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Hung CH, Yen JB, Chang PJ, Chen LW, Huang TY, Tsai WJ, Tsai YC. Characterization of Human Norovirus Nonstructural Protein NS1.2 Involved in the Induction of the Filamentous Endoplasmic Reticulum, Enlarged Lipid Droplets, LC3 Recruitment, and Interaction with NTPase and NS4. Viruses 2023; 15:v15030812. [PMID: 36992520 PMCID: PMC10053803 DOI: 10.3390/v15030812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/09/2023] [Accepted: 03/20/2023] [Indexed: 03/31/2023] Open
Abstract
Human noroviruses (HuNVs) are the leading cause of gastroenteritis worldwide. NS1.2 is critical for HuNV pathogenesis, but the function is still unclear. The GII NS1.2 of HuNVs, unlike GI NS1.2, was localized to the endoplasmic reticulum (ER) and lipid droplets (LDs) and is accompanied by a distorted-filamentous ER morphology and aggregated-enlarged LDs. LC3 was recruited to the NS1.2-localized membrane through an autophagy-independent pathway. NS1.2, expressed from a cDNA clone of GII.4 norovirus, formed complexes with NTPase and NS4, which exhibited aggregated vesicle-like structures that were also colocalized with LC3 and LDs. NS1.2 is structurally divided into three domains from the N terminus: an inherently disordered region (IDR), a region that contains a putative hydrolase with the H-box/NC catalytic center (H-box/NC), and a C-terminal 251-330 a.a. region containing membrane-targeting domain. All three functional domains of NS1.2 were required for the induction of the filamentous ER. The IDR was essential for LC3 recruitment by NS1.2. Both the H-Box/NC and membrane-targeting domains are required for the induction of aggregated-enlarged LDs, NS1.2 self-assembly, and interaction with NTPase. The membrane-targeting domain was sufficient to interact with NS4. The study characterized the NS1.2 domain required for membrane targeting and protein-protein interactions, which are crucial for forming a viral replication complex.
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Affiliation(s)
- Chien-Hui Hung
- Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan 33302, Taiwan
- Department of Internal Medicine, Division of Infectious Diseases, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan
| | - Ju-Bei Yen
- Department of Pediatrics, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan
| | - Pey-Jium Chang
- Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan 33302, Taiwan
| | - Lee-Wen Chen
- Department of Respiratory Care, Chung Gung University of Science and Technology, Chiayi 61363, Taiwan
| | - Tsung-Yu Huang
- Department of Internal Medicine, Division of Infectious Diseases, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan
| | - Wan-Ju Tsai
- Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan 33302, Taiwan
| | - Yu-Chin Tsai
- Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan 33302, Taiwan
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2
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Abstract
Human noroviruses (HuNoVs) are increasingly becoming the main cause of transmissible gastroenteritis worldwide, with hundreds of thousands of deaths recorded annually. Yet, decades after their discovery, there is still no effective treatment or vaccine. Efforts aimed at developing vaccines or treatment will benefit from a greater understanding of norovirus-host interactions, including the host response to infection. In this review, we provide a concise overview of the evidence establishing the significance of type I and type III interferon (IFN) responses in the restriction of noroviruses. We also critically examine our current understanding of the molecular mechanisms of IFN induction in norovirus-infected cells, and outline the diverse strategies deployed by noroviruses to supress and/or avoid host IFN responses. It is our hope that this review will facilitate further discussion and increase interest in this area.
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Affiliation(s)
- Aminu S. Jahun
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
- *Correspondence: Aminu S. Jahun,
| | - Ian G. Goodfellow
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
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3
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Noroviruses-The State of the Art, Nearly Fifty Years after Their Initial Discovery. Viruses 2021; 13:v13081541. [PMID: 34452406 PMCID: PMC8402810 DOI: 10.3390/v13081541] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/06/2021] [Accepted: 07/31/2021] [Indexed: 12/11/2022] Open
Abstract
Human noroviruses are recognised as the major global cause of viral gastroenteritis. Here, we provide an overview of notable advances in norovirus research and provide a short recap of the novel model systems to which much of the recent progress is owed. Significant advances include an updated classification system, the description of alternative virus-like protein morphologies and capsid dynamics, and the further elucidation of the functions and roles of various viral proteins. Important milestones include new insights into cell tropism, host and microbial attachment factors and receptors, interactions with the cellular translational apparatus, and viral egress from cells. Noroviruses have been detected in previously unrecognised hosts and detection itself is facilitated by improved analytical techniques. New potential transmission routes and/or viral reservoirs have been proposed. Recent in vivo and in vitro findings have added to the understanding of host immunity in response to norovirus infection, and vaccine development has progressed to preclinical and even clinical trial testing. Ongoing development of therapeutics includes promising direct-acting small molecules and host-factor drugs.
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4
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Smertina E, Hall RN, Urakova N, Strive T, Frese M. Calicivirus Non-structural Proteins: Potential Functions in Replication and Host Cell Manipulation. Front Microbiol 2021; 12:712710. [PMID: 34335548 PMCID: PMC8318036 DOI: 10.3389/fmicb.2021.712710] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 06/21/2021] [Indexed: 01/15/2023] Open
Abstract
The Caliciviridae are a family of viruses with a single-stranded, non-segmented RNA genome of positive polarity. The ongoing discovery of caliciviruses has increased the number of genera in this family to 11 (Norovirus, Nebovirus, Sapovirus, Lagovirus, Vesivirus, Nacovirus, Bavovirus, Recovirus, Salovirus, Minovirus, and Valovirus). Caliciviruses infect a wide range of hosts that include fishes, amphibians, reptiles, birds, and marine and land mammals. All caliciviruses have a genome that encodes a major and a minor capsid protein, a genome-linked viral protein, and several non-structural proteins. Of these non-structural proteins, only the helicase, protease, and RNA-dependent RNA polymerase share clear sequence and structural similarities with proteins from other virus families. In addition, all caliciviruses express two or three non-structural proteins for which functions have not been clearly defined. The sequence diversity of these non-structural proteins and a multitude of processing strategies suggest that at least some have evolved independently, possibly to counteract innate and adaptive immune responses in a host-specific manner. Studying these proteins is often difficult as many caliciviruses cannot be grown in cell culture. Nevertheless, the study of recombinant proteins has revealed many of their properties, such as intracellular localization, capacity to oligomerize, and ability to interact with viral and/or cellular proteins; the release of non-structural proteins from transfected cells has also been investigated. Here, we will summarize these findings and discuss recent in silico studies that identified previously overlooked putative functional domains and structural features, including transmembrane domains that suggest the presence of viroporins.
