)
- Yang Qu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, China
| | - Yingjie Sun
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, China
| | - Zengqi Yang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
- Zengqi Yang,
| | - Chan Ding
- Department of Avian Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
- *Correspondence: Chan Ding,
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Melnik LI, Garry RF. Enterotoxigenic Escherichia coli Heat-Stable Toxin and Ebola Virus Delta Peptide: Similarities and Differences. Pathogens 2022; 11:pathogens11020170. [PMID: 35215114 PMCID: PMC8878840 DOI: 10.3390/pathogens11020170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/22/2022] [Accepted: 01/24/2022] [Indexed: 01/27/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) STb toxin exhibits striking structural similarity to Ebola virus (EBOV) delta peptide. Both ETEC and EBOV delta peptide are enterotoxins. Comparison of the structural and functional similarities and differences of these two toxins illuminates features that are important in induction of pathogenesis by a bacterial and viral pathogen.
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Affiliation(s)
- Lilia I. Melnik
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA;
- Viral Hemorrhagic Fever Consortium, New Orleans, LA 70112, USA
- Correspondence: ; Tel.: +1-(504)988-3818
| | - Robert F. Garry
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA;
- Viral Hemorrhagic Fever Consortium, New Orleans, LA 70112, USA
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Melnik LI, Guha S, Ghimire J, Smither AR, Beddingfield BJ, Hoffmann AR, Sun L, Ungerleider NA, Baddoo MC, Flemington EK, Gallaher WR, Wimley WC, Garry RF. Ebola virus delta peptide is an enterotoxin. Cell Rep 2022; 38:110172. [PMID: 34986351 DOI: 10.1016/j.celrep.2021.110172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/27/2021] [Accepted: 12/03/2021] [Indexed: 12/21/2022] Open
Abstract
During the 2013-2016 West African (WA) Ebola virus (EBOV) outbreak, severe gastrointestinal symptoms were common in patients and associated with poor outcome. Delta peptide is a conserved product of post-translational processing of the abundant EBOV soluble glycoprotein (sGP). The murine ligated ileal loop model was used to demonstrate that delta peptide is a potent enterotoxin. Dramatic intestinal fluid accumulation follows injection of biologically relevant amounts of delta peptide into ileal loops, along with gross alteration of villous architecture and loss of goblet cells. Transcriptomic analyses show that delta peptide triggers damage response and cell survival pathways and downregulates expression of transporters and exchangers. Induction of diarrhea by delta peptide occurs via cellular damage and regulation of genes that encode proteins involved in fluid secretion. While distinct differences exist between the ileal loop murine model and EBOV infection in humans, these results suggest that delta peptide may contribute to EBOV-induced gastrointestinal pathology.
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Affiliation(s)
- Lilia I Melnik
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Shantanu Guha
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Jenisha Ghimire
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Allison R Smither
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Brandon J Beddingfield
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Andrew R Hoffmann
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Leisheng Sun
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | | | - Melody C Baddoo
- Tulane Cancer Center, Tulane University, New Orleans, LA 70112, USA
| | | | - William R Gallaher
- Department of Microbiology, Immunology and Parasitology, LSU Health Sciences Center, New Orleans, LA 70112, USA; Mockingbird Nature Research Group, Pearl River, LA 70452, USA
| | - William C Wimley
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
| | - Robert F Garry
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA; Zalgen Labs, Germantown, MD 20876, USA.
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Saurav S, Tanwar J, Ahuja K, Motiani RK. Dysregulation of host cell calcium signaling during viral infections: Emerging paradigm with high clinical relevance. Mol Aspects Med 2021; 81:101004. [PMID: 34304899 PMCID: PMC8299155 DOI: 10.1016/j.mam.2021.101004] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/18/2021] [Accepted: 07/16/2021] [Indexed: 12/22/2022]
Abstract
Viral infections are one of the leading causes of human illness. Viruses take over host cell signaling cascades for their replication and infection. Calcium (Ca2+) is a versatile and ubiquitous second messenger that modulates plethora of cellular functions. In last two decades, a critical role of host cell Ca2+ signaling in modulating viral infections has emerged. Furthermore, recent literature clearly implicates a vital role for the organellar Ca2+ dynamics (influx and efflux across organelles) in regulating virus entry, replication and severity of the infection. Therefore, it is not surprising that a number of viral infections including current SARS-CoV-2 driven COVID-19 pandemic are associated with dysregulated Ca2+ homeostasis. The focus of this review is to first discuss the role of host cell Ca2+ signaling in viral entry, replication and egress. We further deliberate on emerging literature demonstrating hijacking of the host cell Ca2+ dynamics by viruses. In particular, a variety of viruses including SARS-CoV-2 modulate lysosomal and cytosolic Ca2+ signaling for host cell entry and replication. Moreover, we delve into the recent studies, which have demonstrated the potential of several FDA-approved drugs targeting Ca2+ handling machinery in inhibiting viral infections. Importantly, we discuss the prospective of targeting intracellular Ca2+ signaling for better management and treatment of viral pathogenesis including COVID-19. Finally, we highlight the key outstanding questions in the field that demand critical and timely attention.
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Affiliation(s)
- Suman Saurav
- Laboratory of Calciomics and Systemic Pathophysiology, Regional Centre for Biotechnology (RCB), Faridabad-121001, Delhi-NCR, India
| | - Jyoti Tanwar
- CSIR-Institute of Genomics and Integrative Biology (IGIB), New Delhi-110025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Kriti Ahuja
- Laboratory of Calciomics and Systemic Pathophysiology, Regional Centre for Biotechnology (RCB), Faridabad-121001, Delhi-NCR, India
| | - Rajender K Motiani
- Laboratory of Calciomics and Systemic Pathophysiology, Regional Centre for Biotechnology (RCB), Faridabad-121001, Delhi-NCR, India.
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Patra U, Mukhopadhyay U, Mukherjee A, Dutta S, Chawla-Sarkar M. Treading a HOSTile path: Mapping the dynamic landscape of host cell-rotavirus interactions to explore novel host-directed curative dimensions. Virulence 2021; 12:1022-1062. [PMID: 33818275 PMCID: PMC8023246 DOI: 10.1080/21505594.2021.1903198] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Viruses are intracellular pathogens and are dependent on host cellular resources to carry out their cycles of perpetuation. Obtaining an integrative view of host-virus interaction is of utmost importance to understand the complex and dynamic interplay between viral components and host machineries. Besides its obvious scholarly significance, a comprehensive host-virus interaction profile also provides a platform where from host determinants of pro-viral and antiviral importance can be identified and further be subjected to therapeutic intervention. Therefore, adjunct to conventional methods of prophylactic vaccination and virus-directed antivirals, this host-targeted antiviral approach holds promising therapeutic potential. In this review, we present a comprehensive landscape of host cellular reprogramming in response to infection with rotavirus (RV) which causes profuse watery diarrhea in neonates and infants. In addition, an emphasis is given on how host determinants are either usurped or subverted by RV in course of infection and how therapeutic manipulation of specific host factors can effectively modulate the RV life cycle.