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Affiliation(s)
- Elena Smertina
- Commonwealth Scientific and Industrial Research Organization, Health and Biosecurity, Canberra, ACT, Australia
- Faculty of Science and Technology, University of Canberra, Canberra, ACT, Australia
| | - Robyn N. Hall
- Commonwealth Scientific and Industrial Research Organization, Health and Biosecurity, Canberra, ACT, Australia
- Centre for Invasive Species Solutions, Canberra, ACT, Australia
| | - Nadya Urakova
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, Netherlands
| | - Tanja Strive
- Commonwealth Scientific and Industrial Research Organization, Health and Biosecurity, Canberra, ACT, Australia
- Centre for Invasive Species Solutions, Canberra, ACT, Australia
| | - Michael Frese
- Commonwealth Scientific and Industrial Research Organization, Health and Biosecurity, Canberra, ACT, Australia
- Faculty of Science and Technology, University of Canberra, Canberra, ACT, Australia
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5
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Campillay-Véliz CP, Carvajal JJ, Avellaneda AM, Escobar D, Covián C, Kalergis AM, Lay MK. Human Norovirus Proteins: Implications in the Replicative Cycle, Pathogenesis, and the Host Immune Response. Front Immunol 2020; 11:961. [PMID: 32612600 PMCID: PMC7308418 DOI: 10.3389/fimmu.2020.00961] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 04/23/2020] [Indexed: 12/19/2022] Open
Abstract
Human noroviruses (HuNoVs) are the cause of more than 95% of epidemic non-bacterial gastroenteritis worldwide, with some lethal cases. These viral agents affect people of all ages. However, young children and older adults are the highest-risk groups, being affected with the greatest rate of hospitalizations and morbidity cases. HuNoV structural proteins, especially VP1, have been studied extensively. In contrast, the functions of the non-structural proteins of the virus have been undescribed in depth. Studies on HuNoV non-structural proteins have mostly been made by expressing them individually in in vitro cultures, providing insights of their functions and the role that they play in HuNoV replication and pathogenesis. This review examines exhaustively the functions of both HuNoV structural and non-structural proteins and their possible role within the viral replicative cycle and the pathogenesis of the virus. It also highlights recent findings regarding the host's innate and adaptive immune responses against HuNoV, which are of great relevance for diagnostics and vaccine development so as to prevent infections caused by these fastidious viruses.
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Affiliation(s)
- Claudia P Campillay-Véliz
- Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile
| | - Jonatan J Carvajal
- Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile
| | - Andrea M Avellaneda
- Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile
| | - Darling Escobar
- Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile
| | - Camila Covián
- Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad de Chile, Santiago, Chile
| | - Alexis M Kalergis
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad de Chile, Santiago, Chile.,Departamento de Endocrinología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Margarita K Lay
- Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad de Chile, Santiago, Chile
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6
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Yu P, Li Y, Li Y, Miao Z, Peppelenbosch MP, Pan Q. Guanylate-binding protein 2 orchestrates innate immune responses against murine norovirus and is antagonized by the viral protein NS7. J Biol Chem 2020; 295:8036-8047. [PMID: 32354743 DOI: 10.1074/jbc.ra120.013544] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/29/2020] [Indexed: 01/17/2023] Open
Abstract
Noroviruses are the main causative agents of acute viral gastroenteritis, but the host factors that restrict their replication remain poorly identified. Guanylate-binding proteins (GBPs) are interferon (IFN)-inducible GTPases that exert broad antiviral activity and are important mediators of host defenses against viral infections. Here, we show that both IFN-γ stimulation and murine norovirus (MNV) infection induce GBP2 expression in murine macrophages. Results from loss- and gain-of-function assays indicated that GBP2 is important for IFN-γ-dependent anti-MNV activity in murine macrophages. Ectopic expression of MNV receptor (CD300lf) in human HEK293T epithelial cells conferred susceptibility to MNV infection. Importantly, GBP2 potently inhibited MNV in these human epithelial cells. Results from mechanistic dissection experiments revealed that the N-terminal G domain of GBP2 mediates these anti-MNV effects. R48A and K51A substitutions in GBP2, associated with loss of GBP2 GTPase activity, attenuated the anti-MNV effects of GBP2. Finally, we found that nonstructural protein 7 (NS7) of MNV co-localizes with GBP2 and antagonizes the anti-MNV activity of GBP2. These findings reveal that GBP2 is an important mediator of host defenses against murine norovirus.
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Affiliation(s)
- Peifa Yu
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Yang Li
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Yunlong Li
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Zhijiang Miao
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Maikel P Peppelenbosch
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Qiuwei Pan
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
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7
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Hannemann H. Viral replicons as valuable tools for drug discovery. Drug Discov Today 2020; 25:1026-1033. [PMID: 32272194 PMCID: PMC7136885 DOI: 10.1016/j.drudis.2020.03.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/28/2020] [Accepted: 03/13/2020] [Indexed: 12/15/2022]
Abstract
RNA viruses can cause severe diseases such as dengue, Lassa, chikungunya and Ebola. Many of these viruses can only be propagated under high containment levels, necessitating the development of low containment surrogate systems such as subgenomic replicons and minigenome systems. Replicons are self-amplifying recombinant RNA molecules expressing proteins sufficient for their own replication but which do not produce infectious virions. Replicons can persist in cells and are passed on during cell division, enabling quick, efficient and high-throughput testing of drug candidates that act on viral transcription, translation and replication. This review will explore the history and potential for drug discovery of hepatitis C virus, dengue virus, respiratory syncytial virus, Ebola virus and norovirus replicon and minigenome systems.
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Affiliation(s)
- Holger Hannemann
- The Native Antigen Company, Langford Locks, Kidlington OX5 1LH, UK.
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8
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Zhirakovskaia EV, Tikunov AY, Sokolov SN, Kravchuk BI, Krasnova EI, Tikunova NV. Characterization of the complete genome sequence of the recombinant norovirus GII.P16/GII.4_Sydney_2012 revealed in Russia. Vavilovskii Zhurnal Genet Selektsii 2020; 24:69-79. [PMID: 33659783 PMCID: PMC7716542 DOI: 10.18699/vj20.597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Noroviruses (the Caliciviridae family) are a common cause of acute gastroenteritis in all age groups. These small non-envelope viruses with a single-stranded (+)RNA genome are characterized by high genetic variability. Continuous changes in the genetic diversity of co-circulating noroviruses and the emergence of new recombinant variants are observed worldwide. Recently, new recombinant noroviruses with a novel GII.P16 polymerase associated with different capsid proteins VP1 were reported. As a part of the surveillance study of sporadic cases of acute gastroenteritis in Novosibirsk, a total of 46 clinical samples from children with diarrhea were screened in 2016. Norovirus was detected in six samples from hospitalized children by RT-PCR. The identified noroviruses were classified as recombinant variants GII.P21/GII.3, GII. Pe/GII.4_Sydney_2012, and GII.P16/GII.4_Sydney_2012 by sequencing of the ORF1/ORF2 junction. In Novosibirsk, the first appearance of the new recombinant genotype GII.P16/ GII.4_Sydney_2012 was recorded in spring 2016. Before this study, only four complete genome sequences of the Russian GII.P16/GII.3 norovirus strains were available in the GenBank database. In this work, the complete genome sequence of the Russian strain Hu/GII.P16-GII.4/RUS/Novosibirsk/NS16-C38/2016 (GenBank KY210980) was determined. A comparison of the nucleotide and the deduced amino acid sequences showed a high homology of the Russian strain with GII.P16/GII.4_Sydney_2012 strains from other parts of the world. A comparative analysis showed that several unique substitutions occurred in the GII.P16 polymerase, N-terminal p48 protein, and minor capsid protein VP2 genes, while no unique changes in the capsid VP1 gene were observed. A functional significance of these changes suggests that a wide distribution of the strains with the novel GII.P16 polymerase may be associated both with several amino acid substitutions in the polymerase active center and with the insertion of glutamic acid or glycine in an N-terminal p48 protein that blocks the secretory immunity of intestinal epithelial cells. Further monitoring of genotypes will allow determining the distribution of norovirus recombinants with the polymerase GII.P16 in Russia.
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Affiliation(s)
- E V Zhirakovskaia
- Institute of Сhemical Biology аnd Fundamental Medicine of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - A Y Tikunov
- Institute of Сhemical Biology аnd Fundamental Medicine of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - S N Sokolov
- Institute of Сhemical Biology аnd Fundamental Medicine of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia State Research Center of Virology and Biotechnology Vector, Koltsovo, Novosibirsk region, Russia
| | - B I Kravchuk
- Institute of Сhemical Biology аnd Fundamental Medicine of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - E I Krasnova
- Novosibirsk State Medical University, Department of Infectious Diseases, Novosibirsk, Russia
| | - N V Tikunova
- Institute of Сhemical Biology аnd Fundamental Medicine of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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9
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Murakami K, Tenge VR, Karandikar UC, Lin SC, Ramani S, Ettayebi K, Crawford SE, Zeng XL, Neill FH, Ayyar BV, Katayama K, Graham DY, Bieberich E, Atmar RL, Estes MK. Bile acids and ceramide overcome the entry restriction for GII.3 human norovirus replication in human intestinal enteroids. Proc Natl Acad Sci U S A 2020; 117:1700-1710. [PMID: 31896578 PMCID: PMC6983410 DOI: 10.1073/pnas.1910138117] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Human noroviruses (HuNoVs) cause sporadic and epidemic outbreaks of gastroenteritis in all age groups worldwide. We previously reported that stem cell-derived human intestinal enteroid (HIE) cultures support replication of multiple HuNoV strains and that some strains (e.g., GII.3) replicate only in the presence of bile. Heat- and trypsin-treatment of bile did not reduce GII.3 replication, indicating a nonproteinaceous component in bile functions as an active factor. Here we show that bile acids (BAs) are critical for GII.3 replication and replication correlates with BA hydrophobicity. Using the highly effective BA, glycochenodeoxycholic acid (GCDCA), we show BAs act during the early stage of infection, BA-dependent replication in HIEs is not mediated by detergent effects or classic farnesoid X receptor or Takeda G protein-coupled receptor 5 signaling but involves another G protein-coupled receptor, sphingosine-1-phosphate receptor 2, and BA treatment of HIEs increases particle uptake. We also demonstrate that GCDCA induces multiple cellular responses that promote GII.3 replication in HIEs, including enhancement of 1) endosomal uptake, 2) endosomal acidification and subsequent activity of endosomal/lysosomal enzyme acid sphingomyelinase (ASM), and 3) ceramide levels on the apical membrane. Inhibitors of endosomal acidification or ASM reduce GII.3 infection and exogenous addition of ceramide alone permits infection. Furthermore, inhibition of lysosomal exocytosis of ASM, which is required for ceramide production at the apical surface, decreases GII.3 infection. Together, our results support a model where GII.3 exploits rapid BA-mediated cellular endolysosomal dynamic changes and cellular ceramide to enter and replicate in jejunal HIEs.
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Affiliation(s)
- Kosuke Murakami
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
- Department of Virology II, National Institute of Infectious Diseases, Musashi-murayama, Tokyo 208-0011, Japan
| | - Victoria R Tenge
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Umesh C Karandikar
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Shih-Ching Lin
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Sasirekha Ramani
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Khalil Ettayebi
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Sue E Crawford
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Xi-Lei Zeng
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Frederick H Neill
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - B Vijayalakshmi Ayyar
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Kazuhiko Katayama
- Department of Virology II, National Institute of Infectious Diseases, Musashi-murayama, Tokyo 208-0011, Japan
- Laboratory of Viral Infection I, Kitasato Institute for Life Sciences, Kitasato University, Tokyo 108-8641, Japan
| | - David Y Graham
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
- Department of Medicine, Michael E. DeBakey VA Medical Center, Houston, TX 77030
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030
| | - Erhard Bieberich
- Department of Physiology, University of Kentucky, Lexington, KY 40506
| | - Robert L Atmar
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030;
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030
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10
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Peñaflor-Téllez Y, Trujillo-Uscanga A, Escobar-Almazán JA, Gutiérrez-Escolano AL. Immune Response Modulation by Caliciviruses. Front Immunol 2019; 10:2334. [PMID: 31632406 PMCID: PMC6779827 DOI: 10.3389/fimmu.2019.02334] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 09/16/2019] [Indexed: 12/29/2022] Open
Abstract
Noroviruses and Sapoviruses, classified in the Caliciviridae family, are small positive-stranded RNA viruses, considered nowadays the leading cause of acute gastroenteritis globally in both children and adults. Although most noroviruses have been associated with gastrointestinal disease in humans, almost 50 years after its discovery, there is still a lack of comprehensive evidence regarding its biology and pathogenesis mainly because they can be neither conveniently grown in cultured cells nor propagated in animal models. However, other members of this family such as Feline calicivirus (FCV), Murine norovirus (MNV), Rabbit hemorrhagic disease virus (RHDV), and Porcine sapovirus (PS), from which there are accessible propagation systems, have been useful to study the calicivirus replication strategies. Using cell cultures and animal models, many of the functions of the viral proteins in the viral replication cycles have been well-characterized. Moreover, evidence of the role of viral proteins from different members of the family in the establishment of infection has been generated and the mechanism of their immunopathogenesis begins to be understood. In this review, we discuss different aspects of how caliciviruses are implicated in membrane rearrangements, apoptosis, and evasion of the immune responses, highlighting some of the pathogenic mechanisms triggered by different members of the Caliciviridae family.