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Affiliation(s)
- Upayan Patra
- Division of Virology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Urbi Mukhopadhyay
- Division of Virology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Arpita Mukherjee
- Division of Virology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Shanta Dutta
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
| | - Mamta Chawla-Sarkar
- Division of Virology, National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, India
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Matsumoto T, Sunada K, Nagai T, Isobe T, Matsushita S, Ishiguro H, Nakajima A. Effects of cerium and tungsten substitution on antiviral and antibacterial properties of lanthanum molybdate. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 117:111323. [PMID: 32919679 PMCID: PMC7402209 DOI: 10.1016/j.msec.2020.111323] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/20/2020] [Accepted: 07/30/2020] [Indexed: 11/26/2022]
Abstract
Powders of cerium (Ce)-substituted and tungsten (W)-substituted La2Mo2O9 (LMO) were prepared using polymerizable complex method. Their antiviral and antibacterial performances were then evaluated using bacteriophage Qβ, bacteriophage Φ6, Escherichia coli, and Staphylococcus aureus. The obtained powders, which were almost single-phase, exhibited both antiviral and antibacterial properties. Effects of dissolved ions on their antiviral activity against bacteriophage Qβ were remarkable. A certain contribution of direct contact to the powder surface was also inferred along with the dissolved ion effect for antiviral activity against bacteriophage Φ6. Dissolved ion effects and pH values suggest that both Mo and W are in the form of polyacids. Antiviral activity against bacteriophage Φ6 was improved by substituting Ce for La in LMO. Similarly to LMO, Ce-substituted LMO exhibited hydrophobicity. Inactivation of alkaline phosphatase enzyme proteins was inferred as one mechanism of the antiviral and antibacterial activities of the obtained powders. Ce and W were partially substituted in La2Mo2O9 (LMO). These powders inactivated E. coli, S. aureus, bacteriophage Qβ, and bacteriophage Φ6. Inactivation of alkaline phosphatase enzyme proteins on these materials was confirmed. Antiviral activity against bacteriophage Φ6 of LMO was improved by substituting Ce. Hydrophobicity and UV shielding performance were also confirmed for this material.
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Affiliation(s)
- Takumi Matsumoto
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8550, Japan
| | - Kayano Sunada
- Antibacterial and Antiviral Research Group, Kanagawa Institute of Industrial Science and Technology, LiSE4c-1, 3-25-13 Tonomachi, Kawasaki-ku, Kawasaki, Kanagawa 210-0821, Japan
| | - Takeshi Nagai
- Antibacterial and Antiviral Research Group, Kanagawa Institute of Industrial Science and Technology, LiSE4c-1, 3-25-13 Tonomachi, Kawasaki-ku, Kawasaki, Kanagawa 210-0821, Japan
| | - Toshihiro Isobe
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8550, Japan.
| | - Sachiko Matsushita
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8550, Japan
| | - Hitoshi Ishiguro
- Antibacterial and Antiviral Research Group, Kanagawa Institute of Industrial Science and Technology, LiSE4c-1, 3-25-13 Tonomachi, Kawasaki-ku, Kawasaki, Kanagawa 210-0821, Japan
| | - Akira Nakajima
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8550, Japan.
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Rotavirus Calcium Dysregulation Manifests as Dynamic Calcium Signaling in the Cytoplasm and Endoplasmic Reticulum. Sci Rep 2019; 9:10822. [PMID: 31346185 PMCID: PMC6658527 DOI: 10.1038/s41598-019-46856-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/04/2019] [Indexed: 02/08/2023] Open
Abstract
Like many viruses, rotavirus (RV) dysregulates calcium homeostasis by elevating cytosolic calcium ([Ca2+]cyt) and decreasing endoplasmic reticulum (ER) stores. While an overall, monophasic increase in [Ca2+]cyt during RV infection has been shown, the nature of the RV-induced aberrant calcium signals and how they manifest over time at the single-cell level have not been characterized. Thus, we generated cell lines and human intestinal enteroids (HIEs) stably expressing cytosolic and/or ER-targeted genetically-encoded calcium indicators to characterize calcium signaling throughout RV infection by time-lapse imaging. We found that RV induces highly dynamic [Ca2+]cyt signaling that manifest as hundreds of discrete [Ca2+]cyt spikes, which increase during peak infection. Knockdown of nonstructural protein 4 (NSP4) attenuates the [Ca2+]cyt spikes, consistent with its role in dysregulating calcium homeostasis. RV-induced [Ca2+]cyt spikes were primarily from ER calcium release and were attenuated by inhibiting the store-operated calcium entry (SOCE) channel Orai1. RV-infected HIEs also exhibited prominent [Ca2+]cyt spikes that were attenuated by inhibiting SOCE, underlining the relevance of these [Ca2+]cyt spikes to gastrointestinal physiology and role of SOCE in RV pathophysiology. Thus, our discovery that RV increases [Ca2+]cyt by dynamic calcium signaling, establishes a new, paradigm-shifting understanding of the spatial and temporal complexity of virus-induced calcium signaling.
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Abstract
BACKGROUND Persistent diarrhoea (PD), defined as diarrhoeal symptoms for longer than 2 weeks, still forms a substantial disease burden in children under 5 years of age. This article provides an overview of the current knowledge of PD and discusses novel concepts. METHODS A literature search on PD was performed which focused on evidence on epidemiology, pathophysiology and management of the disease. RESULTS The prevalence of PD has potentially decreased over the last decades. Debate remains around the role of specific bacterial, viral and parasitic infections with PD. PD is associated with malnutrition and a compromised immune system, including that caused by HIV infection. Management includes fluid resuscitation and improving nutritional status. There is a lack of evidence on the use of antibiotic therapy for PD. There is increasing interest in nutrient-based interventions, including pre- and/or probiotics that can modify the microbiome and thereby potentially prevent or improve the outcome of PD in children. CONCLUSION As PD remains a significant health burden, multicentre clinical trials are needed to inform future treatment guidelines. ABBREVIATIONS PD, persistent diarrhoea; EED, environmental enteric dysfunction; IBD, inflammatory bowel disease; WHO, World Health Organization.
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Affiliation(s)
- Robert H J Bandsma
- a Division of Gastroenterology, Hepatology and Nutrition , Hospital for Sick Children , Toronto , Canada.,b Translational Medicine Program, Hospital for Sick Children , Toronto , Canada.,c Centre for Global Child Health, Hospital for Sick Children , Toronto , Canada.,d Department of Nutrition Sciences , University of Toronto , Toronto , Canada
| | - Kamran Sadiq
- e Department of Paediatrics and Child Health , Aga Khan University , Karachi , Pakistan
| | - Zulfiqar A Bhutta
- c Centre for Global Child Health, Hospital for Sick Children , Toronto , Canada.,d Department of Nutrition Sciences , University of Toronto , Toronto , Canada.,e Department of Paediatrics and Child Health , Aga Khan University , Karachi , Pakistan
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Bentes GA, Guimarães JR, Volotão EDM, Fialho AM, Hooper C, Ganime AC, Gardinali NR, Lanzarini NM, da Silva ADS, Pitcovski J, Leite JP, Pinto MA. Cynomolgus Monkeys ( Macaca fascicularis) as an Experimental Infection Model for Human Group A Rotavirus. Viruses 2018; 10:v10070355. [PMID: 29973483 PMCID: PMC6071073 DOI: 10.3390/v10070355] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/23/2018] [Accepted: 04/27/2018] [Indexed: 12/25/2022] Open
Abstract
Group A rotaviruses (RVA) are one of the most common causes of severe acute gastroenteritis in infants worldwide. Rotaviruses spread from person to person, mainly by faecal–oral transmission. Almost all unvaccinated children may become infected with RVA in the first two years of life. The establishment of an experimental monkey model with RVA is important to evaluate new therapeutic approaches. In this study, we demonstrated viral shedding and viraemia in juvenile–adult Macaca fascicularis orally inoculated with Wa RVA prototype. Nine monkeys were inoculated orally: seven animals with human RVA and two control animals with saline solution. During the study, the monkeys were clinically monitored, and faeces and blood samples were tested for RVA infection. In general, the inoculated animals developed an oligosymptomatic infection pattern. The main clinical symptoms observed were diarrhoea in two monkeys for three days, associated with a reduction in plasmatic potassium content. Viral RNA was detected in seven faecal and five sera samples from inoculated animals, suggesting virus replication. Cynomolgus monkeys are susceptible hosts for human Wa RVA infection. When inoculated orally, they presented self-limited diarrhoea associated with presence of RVA infectious particles in faeces. Thus, cynomolgus monkeys may be useful as animal models to evaluate the efficacy of new antiviral approaches.