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Affiliation(s)
- Yoatzin Peñaflor-Téllez
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados, IPN, Mexico City, Mexico
| | - Adrian Trujillo-Uscanga
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados, IPN, Mexico City, Mexico
| | - Jesús Alejandro Escobar-Almazán
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados, IPN, Mexico City, Mexico
| | - Ana Lorena Gutiérrez-Escolano
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados, IPN, Mexico City, Mexico
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11
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Neil JA, Matsuzawa-Ishimoto Y, Kernbauer-Hölzl E, Schuster SL, Sota S, Venzon M, Dallari S, Galvao Neto A, Hine A, Hudesman D, Loke P, Nice TJ, Cadwell K. IFN-I and IL-22 mediate protective effects of intestinal viral infection. Nat Microbiol 2019; 4:1737-1749. [PMID: 31182797 PMCID: PMC6871771 DOI: 10.1038/s41564-019-0470-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 04/26/2019] [Indexed: 02/07/2023]
Abstract
Products derived from bacterial members of the gut microbiota evoke immune signalling pathways of the host that promote immunity and barrier function in the intestine. How immune reactions to enteric viruses support intestinal homeostasis is unknown. We recently demonstrated that infection by murine norovirus (MNV) reverses intestinal abnormalities following depletion of bacteria, indicating that an intestinal animal virus can provide cues to the host that are typically attributed to the microbiota. Here, we elucidate mechanisms by which MNV evokes protective responses from the host. We identify an important role for the viral protein NS1/2 in establishing local replication and a type I interferon (IFN-I) response in the colon. We further show that IFN-I acts on intestinal epithelial cells to increase the proportion of CCR2-dependent macrophages and interleukin (IL)-22-producing innate lymphoid cells, which in turn promote pSTAT3 signalling in intestinal epithelial cells and protection from intestinal injury. In addition, we demonstrate that MNV provides a striking IL-22-dependent protection against early-life lethal infection by Citrobacter rodentium. These findings demonstrate novel ways in which a viral member of the microbiota fortifies the intestinal barrier during chemical injury and infectious challenges.
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Affiliation(s)
- Jessica A Neil
- Kimmel Center for Biology and Medicine, Skirball Institute of Biomedical Medicine, New York University School of Medicine, New York, NY, USA
| | - Yu Matsuzawa-Ishimoto
- Kimmel Center for Biology and Medicine, Skirball Institute of Biomedical Medicine, New York University School of Medicine, New York, NY, USA
| | - Elisabeth Kernbauer-Hölzl
- Kimmel Center for Biology and Medicine, Skirball Institute of Biomedical Medicine, New York University School of Medicine, New York, NY, USA
| | - Samantha L Schuster
- Kimmel Center for Biology and Medicine, Skirball Institute of Biomedical Medicine, New York University School of Medicine, New York, NY, USA
| | - Stela Sota
- Kimmel Center for Biology and Medicine, Skirball Institute of Biomedical Medicine, New York University School of Medicine, New York, NY, USA
- Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
| | - Mericien Venzon
- Kimmel Center for Biology and Medicine, Skirball Institute of Biomedical Medicine, New York University School of Medicine, New York, NY, USA
- Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
| | - Simone Dallari
- Kimmel Center for Biology and Medicine, Skirball Institute of Biomedical Medicine, New York University School of Medicine, New York, NY, USA
| | - Antonio Galvao Neto
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Ashley Hine
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
- Department of Medicine, Division of Gastroenterology, New York University School of Medicine, New York, NY, USA
| | - David Hudesman
- Department of Medicine, Division of Gastroenterology, New York University School of Medicine, New York, NY, USA
| | - P'ng Loke
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Timothy J Nice
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR, USA
| | - Ken Cadwell
- Kimmel Center for Biology and Medicine, Skirball Institute of Biomedical Medicine, New York University School of Medicine, New York, NY, USA.
- Department of Microbiology, New York University School of Medicine, New York, NY, USA.
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12
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Arthur SE, Sorgeloos F, Hosmillo M, Goodfellow IG. Epigenetic Suppression of Interferon Lambda Receptor Expression Leads to Enhanced Human Norovirus Replication In Vitro. mBio 2019; 10:e02155-19. [PMID: 31575769 PMCID: PMC6775457 DOI: 10.1128/mbio.02155-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 12/16/2022] Open
Abstract
Human norovirus (HuNoV) is the main cause of gastroenteritis worldwide, yet no therapeutics are currently available. Here, we utilize a human norovirus replicon in human gastric tumor (HGT) cells to identify host factors involved in promoting or inhibiting HuNoV replication. We observed that an interferon (IFN)-cured population of replicon-harboring HGT cells (HGT-Cured) was enhanced in their ability to replicate transfected HuNoV RNA compared to parental HGT cells, suggesting that differential gene expression in HGT-Cured cells created an environment favoring norovirus replication. Microarrays were used to identify genes differentially regulated in HGT-NV and HGT-Cured compared to parental cells. We found that IFN lambda receptor (IFNLR1) expression was highly reduced in HGT-NV and HGT-Cured cells. While all three cell lines responded to exogenous IFN-β by inducing interferon-stimulated genes, HGT-NV and HGT-Cured cells failed to respond to exogenous IFN-λ. Methylation-sensitive PCR showed that an increased methylation of the IFNLR1 promoter and inhibition of DNA methyltransferase activity partially reactivated IFNLR1 expression in HGT-NV and HGT-Cured cells, indicating that host adaptation occurred via epigenetic reprogramming. Moreover, IFNLR1 ectopic expression rescued response to IFN-λ and restricted HuNoV replication in HGT-NV cells. We conclude that type III IFN is important in inhibiting HuNoV replication in vitro and that the loss of IFNLR1 enhances replication of HuNoV. This study unravels for the first time epigenetic reprogramming of the interferon lambda receptor as a new mechanism of cellular adaptation during long-term RNA virus replication and shows that an endogenous level of interferon lambda signaling is able to control human norovirus replication.IMPORTANCE Noroviruses are one of the most widespread causes of gastroenteritis, yet no suitable therapeutics are available for their control. Moreover, to date, knowledge of the precise cellular processes that control the replication of the human norovirus remains ill defined. Recent work has highlighted the importance of type III interferon (IFN) responses in the restriction of viruses that infect the intestine. Here, we analyzed the adaptive changes required to support long-term replication of noroviruses in cell culture and found that the receptor for type III IFN is decreased in its expression. We confirmed that this decreased expression was driven by epigenetic modifications and that cells lacking the type III IFN receptor are more permissive for norovirus replication. This work provides new insights into key host-virus interactions required for the control of noroviruses and opens potential novel avenues for their therapeutic control.
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Affiliation(s)
- Sabastine E Arthur
- Division of Virology, Department of Pathology, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Frédéric Sorgeloos
- Division of Virology, Department of Pathology, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Myra Hosmillo
- Division of Virology, Department of Pathology, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Ian G Goodfellow
- Division of Virology, Department of Pathology, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
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13
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Strtak AC, Perry JL, Sharp MN, Chang-Graham AL, Farkas T, Hyser JM. Recovirus NS1-2 Has Viroporin Activity That Induces Aberrant Cellular Calcium Signaling To Facilitate Virus Replication. mSphere 2019; 4:e00506-19. [PMID: 31533997 PMCID: PMC6751491 DOI: 10.1128/msphere.00506-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 08/30/2019] [Indexed: 02/07/2023] Open
Abstract
Enteric viruses in the Caliciviridae family cause acute gastroenteritis in humans and animals, but the cellular processes needed for virus replication and disease remain unknown. A common strategy among enteric viruses, including rotaviruses and enteroviruses, is to encode a viral ion channel (i.e., viroporin) that is targeted to the endoplasmic reticulum (ER) and disrupts host calcium (Ca2+) homeostasis. Previous reports have demonstrated genetic and functional similarities between the nonstructural proteins of caliciviruses and enteroviruses, including the calicivirus NS1-2 protein and the 2B viroporin of enteroviruses. However, it is unknown whether caliciviruses alter Ca2+ homeostasis for virus replication or whether the NS1-2 protein has viroporin activity like its enterovirus counterpart. To address these questions, we used Tulane virus (TV), a rhesus enteric calicivirus, to examine Ca2+ signaling during infection and determine whether NS1-2 has viroporin activity that disrupts Ca2+ homeostasis. We found that TV increases Ca2+ signaling during infection and that increased cytoplasmic Ca2+ levels are important for efficient replication. Further, TV NS1-2 localizes to the endoplasmic reticulum, the predominant intracellular Ca2+ store, and the NS2 region has characteristics of a viroporin domain (VPD). NS1-2 had viroporin activity in a classic bacterial functional assay and caused aberrant Ca2+ signaling when expressed in mammalian cells, but truncation of the VPD abrogated these activities. Together, our data provide new mechanistic insights into the function of the NS2 region of NS1-2 and support the premise that enteric viruses, including those within Caliciviridae, exploit host Ca2+ signaling to facilitate their replication.IMPORTANCE Tulane virus is one of many enteric caliciviruses that cause acute gastroenteritis and diarrheal disease. Globally, enteric caliciviruses affect both humans and animals and amass >65 billion dollars per year in treatment and health care-associated costs, thus imposing an enormous economic burden. Recent progress has resulted in several cultivation systems (B cells, enteroids, and zebrafish larvae) to study human noroviruses, but mechanistic insights into the viral factors and host pathways important for enteric calicivirus replication and infection are still largely lacking. Here, we used Tulane virus, a calicivirus that is biologically similar to human noroviruses and can be cultivated by conventional cell culture, to identify and functionally validate NS1-2 as an enteric calicivirus viroporin. Viroporin-mediated calcium signaling may be a broadly utilized pathway for enteric virus replication, and its existence within caliciviruses provides a novel approach to developing antivirals and comprehensive therapeutics for enteric calicivirus diarrheal disease outbreaks.
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Affiliation(s)
- Alicia C Strtak
- Alkek Center for Metagenomic and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Jacob L Perry
- Alkek Center for Metagenomic and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Mark N Sharp
- Alkek Center for Metagenomic and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- Texas Medical Center Summer Research Internship Program, Augustana College, Rock Island, Illinois, USA
| | - Alexandra L Chang-Graham
- Alkek Center for Metagenomic and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Tibor Farkas
- Department of Pathobiological Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, Louisiana, USA
- Louisiana Animal Disease Diagnostic Laboratory, Baton Rouge, Louisiana, USA
| | - Joseph M Hyser
- Alkek Center for Metagenomic and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
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14
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Smertina E, Urakova N, Strive T, Frese M. Calicivirus RNA-Dependent RNA Polymerases: Evolution, Structure, Protein Dynamics, and Function. Front Microbiol 2019; 10:1280. [PMID: 31244803 PMCID: PMC6563846 DOI: 10.3389/fmicb.2019.01280] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/22/2019] [Indexed: 12/11/2022] Open
Abstract
The Caliciviridae are viruses with a positive-sense, single-stranded RNA genome that is packaged into an icosahedral, environmentally stable protein capsid. The family contains five genera (Norovirus, Nebovirus, Sapovirus, Lagovirus, and Vesivirus) that infect vertebrates including amphibians, reptiles, birds, and mammals. The RNA-dependent RNA polymerase (RdRp) replicates the genome of RNA viruses and can speed up evolution due to its error-prone nature. Studying calicivirus RdRps in the context of genuine virus replication is often hampered by a lack of suitable model systems. Enteric caliciviruses and RHDV in particular are notoriously difficult to propagate in cell culture; therefore, molecular studies of replication mechanisms are challenging. Nevertheless, research on recombinant proteins has revealed several unexpected characteristics of calicivirus RdRps. For example, the RdRps of RHDV and related lagoviruses possess the ability to expose a hydrophobic motif, to rearrange Golgi membranes, and to copy RNA at unusually high temperatures. This review is focused on the structural dynamics, biochemical properties, kinetics, and putative interaction partners of these RdRps. In addition, we discuss the possible existence of a conserved but as yet undescribed structural element that is shared amongst the RdRps of all caliciviruses.