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Affiliation(s)
- Gentil Arthur Bentes
- Laboratório de Desenvolvimento Tecnológico em Virologia, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Juliana Rodrigues Guimarães
- Laboratório de Desenvolvimento Tecnológico em Virologia, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Eduardo de Mello Volotão
- Laboratório de Virologia Comparada e Ambiental, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Alexandre Madi Fialho
- Laboratório de Virologia Comparada e Ambiental, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Cleber Hooper
- Serviço de Controle da Qualidade Animal, Instituto de Ciência e Tecnologia em Biomodelos, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Ana Carolina Ganime
- Laboratório de Virologia Comparada e Ambiental, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Noemi Rovaris Gardinali
- Laboratório de Desenvolvimento Tecnológico em Virologia, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Natália Maria Lanzarini
- Laboratório de Desenvolvimento Tecnológico em Virologia, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Alexandre Dos Santos da Silva
- Laboratório de Desenvolvimento Tecnológico em Virologia, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Jacob Pitcovski
- Virology and Vaccine Development Laboratory, MIGAL Technology Center, Kiryat Shmona 11016, Israel.
| | - José Paulo Leite
- Laboratório de Virologia Comparada e Ambiental, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
| | - Marcelo Alves Pinto
- Laboratório de Desenvolvimento Tecnológico em Virologia, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro/RJ 21.040-360, Brazil.
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Sánchez G, Estrada O, Acha G, Cardozo A, Peña F, Ruiz MC, Michelangeli F, Alvarado-Castillo C. The norpurpureine alkaloid from Annona purpurea inhibits human platelet activation in vitro. Cell Mol Biol Lett 2018; 23:15. [PMID: 29713353 PMCID: PMC5905151 DOI: 10.1186/s11658-018-0082-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 04/09/2018] [Indexed: 01/01/2023] Open
Abstract
Background The leaves of Annona purpurea have yielded several alkaloids with anti-aggregation activities against rabbit platelets. This is promising in the search for agents that might act against platelets and reduce the incidence of cardiovascular diseases. Since significant differences in platelet function have been reported between human and animal platelets, a study focusing on the effect of A. purpurea extracts against human platelet activation is necessary. Methods The compounds in an A. purpurea ethanolic extract underwent bio-guided fractionation and were used for in vitro human platelet aggregation assays to isolate the compounds with anti-platelet activity. The bioactive compounds were identified by spectroscopic analysis. Additional platelet studies were performed to characterize their action as inhibitors of human platelet activation. Results The benzylisoquinoline alkaloid norpurpureine was identified as the major anti-platelet compound. The IC50 for norpurpureine was 80 μM against platelets when stimulated with adenosine 5′-diphosphate (ADP), collagen and thrombin. It was pharmacologically effective from 20 to 220 μM. Norpurpureine (220 μM) exhibited its in vitro effectiveness in samples from 30 healthy human donors who did not take any drugs during the 2 weeks prior to the collection. Norpurpureine also gradually inhibited granule secretion and adhesion of activated platelets to immobilized fibrinogen. At the intra-platelet level, norpurpureine prevented agonist-stimulated calcium mobilization and cAMP reduction. Structure–activity relationship analysis indicates that the lack of a methyl group at the nitrogen seems to be key in the ability of the compound to interact with its molecular target. Conclusion Norpurpureine displays a promising in vitro pharmacological profile as an inhibitor of human platelet activation. Its molecular target could be a common effector between Ca2+ and cAMP signaling, such as the PLC-PKC-Ca2+ pathway and PDEs. This needs further evaluation at the protein isoform level. Electronic supplementary material The online version of this article (10.1186/s11658-018-0082-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gabriela Sánchez
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Omar Estrada
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Giovana Acha
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Alfonso Cardozo
- 2Laboratorio de Botánica Sistemática, Facultad de Agronomía, Universidad Central de Venezuela (UCV), Maracay, Bolivarian Republic of Venezuela
| | - Franshelle Peña
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Marie Christine Ruiz
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Fabián Michelangeli
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Claudia Alvarado-Castillo
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela.,3Laboratorio de Hemostasia y Genética Vascular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Apartado 20632, K11 de la Carretera Panamericana, Caracas, 1020-A Bolivarian Republic of Venezuela
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13
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Abstract
Eukaryotic cells have evolved a myriad of ion channels, transporters, and pumps to maintain and regulate transmembrane ion gradients. As intracellular parasites, viruses also have evolved ion channel proteins, called viroporins, which disrupt normal ionic homeostasis to promote viral replication and pathogenesis. The first viral ion channel (influenza M2 protein) was confirmed only 23 years ago, and since then studies on M2 and many other viroporins have shown they serve critical functions in virus entry, replication, morphogenesis, and immune evasion. As new candidate viroporins and viroporin-mediated functions are being discovered, we review the experimental criteria for viroporin identification and characterization to facilitate consistency within this field of research. Then we review recent studies on how the few Ca(2+)-conducting viroporins exploit host signaling pathways, including store-operated Ca(2+) entry, autophagy, and inflammasome activation. These viroporin-induced aberrant Ca(2+) signals cause pathophysiological changes resulting in diarrhea, vomiting, and proinflammatory diseases, making both the viroporin and host Ca(2+) signaling pathways potential therapeutic targets for antiviral drugs.
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Affiliation(s)
- Joseph M Hyser
- Alkek Center for Metagenomic and Microbiome Research.,Department of Molecular Virology and Microbiology, and
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, and.,Department of Medicine, Baylor College of Medicine, Houston, Texas 77030-3411;
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14
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Lobeck I, Donnelly B, Dupree P, Mahe MM, McNeal M, Mohanty SK, Tiao G. Rhesus rotavirus VP6 regulates ERK-dependent calcium influx in cholangiocytes. Virology 2016; 499:185-195. [PMID: 27668997 DOI: 10.1016/j.virol.2016.09.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/12/2016] [Accepted: 09/14/2016] [Indexed: 12/24/2022]
Abstract
The Rhesus rotavirus (RRV) induced murine model of biliary atresia (BA) is a useful tool in studying the pathogenesis of this neonatal biliary obstructive disease. In this model, the mitogen associated protein kinase pathway is involved in RRV infection of biliary epithelial cells (cholangiocytes). We hypothesized that extracellular signal-related kinase (ERK) phosphorylation is integral to calcium influx, allowing for viral replication within the cholangiocyte. Utilizing ERK and calcium inhibitors in immortalized cholangiocytes and BALB/c pups, we determined that ERK inhibition resulted in reduced viral yield and subsequent decreased symptomatology in mice. In vitro, the RRV VP6 protein induced ERK phosphorylation, leading to cellular calcium influx. Pre-treatment with an ERK inhibitor or Verapamil resulted in lower viral yields. We conclude that the pathogenesis of RRV-induced murine BA is dependent on the VP6 protein causing ERK phosphorylation and triggering calcium influx allowing replication in cholangiocytes.
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Affiliation(s)
- Inna Lobeck
- Department of Pediatric and Thoracic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Bryan Donnelly
- Department of Pediatric and Thoracic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Phylicia Dupree
- Department of Pediatric and Thoracic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Maxime M Mahe
- Department of Pediatric and Thoracic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Monica McNeal
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Sujit K Mohanty
- Department of Pediatric and Thoracic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Greg Tiao
- Department of Pediatric and Thoracic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
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15
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Perry JL, Ramachandran NK, Utama B, Hyser JM. Use of genetically-encoded calcium indicators for live cell calcium imaging and localization in virus-infected cells. Methods 2015; 90:28-38. [PMID: 26344758 PMCID: PMC4655165 DOI: 10.1016/j.ymeth.2015.09.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 01/09/2023] Open
Abstract
Calcium signaling is a ubiquitous and versatile process involved in nearly every cellular process, and exploitation of host calcium signals is a common strategy used by viruses to facilitate replication and cause disease. Small molecule fluorescent calcium dyes have been used by many to examine changes in host cell calcium signaling and calcium channel activation during virus infections, but disadvantages of these dyes, including poor loading and poor long-term retention, complicate analysis of calcium imaging in virus-infected cells due to changes in cell physiology and membrane integrity. The recent expansion of genetically-encoded calcium indicators (GECIs), including blue and red-shifted color variants and variants with calcium affinities appropriate for calcium storage organelles like the endoplasmic reticulum (ER), make the use of GECIs an attractive alternative for calcium imaging in the context of virus infections. Here we describe the development and testing of cell lines stably expressing both green cytoplasmic (GCaMP5G and GCaMP6s) and red ER-targeted (RCEPIAer) GECIs. Using three viruses (rotavirus, poliovirus and respiratory syncytial virus) previously shown to disrupt host calcium homeostasis, we show the GECI cell lines can be used to detect simultaneous cytoplasmic and ER calcium signals. Further, we demonstrate the GECI expression has sufficient stability to enable long-term confocal imaging of both cytoplasmic and ER calcium during the course of virus infections.
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Affiliation(s)
- Jacob L Perry
- Department of Molecular Virology and Microbiology and Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, Houston, TX 77030, United States
| | - Nina K Ramachandran
- Department of Molecular Virology and Microbiology and Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, Houston, TX 77030, United States
| | - Budi Utama
- Shared Equipment Authority, Rice University, Houston, TX 77030, United States
| | - Joseph M Hyser
- Department of Molecular Virology and Microbiology and Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, Houston, TX 77030, United States.
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16
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Activation of the endoplasmic reticulum calcium sensor STIM1 and store-operated calcium entry by rotavirus requires NSP4 viroporin activity. J Virol 2013; 87:13579-88. [PMID: 24109210 DOI: 10.1128/jvi.02629-13] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Rotavirus nonstructural protein 4 (NSP4) induces dramatic changes in cellular calcium homeostasis. These include increased endoplasmic reticulum (ER) permeability, resulting in decreased ER calcium stores and activation of plasma membrane (PM) calcium influx channels, ultimately causing a 2- to 4-fold elevation in cytoplasmic calcium. Elevated cytoplasmic calcium is absolutely required for virus replication, but the underlying mechanisms responsible for calcium influx remain poorly understood. NSP4 is an ER-localized viroporin, whose activity depletes ER calcium, which ultimately leads to calcium influx. We hypothesized that NSP4-mediated depletion of ER calcium activates store-operated calcium entry (SOCE) through activation of the ER calcium sensor stromal interaction molecule 1 (STIM1). We established and used a stable yellow fluorescent protein-expressing STIM1 cell line (YFP-STIM1) as a biosensor to assess STIM1 activation (puncta formation) by rotavirus infection and NSP4 expression. We found that STIM1 is constitutively active in rotavirus-infected cells and that STIM1 puncta colocalize with the PM-localized Orai1 SOCE calcium channel. Expression of wild-type NSP4 activated STIM1, resulting in PM calcium influx, but an NSP4 viroporin mutant failed to induce STIM1 activation and did not activate the PM calcium entry pathway. Finally, knockdown of STIM1 significantly reduced rotavirus yield, indicating STIM1 plays a critical role in virus replication. These data demonstrate that while rotavirus may ultimately activate multiple calcium channels in the PM, calcium influx is predicated on NSP4 viroporin-mediated activation of STIM1 in the ER. This is the first report of viroporin-mediated activation of SOCE, reinforcing NSP4 as a robust model to understand dysregulation of calcium homeostasis during virus infections.
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17
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Dissecting the Ca²⁺ entry pathways induced by rotavirus infection and NSP4-EGFP expression in Cos-7 cells. Virus Res 2012; 167:285-96. [PMID: 22634036 DOI: 10.1016/j.virusres.2012.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/13/2012] [Accepted: 05/16/2012] [Indexed: 01/09/2023]
Abstract
Rotavirus infection modifies Ca(2+) homeostasis provoking an increase in Ca(2+) permeation, cytoplasmic Ca(2+) concentration ([Ca(2+)](cyto)), total Ca(2+) pools and, a decrease of Ca(2+) response to agonists. These effects are mediated by NSP4. The mechanism by which NSP4 deranges Ca(2+) homeostasis is not yet known. It has been proposed that the increase in [Ca(2+)](cyto) is the result of Ca(2+) release from intracellular stores, thereby activating store-operated Ca(2+) entry (SOCE). We studied the mechanisms involved in the changes of Ca(2+) permeability of the plasma membrane elicited by rotavirus infection and NSP4 expression in Cos-7 cells loaded with fura-2 or fluo-4, using inhibitors and activators of different pathways. Total depletion of ER Ca(2+) stores induced by thapsigargin or ATP was not able to elicit Ca(2+) entry in mock-infected cells to the level attained with infection or NSP4-EGFP expression. The pathway induced by NSP4-EGFP expression or infection shows properties shared by SOCE: it can be inactivated by high [Ca(2+)](cyto), is permeable to Mn(2+) and inhibited by La(3+) and the SOC inhibitor 2-aminoethoxydiphenyl borate (2-APB). Contribution of the agonist-operated channels (AOCs) to Ca(2+) entry is small and not modified by infection. The plasma membrane permeability to Ca(2+) in rotavirus infected or NSP4-EGFP expressing cells is also blocked by KB-R7943, an inhibitor of the plasma membrane Na(+)/Ca(2+) exchanger (NCX), operating in its reverse mode. In conclusion, the expression of NSP4 in infected Cos-7 cells appears to activate the NCX in reverse mode and the SOCE pathway to induce increased Ca(2+) entry.