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Affiliation(s)
- Elena Smertina
- Commonwealth Scientific and Industrial Research Organisation, Health and Biosecurity, Canberra, ACT, Australia
- Faculty of Science and Technology, University of Canberra, Canberra, ACT, Australia
| | - Nadya Urakova
- Department of Entomology, Pennsylvania State University, University Park, PA, United States
| | - Tanja Strive
- Commonwealth Scientific and Industrial Research Organisation, Health and Biosecurity, Canberra, ACT, Australia
- Invasive Animals Cooperative Research Centre, University of Canberra, Canberra, ACT, Australia
| | - Michael Frese
- Faculty of Science and Technology, University of Canberra, Canberra, ACT, Australia
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15
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Genomics Analyses of GIV and GVI Noroviruses Reveal the Distinct Clustering of Human and Animal Viruses. Viruses 2019; 11:v11030204. [PMID: 30823663 PMCID: PMC6466045 DOI: 10.3390/v11030204] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 02/23/2019] [Accepted: 02/25/2019] [Indexed: 01/23/2023] Open
Abstract
Noroviruses are highly diverse viruses that are the major viral cause of acute gastroenteritis in humans. Although these viruses can infect multiple mammalian species, their potential for zoonosis is not well understood, especially within Genogroup IV (GIV), which contains viruses that infect humans, canines, and felines. The study of GIV viruses has been, in part, hindered by the limited number of complete genomes. Here, we developed a full-genome amplicon-based platform that facilitated the sequencing of canine noroviruses circulating in the United States. Eight novel nearly full-length canine norovirus genomes and two nearly complete VP1 sequences, including four GIV.2, three GVI.1, and three GVI.2 viruses, were successfully obtained. Only animal strains exhibited GVI/GIV chimeric viruses, demonstrating restrictions in norovirus recombination. Using genomic, phylogenetic, and structural analyses, we show that differences within the major capsid protein and the non-structural proteins of GIV and GVI noroviruses could potentially limit cross-species transmission between humans, canines, and felines.
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16
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Glingston RS, Deb R, Kumar S, Nagotu S. Organelle dynamics and viral infections: at cross roads. Microbes Infect 2018; 21:20-32. [PMID: 29953921 PMCID: PMC7110583 DOI: 10.1016/j.micinf.2018.06.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 01/12/2023]
Abstract
Viruses are obligate intracellular parasites of the host cells. A commonly accepted view is the requirement of internal membranous structures for various aspects of viral life cycle. Organelles enable favourable intracellular environment for several viruses. However, studies reporting organelle dynamics upon viral infections are scant. In this review, we aim to summarize and highlight modulations caused to various organelles upon viral infection or expression of its proteins.
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Affiliation(s)
- R Sahaya Glingston
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Rachayeeta Deb
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Sachin Kumar
- Viral Immunology Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
| | - Shirisha Nagotu
- Organelle Biology and Cellular Ageing Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
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17
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Subcellular Localization and Functional Characterization of GII.4 Norovirus-Encoded NTPase. J Virol 2018; 92:JVI.01824-17. [PMID: 29212938 PMCID: PMC5809722 DOI: 10.1128/jvi.01824-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 11/29/2017] [Indexed: 12/27/2022] Open
Abstract
The genotype II.4 (GII.4) variants of human noroviruses (HuNVs) are recognized as the major agent of global gastroenteritis outbreaks. Due to the lack of an efficient cell culture system for HuNV propagation, the exact roles of HuNV-encoded nonstructural proteins (including Nterm, NTPase, P22, VPg, Pro, and RdRp) in viral replication or pathogenesis have not yet been fully understood. Here, we report the molecular characterization of the GII.4 HuNV-encoded NTPase (designated GII-NTPase). Results from our studies showed that GII-NTPase forms vesicular or nonvesicular textures in the cell cytoplasm, and the nonvesicular fraction of GII-NTPase significantly localizes to the endoplasmic reticulum (ER) or mitochondria. Deletion analysis revealed that the N-terminal 179-amino-acid (aa) region of GII-NTPase is required for vesicle formation and for ER colocalization, whereas the C-terminal region is involved in mitochondrial colocalization. In particular, two mitochondrion-targeting domains were identified in the C-terminal region of GII-NTPase which perfectly colocalized with mitochondria when the N-terminal region of GII-NTPase was deleted. However, the corresponding C-terminal portions of NTPase derived from the GI HuNV did not show mitochondrial colocalization. We also found that GII-NTPase physically interacts with itself as well as with Nterm and P22, but not VPg, Pro, and RdRp, in cells. The Nterm- and P22-interacting region was mapped to the N-terminal 179-aa region of GII-NTPase, whereas the self-assembly of GII-NTPase could be achieved via a head-to-head, tail-to-tail, or head-to-tail configuration. More importantly, we demonstrate that GII-NTPase possesses a proapoptotic activity, which can be further enhanced by coexpression with Nterm or P22. IMPORTANCE Despite the importance of human norovirus GII.4 variants in global gastroenteritis outbreaks, the basic biological functions of the viral nonstructural proteins in cells remain rarely investigated. In this report, we focus our studies on characteristics of the GII.4 norovirus-encoded NTPase (GII-NTPase). We unexpectedly find that GII-NTPase can perfectly colocalize with mitochondria after its N-terminal region is deleted. However, such a phenomenon is not observed for NTPase encoded by a GI strain. We further reveal that the N-terminal 179-aa region of GII-NTPase is sufficient to mediate (i) vesicle formation, (ii) ER colocalization, (iii) the interaction with two other nonstructural proteins, including Nterm and P22, (iv) the formation of homodimers or homo-oligomers, and (v) the induction of cell apoptosis. Taken together, our findings emphasize that the virus-encoded NTPase must have multiple activities during viral replication or pathogenesis; however, these activities may vary somewhat among different genogroups.
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18
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Doerflinger SY, Cortese M, Romero-Brey I, Menne Z, Tubiana T, Schenk C, White PA, Bartenschlager R, Bressanelli S, Hansman GS, Lohmann V. Membrane alterations induced by nonstructural proteins of human norovirus. PLoS Pathog 2017; 13:e1006705. [PMID: 29077760 PMCID: PMC5678787 DOI: 10.1371/journal.ppat.1006705] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 11/08/2017] [Accepted: 10/20/2017] [Indexed: 01/09/2023] Open
Abstract
Human noroviruses (huNoV) are the most frequent cause of non-bacterial acute gastroenteritis worldwide, particularly genogroup II genotype 4 (GII.4) variants. The viral nonstructural (NS) proteins encoded by the ORF1 polyprotein induce vesical clusters harboring the viral replication sites. Little is known so far about the ultrastructure of these replication organelles or the contribution of individual NS proteins to their biogenesis. We compared the ultrastructural changes induced by expression of norovirus ORF1 polyproteins with those induced upon infection with murine norovirus (MNV). Characteristic membrane alterations induced by ORF1 expression resembled those found in MNV infected cells, consisting of vesicle accumulations likely built from the endoplasmic reticulum (ER) which included single membrane vesicles (SMVs), double membrane vesicles (DMVs) and multi membrane vesicles (MMVs). In-depth analysis using electron tomography suggested that MMVs originate through the enwrapping of SMVs with tubular structures similar to mechanisms reported for picornaviruses. Expression of GII.4 NS1-2, NS3 and NS4 fused to GFP revealed distinct membrane alterations when analyzed by correlative light and electron microscopy. Expression of NS1-2 induced proliferation of smooth ER membranes forming long tubular structures that were affected by mutations in the active center of the putative NS1-2 hydrolase domain. NS3 was associated with ER membranes around lipid droplets (LDs) and induced the formation of convoluted membranes, which were even more pronounced in case of NS4. Interestingly, NS4 was the only GII.4 protein capable of inducing SMV and DMV formation when expressed individually. Our work provides the first ultrastructural analysis of norovirus GII.4 induced vesicle clusters and suggests that their morphology and biogenesis is most similar to picornaviruses. We further identified NS4 as a key factor in the formation of membrane alterations of huNoV and provide models of the putative membrane topologies of NS1-2, NS3 and NS4 to guide future studies. Positive-strand RNA viruses induce membrane alterations harboring the viral replication complexes. In the case of human noroviruses (huNoV), the major cause of acute viral gastroenteritis, these are induced by the ORF1 polyprotein, which is post-translationally processed into the functional nonstructural (NS) proteins. Partly due to the lack of efficient cell culture models, little is known so far about membrane alterations induced by huNoV belonging to the most clinically relevant genogroup II, genotype 4 (GII.4), nor about the function of individual NS proteins in their formation. We therefore expressed ORF1 proteins of GII.4 and individual NS proteins in cells to study their contribution to viral replication complex formation. Expression of ORF1 proteins of GII.4 induced vesicular membrane alterations comparable to those found in infected cells and similar to picornaviruses and hepatitis C virus (HCV). GII.4 NS1-2, NS3 and NS4 are contributing to viral membrane alterations. Our work provides new insights into their function in huNoV induced replication complex formation while identifying NS4 as the most important single determinant. This knowledge might provide novel attractive targets for future therapies inhibiting the formation of the membranous viral replication complex, as exemplified by the efficacy of HCV NS5A inhibitors.
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Affiliation(s)
- Sylvie Y. Doerflinger
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany
- Schaller Research Group at the University of Heidelberg and the DKFZ, Heidelberg, Germany
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, Heidelberg, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, Heidelberg, Germany
| | - Inés Romero-Brey
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, Heidelberg, Germany
| | - Zach Menne
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, Heidelberg, Germany
| | - Thibault Tubiana
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris Sud, Université Paris-Saclay, Gif sur Yvette cedex, France
| | - Christian Schenk
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, Heidelberg, Germany
| | - Peter A. White
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, Australia
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, Heidelberg, Germany
- German Center for Infection Research (DZIF), Heidelberg University, Heidelberg, Germany
| | - Stéphane Bressanelli
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris Sud, Université Paris-Saclay, Gif sur Yvette cedex, France
| | - Grant S. Hansman
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany
- Schaller Research Group at the University of Heidelberg and the DKFZ, Heidelberg, Germany
| | - Volker Lohmann
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 345, Heidelberg, Germany
- * E-mail:
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19
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Schwensow NI, Detering H, Pederson S, Mazzoni C, Sinclair R, Peacock D, Kovaliski J, Cooke B, Fickel J, Sommer S. Resistance to RHD virus in wild Australian rabbits: Comparison of susceptible and resistant individuals using a genomewide approach. Mol Ecol 2017; 26:4551-4561. [PMID: 28667769 DOI: 10.1111/mec.14228] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 06/02/2017] [Accepted: 06/12/2017] [Indexed: 12/20/2022]
Abstract
Deciphering the genes involved in disease resistance is essential if we are to understand host-pathogen coevolutionary processes. The rabbit haemorrhagic disease virus (RHDV) was imported into Australia in 1995 as a biocontrol agent to manage one of the most successful and devastating invasive species, the European rabbit (Oryctolagus cuniculus). During the first outbreaks of the disease, RHDV caused mortality rates of up to 97%. Recently, however, increased genetic resistance to RHDV has been reported. Here, we have aimed to identify genomic differences between rabbits that survived a natural infection with RHDV and those that died in the field using a genomewide next-generation sequencing (NGS) approach. We detected 72 SNPs corresponding to 133 genes associated with survival of a RHD infection. Most of the identified genes have known functions in virus infections and replication, immune responses or apoptosis, or have previously been found to be regulated during RHD. Some of the genes identified in experimental studies, however, did not seem to play a role under natural selection regimes, highlighting the importance of field studies to complement the genomic background of wildlife diseases. Our study provides a set of candidate markers as a tool for the future scanning of wild rabbits for their resistance to RHDV. This is important both for wild rabbit populations in southern Europe where RHD is regarded as a serious problem decimating the prey of endangered predator species and for assessing the success of currently planned RHDV variant biocontrol releases in Australia.