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18
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Halasz P, Holloway G, Coulson BS. Death mechanisms in epithelial cells following rotavirus infection, exposure to inactivated rotavirus or genome transfection. J Gen Virol 2010; 91:2007-2018. [PMID: 20392902 DOI: 10.1099/vir.0.018275-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Intestinal epithelial cell death following rotavirus infection is associated with villus atrophy and gastroenteritis. Roles for both apoptosis and necrosis in cytocidal activity within rotavirus-infected epithelial cells have been proposed. Additionally, inactivated rotavirus has been reported to induce diarrhoea in infant mice. We further examined the death mechanisms induced in epithelial cell lines following rotavirus infection or inactivated rotavirus exposure. Monolayer integrity changes in MA104, HT-29 and partially differentiated Caco-2 cells following inactivated rotavirus exposure or RRV or CRW-8 rotavirus infection paralleled cell metabolic activity and viability reductions. MA104 cell exposure to rotavirus dsRNA also altered monolayer integrity. Inactivated rotaviruses induced delayed cell function losses that were unrelated to apoptosis. Phosphatidylserine externalization, indicating early apoptosis, occurred in MA104 and HT-29 but not in partially differentiated Caco-2 cells by 11 h after infection. Rotavirus activation of phosphatidylinositol 3-kinase partially protected MA104 and HT-29 cells from early apoptosis. In contrast, activation of the stress-activated protein kinase JNK by rotavirus did not influence apoptosis induction in these cells. RRV infection produced DNA fragmentation, indicating late-stage apoptosis, in fully differentiated Caco-2 cells only. These studies show that the apoptosis initiation and cell death mechanism induced by rotavirus infection depend on cell type and degree of differentiation. Early stage apoptosis resulting from rotavirus infection is probably counter-balanced by virus-induced phosphatidylinositol 3-kinase activation. The ability of inactivated rotaviruses and rotavirus dsRNA to perturb monolayer integrity supports a potential role for these rotavirus components in disease pathogenesis.
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Affiliation(s)
- Peter Halasz
- Department of Microbiology and Immunology, The University of Melbourne, VIC 3010, Australia
| | - Gavan Holloway
- Department of Microbiology and Immunology, The University of Melbourne, VIC 3010, Australia
| | - Barbara S Coulson
- Department of Microbiology and Immunology, The University of Melbourne, VIC 3010, Australia
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19
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Bahat A, Eisenbach M. Human Sperm Thermotaxis Is Mediated by Phospholipase C and Inositol Trisphosphate Receptor Ca2+ Channel1. Biol Reprod 2010; 82:606-16. [DOI: 10.1095/biolreprod.109.080127] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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20
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Zhou Y, Frey TK, Yang JJ. Viral calciomics: interplays between Ca2+ and virus. Cell Calcium 2009; 46:1-17. [PMID: 19535138 PMCID: PMC3449087 DOI: 10.1016/j.ceca.2009.05.005] [Citation(s) in RCA: 217] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Revised: 05/15/2009] [Accepted: 05/18/2009] [Indexed: 12/23/2022]
Abstract
Ca2+ is one of the most universal and versatile signaling molecules and is involved in almost every aspect of cellular processes. Viruses are adept at utilizing the universal Ca2+ signal to create a tailored cellular environment that meets their own demands. This review summarizes most of the known mechanisms by which viruses perturb Ca2+ homeostasis and utilize Ca2+ and cellular Ca2+-binding proteins to their benefit in their replication cycles. Ca2+ plays important roles in virion structure formation, virus entry, viral gene expression, posttranslational processing of viral proteins and virion maturation and release. As part of the review, we introduce an algorithm to identify linear “EF-hand” Ca2+-binding motifs which resulted in the prediction of a total of 93 previously unrecognized Ca2+-binding motifs in virus proteins. Many of these proteins are nonstructural proteins, a class of proteins among which Ca2+ interactions had not been formerly appreciated. The presence of linear Ca2+-binding motifs in viral proteins enlarges the spectrum of Ca2+–virus interplay and expands the total scenario of viral calciomics.
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Affiliation(s)
- Yubin Zhou
- Department of Chemistry, Georgia State University, 50 Decatur St., Atlanta, GA 30303 USA
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21
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Díaz Y, Chemello ME, Peña F, Aristimuño OC, Zambrano JL, Rojas H, Bartoli F, Salazar L, Chwetzoff S, Sapin C, Trugnan G, Michelangeli F, Ruiz MC. Expression of nonstructural rotavirus protein NSP4 mimics Ca2+ homeostasis changes induced by rotavirus infection in cultured cells. J Virol 2008; 82:11331-43. [PMID: 18787006 PMCID: PMC2573286 DOI: 10.1128/jvi.00577-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Accepted: 07/28/2008] [Indexed: 12/22/2022] Open
Abstract
Rotavirus infection modifies Ca(2+) homeostasis, provoking an increase in Ca(2+) permeation, the cytoplasmic Ca(2+) concentration ([Ca(2+)](cyto)), and total Ca(2+) pools and a decrease in Ca(2+) response to agonists. A glycosylated viral protein(s), NSP4 and/or VP7, may be responsible for these effects. HT29 or Cos-7 cells were infected by the SA11 clone 28 strain, in which VP7 is not glycosylated, or transiently transfected with plasmids coding for NSP4-enhanced green fluorescent protein (EGFP) or NSP4. The permeability of the plasma membrane to Ca(2+) and the amount of Ca(2+) sequestered in the endoplasmic reticulum released by carbachol or ATP were measured in fura-2-loaded cells at the single-cell level under a fluorescence microscope or in cell suspensions in a fluorimeter. Total cell Ca(2+) pools were evaluated as (45)Ca(2+) uptake. Infection with SA11 clone 28 induced an increase in Ca(2+) permeability and (45)Ca(2+) uptake similar to that found with the normally glycosylated SA11 strain. These effects were inhibited by tunicamycin, indicating that inhibition of glycosylation of a viral protein other than VP7 affects the changes of Ca(2+) homeostasis induced by infection. Expression of NSP4-EGFP or NSP4 in transfected cells induced the same changes observed with rotavirus infection, whereas the expression of EGFP or EGFP-VP4 showed the behavior of uninfected and untransfected cells. Increased (45)Ca(2+) uptake was also observed in cells expressing NSP4-EGFP or NSP4, as evidenced in rotavirus infection. These results indicate that glycosylated NSP4 is primarily responsible for altering the Ca(2+) homeostasis of infected cells through an initial increase of cell membrane permeability to Ca(2+).
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Affiliation(s)
- Yuleima Díaz
- Laboratorio de Fisiología Gastrointestinal, IVIC, Caracas 1020A, Venezuela
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22
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Silencing of rotavirus NSP4 or VP7 expression reduces alterations in Ca2+ homeostasis induced by infection of cultured cells. J Virol 2008; 82:5815-24. [PMID: 18400845 DOI: 10.1128/jvi.02719-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Rotavirus infection of cells in culture induces major changes in Ca(2+) homeostasis. These changes include increases in plasma membrane Ca(2+) permeability, cytosolic Ca(2+) concentration, and total cell Ca(2+) content and a reduction in the amount of Ca(2+) released from intracellular pools sensitive to agonists. Various lines of evidence suggest that the nonstructural glycoprotein NSP4 and possibly the major outer capsid glycoprotein VP7 are responsible for these effects. In order to evaluate the functional roles of NSP4 and other rotavirus proteins in the changes in Ca(2+) homeostasis observed in infected cells, the expressions of NSP4, VP7, and VP4 were silenced using the short interfering RNA (siRNA) technique. The transfection of specific siRNAs resulted in a strong and specific reduction of the expression of NSP4, VP7, and VP4 and decreased the yield of new viral progeny by more than 90%. Using fura-2 loaded cells, we observed that knocking down the expression of NSP4 totally prevented the increase in Ca(2+) permeability of the plasma membrane and cytosolic Ca(2+) concentration measured in infected cells. A reduction in the levels of VP7 expression partially reduced the effect of infection on plasma membrane Ca(2+) permeability and Ca(2+) pools released by agonist (ATP). In addition, the increase of total Ca(2+) content (as measured by (45)Ca(2+) uptake) observed in infected cells was reduced to the levels in mock-infected cells when NSP4 and VP7 were silenced. Finally, when the expression of VP4 was silenced, none of the disturbances of Ca(2+) homeostasis caused by rotaviruses in infected cells were affected. These data altogether indicate that NSP4 is the main protein responsible for the changes in Ca(2+) homeostasis observed in rotavirus-infected cultured cells. Nevertheless, VP7 may contribute to these effects.
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Molecular epidemiology of rotavirus diarrhea among children in Saudi Arabia: first detection of G9 and G12 strains. J Clin Microbiol 2008; 46:1185-91. [PMID: 18234870 DOI: 10.1128/jcm.02244-07] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In anticipation of rotavirus vaccine introduction in Saudi Arabia, this study was undertaken to determine the distribution of the G and P genotypes of rotaviruses in order to examine whether there was any emerging serotype or unusual strain circulating in children in Saudi Arabia. Of 984 stool specimens collected between 17 April 2004 and 16 April 2005, rotavirus was detected by an enzyme-linked immunosorbent assay in 187 (19%) diarrheal children less than 5 years of age. Of these, 160 (86%) were classified into G and P genotypes as follows: G1P[8] (44%), G2P[4] (20%), G9P[8] (11%), G12P[8] (4%), and G3P[8] (4%). RNA polyacrylamide gel electrophoresis identified 94 (50%) specimens as long RNA patterns, 30 (16%) specimens as short RNA patterns, and 1 mixed infection. Only a single long RNA electropherotype was identified for seven specimens containing G12P[8] rotavirus. RNA-RNA hybridization demonstrated that the G12P[8] strains were similar in their genomic constellation to locally cocirculating strains and to a Nepalese G12P[8] strain. The Saudi Arabian G12 VP7 gene had a 99% nucleotide sequence identity with Nepalese and Indian G12 VP7 genes and belonged to the third lineage. This study is the first to describe the distribution of rotavirus G and P types and also the first to identify G9P[8] and G12P[8] strains in the country.
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Antoine AF, Montpellier C, Cailliau K, Browaeys-Poly E, Vilain JP, Dubuisson J. The Alphavirus 6K Protein Activates Endogenous Ionic Conductances when Expressed in Xenopus Oocytes. J Membr Biol 2007; 215:37-48. [PMID: 17483865 DOI: 10.1007/s00232-007-9003-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Accepted: 01/08/2007] [Indexed: 02/03/2023]
Abstract
The Alphavirus Sindbis 6K protein is involved in several functions. It contributes to the processing and membrane insertion of E1 and PE2 viral envelope glycoproteins and to virus budding. It also permeabilizes Escherichia coli and mammalian cells. These viroporin-like properties have been proposed to help virus budding by modifying membrane permeabilities. We expressed Sindbis virus 6K cRNA in Xenopus oocytes to further characterize the effect of 6K on membrane conductances and permeabilization. Although no intrinsic channel properties were seen, cell shrinkage was observed within 24 h. Voltage-clamp experiments showed that 6K upregulated endogenous currents: a hyperpolarization-activated inward current (I (in)) and a calcium-dependent chloride current (I (Cl)). 6K was located at both the plasma and the endoplasmic reticulum membranes. The plasma membrane current upregulation likely results from disruption of the calcium homeostasis of the cell at the endoplasmic reticulum level. Indeed, 6K cRNA expression induced reticular calcium store depletion and capacitative calcium entry activation. By experimental modifications of the incubation medium, we showed that downstream of these events cell shrinkage resulted from a 6K -induced KCl efflux (I (Cl) upregulation leads to chloride efflux, which itself electrically drives potassium efflux), which was responsible for an osmotic water efflux. Our data confirm that 6K specifically triggers a sequential cascade of events that leads to cytoplasmic calcium elevation and cell permeabilization, which likely play a role in the Sindbis virus life cycle.
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Affiliation(s)
- Anne-Frédérique Antoine
- Equipe d'Accueil 4020, Institut Fédératif de la Recherche 147, Université de Lille, 59655 Villeneuve d'Ascq Cedex, France.
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25
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Chami M, Oulès B, Paterlini-Bréchot P. Cytobiological consequences of calcium-signaling alterations induced by human viral proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1344-62. [PMID: 17059849 DOI: 10.1016/j.bbamcr.2006.09.025] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 09/13/2006] [Accepted: 09/15/2006] [Indexed: 01/25/2023]
Abstract
Since calcium-signaling regulates specific and fundamental cellular processes, it represents the ideal target of viral proteins, in order for the virus to control cellular functions and favour its persistence, multiplication and spread. A detailed analysis of reports focused on the impact of viral proteins on calcium-signaling has shown that virus-related elevations of cytosolic calcium levels allow increased viral protein expression (HIV-1, HSV-1/2), viral replication (HBx, enterovirus 2B, HTLV-1 p12(I), HHV-8, EBV), viral maturation (rotavirus), viral release (enterovirus 2B) and cell immortalization (EBV). Interestingly, virus-induced decreased cytosolic calcium levels have been found to be associated with inhibition of immune cells functions (HIV-1 Tat, HHV-8 K15, EBV LMP2A). Finally, several viral proteins are able to modulate intracellular calcium-signaling to control cell viability (HIV-1 Tat, HTLV-1 p13(II), HCV core, HBx, enterovirus 2B, HHV-8 K7). These data point out calcium-signaling as a key cellular target for viral infection and should stimulate further studies exploring new calcium-related therapeutic strategies.
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26
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Ruiz MC, Díaz Y, Peña F, Aristimuño OC, Chemello ME, Michelangeli F. Ca2+ permeability of the plasma membrane induced by rotavirus infection in cultured cells is inhibited by tunicamycin and brefeldin A. Virology 2005; 333:54-65. [PMID: 15708592 DOI: 10.1016/j.virol.2004.12.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Revised: 11/18/2004] [Accepted: 12/05/2004] [Indexed: 11/17/2022]
Abstract
Rotavirus infection of cultured cells induces a progressive increase in plasma membrane permeability to Ca2+. The viral product responsible for this effect is not known. We have used tunicamycin and brefeldin A to prevent glycosylation and membrane traffic and study the involvement of viral glycoproteins, NSP4 and/or VP7, in rotavirus-infected HT29 and MA104 cells. In infected cells, we observed an increase of plasma membrane Ca2+ permeability and a progressive depletion of agonist-releasable ER pools measured with fura 2 and an enhancement of total Ca2+ content measured as 45Ca2+ uptake. Tunicamycin inhibited the increase in membrane Ca2+ permeability, induced a depletion of agonist-releasable and 45Ca2+-sequestered pools. Brefeldin A inhibited the increase of Ca2+ permeability and the increase in 45Ca2+ uptake induced by infection. We propose that the glycosylated viral product NSP4 (and/or VP7) travels to the plasma membrane to form a Ca2+ channel and hence elevate Ca2+ permeability.
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Affiliation(s)
- Marie Christine Ruiz
- Laboratorio de Fisiología Gastrointestinal, Instituto Venezolano de Investigaciones Científicas, Caracas 1020A, Venezuela.
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27
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López T, Camacho M, Zayas M, Nájera R, Sánchez R, Arias CF, López S. Silencing the morphogenesis of rotavirus. J Virol 2005; 79:184-92. [PMID: 15596814 PMCID: PMC538724 DOI: 10.1128/jvi.79.1.184-192.2005] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The morphogenesis of rotaviruses follows a unique pathway in which immature double-layered particles (DLPs) assembled in the cytoplasm bud across the membrane of the endoplasmic reticulum (ER), acquiring during this process a transient lipid membrane which is modified with the ER resident viral glycoproteins NSP4 and VP7; these enveloped particles also contain VP4. As the particles move towards the interior of the ER cisternae, the transient lipid membrane and the nonstructural protein NSP4 are lost, while the virus surface proteins VP4 and VP7 rearrange to form the outermost virus protein layer, yielding mature infectious triple-layered particles (TLPs). In this work, we have characterized the role of NSP4 and VP7 in rotavirus morphogenesis by silencing the expression of both glycoproteins through RNA interference. Silencing the expression of either NSP4 or VP7 reduced the yield of viral progeny by 75 to 80%, although the underlying mechanism of this reduction was different in each case. Blocking the synthesis of NSP4 affected the intracellular accumulation and the cellular distribution of several viral proteins, and little or no virus particles (neither DLPs nor TLPs) were assembled. VP7 silencing, in contrast, did not affect the expression or distribution of other viral proteins, but in its absence, enveloped particles accumulated within the lumen of the ER, and no mature infectious virus was produced. Altogether, these results indicate that during a viral infection, NSP4 serves as a receptor for DLPs on the ER membrane and drives the budding of these particles into the ER lumen, while VP7 is required for removing the lipid envelope during the final step of virus morphogenesis.
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Affiliation(s)
- Tomas López
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
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28
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Golantsova NE, Gorbunova EE, Mackow ER. Discrete domains within the rotavirus VP5* direct peripheral membrane association and membrane permeability. J Virol 2004; 78:2037-44. [PMID: 14747568 PMCID: PMC369428 DOI: 10.1128/jvi.78.4.2037-2044.2004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cleavage of the rotavirus spike protein, VP4, is required for rotavirus-induced membrane permeability and viral entry into cells. The VP5* cleavage product selectively permeabilizes membranes and liposomes and contains an internal hydrophobic domain that is required for membrane permeability. Here we investigate VP5* domains (residues 248 to 474) that direct membrane binding. We determined that expressed VP5 fragments containing residues 248 to 474 or 265 to 474, including the internal hydrophobic domain, bind to cellular membranes but are not present in Triton X-100-resistant membrane rafts. Expressed VP5 partitions into aqueous but not detergent phases of Triton X-114, suggesting that VP5 is not integrally inserted into membranes. Since high-salt or alkaline conditions eluted VP5 from membranes, our findings demonstrate that VP5 is peripherally associated with membranes. Interestingly, mutagenesis of residue 394 (W-->R) within the VP5 hydrophobic domain, which abolishes VP5-directed permeability, had no effect on VP5's peripheral membrane association. In contrast, deletion of N-terminal VP5 residues (residues 265 to 279) abolished VP5 binding to membranes. Alanine mutagenesis of two positively charged residues within this domain (residues 274R and 276K) dramatically reduced (>95%) binding of VP5 to membranes and suggested their potential interaction with polar head groups of the lipid bilayer. Mutations in either the VP5 hydrophobic or basic domain blocked VP5-directed permeability of cells. These findings indicate that there are at least two discrete domains within VP5* required for pore formation: an N-terminal basic domain that permits VP5* to peripherally associate with membranes and an internal hydrophobic domain that is essential for altering membrane permeability. These results provide a fundamental understanding of interactions between VP5* and the membrane, which are required for rotavirus entry.
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Affiliation(s)
- Nina E Golantsova
- Department of Medicine, Stony Brook University, Stony Brook, New York 11794, USA
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Larsen P, Schleihauf E, Yu H, Prior T, Rangachari PK. Calcium-stimulated short-circuit currents in the canine proximal colonic epithelium: effects of DK-PGD2, a metabolite of prostaglandin D2. Can J Physiol Pharmacol 2002; 80:1085-94. [PMID: 12489928 DOI: 10.1139/y02-139] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prostaglandin D2 (PGD2) has marked inhibitory effects on the canine proximal colonic epithelium set up in Ussing chambers. These effects involved a receptor that is pharmacologically distinct from the classical DP, presumably the recently identified CRTH2/DP2 variety. The mechanism underlying these effects was studied using 13,14-dihydro-15-keto-PGD2 (DK-PGD2), a stable metabolite of the parent prostanoid. The metabolite quickly reversed short circuit currents (I(sc)) stimulated by diverse agonists. Greater inhibitory effects were seen with stimulants such as carbachol and cyclopiazonic acid (CPA) rather than with forskolin or protein kinase A activators. Since the same stimulants were differentially affected by removal and replacement of serosal Ca2+, we tested the possibility that the prostanoid inhibited basolateral Ca2+ entry. In the absence of serosal Ca2+, tissues primed with CPA demonstrated concentration-dependent increases in I(sc), to cumulative additions of Ca2+ or Sr2+, though the former was more potent. Cl- removal and pretreatment with bumetanide virtually abolished responses, suggesting that the increase in I(sc) reflected Ca2+ dependent Cl- secretion. Though responses were insensitive to the L-type channel antagonist, verapamil, a marked inhibition was seen in the presence of metal cations (Gd3+, Cd2+, and La3+). Pretreatment with DK-PGD2 inhibited responses to Ca2+ in CPA-primed tissues. Thus, basolateral Ca2+ entry via store-operated Ca2+ channels may be the locus for the inhibitory effects of PGD2 in this tissue. These results could indicate a potential transduction mechanism for the novel DP receptor variously called CRTH2 or DP2.
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Affiliation(s)
- P Larsen
- Royal Danish School of Pharmacy, Universitetsparken 2, DK 2100, Copenhagen, Denmark
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Cuadras MA, Feigelstock DA, An S, Greenberg HB. Gene expression pattern in Caco-2 cells following rotavirus infection. J Virol 2002; 76:4467-82. [PMID: 11932413 PMCID: PMC155077 DOI: 10.1128/jvi.76.9.4467-4482.2002] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rotaviruses are recognized as the leading cause of severe dehydrating diarrhea in infants and young children worldwide. Preventive and therapeutic strategies are urgently needed to fight this pathogen. In tissue culture and in vivo, rotavirus induces structural and functional alterations in the host cell. In order to better understand the molecular mechanisms involved in the events after rotavirus infection, we identified host cellular genes whose mRNA levels changed after infection. For this analysis, we used microarrays containing more than 38,000 human cDNAs to study the transcriptional response of the human intestinal cell line Caco-2 to rotavirus infection. We found that 508 genes were differentially regulated >2-fold at 16 h after rotavirus infection, and only one gene was similarly regulated at 1 h postinfection. Of these transcriptional changes, 73% corresponded to the upregulation of genes, with the majority of them occurring late, at 12 or more hours postinfection. Some of the regulated genes were classified according to known biological function and included genes encoding integral membrane proteins, interferon-regulated genes, transcriptional and translational regulators, and calcium metabolism-related genes. A new picture of global transcriptional regulation in the infected cell is presented and families of genes which may be involved in viral pathogenesis are discussed.
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Affiliation(s)
- Mariela A Cuadras
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
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Brunet JP, Jourdan N, Cotte-Laffitte J, Linxe C, Géniteau-Legendre M, Servin A, Quéro AM. Rotavirus infection induces cytoskeleton disorganization in human intestinal epithelial cells: implication of an increase in intracellular calcium concentration. J Virol 2000; 74:10801-6. [PMID: 11044126 PMCID: PMC110956 DOI: 10.1128/jvi.74.22.10801-10806.2000] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rotavirus infection is the most common cause of severe infantile gastroenteritis worldwide. In vivo, rotavirus exhibits a marked tropism for the differentiated enterocytes of the intestinal epithelium. In vitro, differentiated and undifferentiated intestinal cells can be infected. We observed that rotavirus infection of the human intestinal epithelial Caco-2 cells induces cytoskeleton alterations as a function of cell differentiation. The vimentin network disorganization detected in undifferentiated Caco-2 cells was not found in fully differentiated cells. In contrast, differentiated Caco-2 cells presented Ca(2+)-dependent microtubule disassembly and Ca(2+)-independent cytokeratin 18 rearrangement, which both require viral replication. We propose that these structural alterations could represent the first manifestations of rotavirus-infected enterocyte injury leading to functional perturbations and then to diarrhea.
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Affiliation(s)
- J P Brunet
- Institut National de la Santé et de la Recherche Médicale, Unité 510, Faculté de Pharmacie, Université Paris XI, 92296 Ch atenay-Malabry cedex, France.
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Ruiz MC, Cohen J, Michelangeli F. Role of Ca2+in the replication and pathogenesis of rotavirus and other viral infections. Cell Calcium 2000; 28:137-49. [PMID: 11020376 DOI: 10.1054/ceca.2000.0142] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ca2+ plays a key role in many pathological processes, including viral infections. Rotavirus, the major etiological agent of viral gastroenteritis in children and young animals, provides a useful model to study a number of Ca2+ dependent virus-cell interactions. Rotavirus entry, activation of transcription, morphogenesis, cell lysis, particle release, and the distant action of viral proteins are Ca2+ dependent processes. In the extracellular medium, Ca2+ stabilizes the structure of the viral capsid. During entry into the cell the low cytoplasmic Ca2+ concentration induced the solubilization of the outer protein layer of the capsid and transcriptase activation. Viral protein synthesis modifies Ca2+ homeostasis which, in turn, favours viral morphogenesis and induces cell death. The generation of diarrhea is a multifactorial process involving Ca2+ dependent secretory processes of mediators and water and electrolytes, as well as the induction of cell death in the different cell types that compose the intestinal epithelium. The discovery of the non-structural viral protein NSP4 as a viral enterotoxin and the possible participation of the enteric nervous system in the pathogenesis of diarrhea represent significant advances in its understanding. Ca2+ also plays a role in the replication cycles and pathogenesis of other viral diseases such as poliovirus, Coxsackie virus, cytomegalovirus, vaccinia and measles virus and HIV.
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Affiliation(s)
- M C Ruiz
- Laboratorio de Fisiología Gastrointestinal, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC) Caracas, Venezuela
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Dowling W, Denisova E, LaMonica R, Mackow ER. Selective membrane permeabilization by the rotavirus VP5* protein is abrogated by mutations in an internal hydrophobic domain. J Virol 2000; 74:6368-76. [PMID: 10864647 PMCID: PMC112143 DOI: 10.1128/jvi.74.14.6368-6376.2000] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Rotavirus infectivity is dependent on the proteolytic cleavage of the VP4 spike protein into VP8* and VP5* proteins. Proteolytically activated virus, as well as expressed VP5*, permeabilizes membranes, suggesting that cleavage exposes a membrane-interactive domain of VP5* which effects rapid viral entry. The VP5* protein contains a single long hydrophobic domain (VP5*-HD, residues 385 to 404) at an internal site. In order to address the role of the VP5*-HD in permeabilizing cellular membranes, we analyzed the entry of o-nitrophenyl-beta-D-galactopyranoside (ONPG) into cells induced to express VP5* or mutated VP5* polypeptides. Following IPTG (isopropyl-beta-D-thiogalactopyranoside) induction, VP5* and VP5* truncations containing the VP5*-HD permeabilized cells to the entry and cleavage of ONPG, while VP8* and control proteins had no effect on cellular permeability. Expression of VP5* deletions containing residues 265 to 474 or 265 to 404 permeabilized cells; however, C-terminal truncations which remove the conserved GGA (residues 399 to 401) within the HD abolished membrane permeability. Site-directed mutagenesis of the VP5-HD further demonstrated a requirement for residues within the HD for VP5*-induced membrane permeability. Functional analysis of mutant VP5*s indicate that conserved glycines within the HD are required and suggest that a random coiled structure rather than the strictly hydrophobic character of the domain is required for permeability. Expressed VP5* did not alter bacterial growth kinetics or lyse bacteria following induction. Instead, VP5*-mediated size-selective membrane permeability, releasing 376-Da carboxyfluorescein but not 4-kDa fluorescein isothiocyanate-dextran from preloaded liposomes. These findings suggest that the fundamental role for VP5* in the rotavirus entry process may be to expose triple-layered particles to low [Ca](i), which uncoats the virus, rather than to effect the detergent-like lysis of early endosomal membranes.
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Affiliation(s)
- W Dowling
- Department of Medicine, SUNY at Stony Brook, Stony Brook, New York 11794-8173, USA
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Abstract
Viral gastroenteritis is a major public health problem worldwide, and the number of identified pathogens continuously increases. Investigators have made considerable progress toward understanding both the epidemiology and the mechanisms of virus-cell interactions, host responses, and pathogenesis. A vaccine for the most important pathogen, rotavirus, has been approved by the US Food and Drug Administration, but possible complications have temporarily curbed the use of this vaccine.
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Affiliation(s)
- R D Shaw
- Department of Medicine, Northport VA Medical Center, Northport, New York and Department of Medicine, SUNY at Stony Brook, Stony Brook, New York 11768, USA.
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Abstract
A large number of viruses can be found in the human intestine. Some (bacteriophages) infect the bacteria present as normal flora and others use the gut as a portal of entry. This review examines the virology, pathogenesis, immunology, epidemiology, clinical features, treatment and prevention of the viral enteropathogens. Rotavirus is undoubtedly the most important, causing an estimated 800,000 deaths each year, especially in developing countries. Recently, an oral live quadrivalent rhesus rotavirus vaccine has been licensed for use in the USA. It has great potential but there are a number of hurdles to be overcome before it can be given to infants in developing countries. Molecular techniques are revolutionizing our understanding of rotavirus pathogenesis, and the tremendous diversity of Caliciviridae and Astroviridae, as well as producing new diagnostic techniques and vaccines.
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Affiliation(s)
- C A Hart
- Department of Medical Microbiology and Genitourinary Medicine, University of Liverpool, PO Box 147, Liverpool L69 3GA, UK.
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