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Affiliation(s)
- Nina I Schwensow
- Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Ulm, Germany.,School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Harald Detering
- Berlin Center for Genomics in Biodiversity Research, Berlin, Germany.,Department of Biochemistry, Genetics and Immunology and Biomedical Research Center (CINBIO), University of Vigo, Vigo, Spain
| | - Stephen Pederson
- Bioinformatics Hub, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Camila Mazzoni
- Berlin Center for Genomics in Biodiversity Research, Berlin, Germany.,Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research (IZW), Berlin, Germany
| | - Ron Sinclair
- School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | | | | | - Brian Cooke
- Institute for Applied Ecology, University of Canberra, Canberra, ACT, Australia
| | - Jörns Fickel
- Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research (IZW), Berlin, Germany.,Molecular Ecology & Evolution, Institute for Biochemistry and Biology, Potsdam University, Potsdam, Germany
| | - Simone Sommer
- Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Ulm, Germany
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20
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Noroviruses Co-opt the Function of Host Proteins VAPA and VAPB for Replication via a Phenylalanine-Phenylalanine-Acidic-Tract-Motif Mimic in Nonstructural Viral Protein NS1/2. mBio 2017; 8:mBio.00668-17. [PMID: 28698274 PMCID: PMC5513711 DOI: 10.1128/mbio.00668-17] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The Norovirus genus contains important human pathogens, but the role of host pathways in norovirus replication is largely unknown. Murine noroviruses provide the opportunity to study norovirus replication in cell culture and in small animals. The human norovirus nonstructural protein NS1/2 interacts with the host protein VAMP-associated protein A (VAPA), but the significance of the NS1/2-VAPA interaction is unexplored. Here we report decreased murine norovirus replication in VAPA- and VAPB-deficient cells. We characterized the role of VAPA in detail. VAPA was required for the efficiency of a step(s) in the viral replication cycle after entry of viral RNA into the cytoplasm but before the synthesis of viral minus-sense RNA. The interaction of VAPA with viral NS1/2 proteins is conserved between murine and human noroviruses. Murine norovirus NS1/2 directly bound the major sperm protein (MSP) domain of VAPA through its NS1 domain. Mutations within NS1 that disrupted interaction with VAPA inhibited viral replication. Structural analysis revealed that the viral NS1 domain contains a mimic of the phenylalanine–phenylalanine-acidic-tract (FFAT) motif that enables host proteins to bind to the VAPA MSP domain. The NS1/2-FFAT mimic region interacted with the VAPA-MSP domain in a manner similar to that seen with bona fide host FFAT motifs. Amino acids in the FFAT mimic region of the NS1 domain that are important for viral replication are highly conserved across murine norovirus strains. Thus, VAPA interaction with a norovirus protein that functionally mimics host FFAT motifs is important for murine norovirus replication. Human noroviruses are a leading cause of gastroenteritis worldwide, but host factors involved in norovirus replication are incompletely understood. Murine noroviruses have been studied to define mechanisms of norovirus replication. Here we defined the importance of the interaction between the hitherto poorly studied NS1/2 norovirus protein and the VAPA host protein. The NS1/2-VAPA interaction is conserved between murine and human noroviruses and was important for early steps in murine norovirus replication. Using structure-function analysis, we found that NS1/2 contains a short sequence that molecularly mimics the FFAT motif that is found in multiple host proteins that bind VAPA. This represents to our knowledge the first example of functionally important mimicry of a host FFAT motif by a microbial protein.
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Emmott E, Sorgeloos F, Caddy SL, Vashist S, Sosnovtsev S, Lloyd R, Heesom K, Locker N, Goodfellow I. Norovirus-Mediated Modification of the Translational Landscape via Virus and Host-Induced Cleavage of Translation Initiation Factors. Mol Cell Proteomics 2017; 16:S215-S229. [PMID: 28087593 PMCID: PMC5393397 DOI: 10.1074/mcp.m116.062448] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 01/12/2017] [Indexed: 11/25/2022] Open
Abstract
Noroviruses produce viral RNAs lacking a 5' cap structure and instead use a virus-encoded viral protein genome-linked (VPg) protein covalently linked to viral RNA to interact with translation initiation factors and drive viral protein synthesis. Norovirus infection results in the induction of the innate response leading to interferon stimulated gene (ISG) transcription. However, the translation of the induced ISG mRNAs is suppressed. A SILAC-based mass spectrometry approach was employed to analyze changes to protein abundance in both whole cell and m7GTP-enriched samples to demonstrate that diminished host mRNA translation correlates with changes to the composition of the eukaryotic initiation factor complex. The suppression of host ISG translation correlates with the activity of the viral protease (NS6) and the activation of cellular caspases leading to the establishment of an apoptotic environment. These results indicate that noroviruses exploit the differences between viral VPg-dependent and cellular cap-dependent translation in order to diminish the host response to infection.
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Affiliation(s)
- Edward Emmott
- From the ‡Division of Virology, Department of Pathology, University of Cambridge, Addenbrookes Hospital, Hills Road, Cambridge, UK;
| | - Frederic Sorgeloos
- From the ‡Division of Virology, Department of Pathology, University of Cambridge, Addenbrookes Hospital, Hills Road, Cambridge, UK
| | - Sarah L Caddy
- From the ‡Division of Virology, Department of Pathology, University of Cambridge, Addenbrookes Hospital, Hills Road, Cambridge, UK
| | - Surender Vashist
- From the ‡Division of Virology, Department of Pathology, University of Cambridge, Addenbrookes Hospital, Hills Road, Cambridge, UK
| | - Stanislav Sosnovtsev
- §Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Richard Lloyd
- ¶Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX
| | - Kate Heesom
- ‖Proteomics facility, School of Biochemistry, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK
| | - Nicolas Locker
- **Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, UK
| | - Ian Goodfellow
- From the ‡Division of Virology, Department of Pathology, University of Cambridge, Addenbrookes Hospital, Hills Road, Cambridge, UK;
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Identification of Human Junctional Adhesion Molecule 1 as a Functional Receptor for the Hom-1 Calicivirus on Human Cells. mBio 2017; 8:mBio.00031-17. [PMID: 28196955 PMCID: PMC5312078 DOI: 10.1128/mbio.00031-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Hom-1 vesivirus was reported in 1998 following the inadvertent transmission of the animal calicivirus San Miguel sea lion virus to a human host in a laboratory. We characterized the Hom-1 strain and investigated the mechanism by which human cells could be infected. An expression library of 3,559 human plasma membrane proteins was screened for reactivity with Hom-1 virus-like particles, and a single interacting protein, human junctional adhesion molecule 1 (hJAM1), was identified. Transient expression of hJAM1 conferred susceptibility to Hom-1 infection on nonpermissive Chinese hamster ovary (CHO) cells. Virus infection was markedly inhibited when CHO cells stably expressing hJAM were pretreated with anti-hJAM1 monoclonal antibodies. Cell lines of human origin were tested for growth of Hom-1, and efficient replication was observed in HepG2, HuH7, and SK-CO15 cells. The three cell lines (of hepatic or intestinal origin) were confirmed to express hJAM1 on their surface, and clustered regularly interspaced short palindromic repeats/Cas9-mediated knockout of the hJAM1 gene in each line abolished Hom-1 propagation. Taken together, our data indicate that entry of the Hom-1 vesivirus into these permissive human cell lines is mediated by the plasma membrane protein hJAM1 as a functional receptor.IMPORTANCE Vesiviruses, such as San Miguel sea lion virus and feline calicivirus, are typically associated with infection in animal hosts. Following the accidental infection of a laboratory worker with San Miguel sea lion virus, a related virus was isolated in cell culture and named Hom-1. In this study, we found that Hom-1 could be propagated in a number of human cell lines, making it the first calicivirus to replicate efficiently in cultured human cells. Screening of a library of human cell surface membrane proteins showed that the virus could utilize human junctional adhesion molecule 1 as a receptor to enter cells and initiate replication. The Hom-1 virus presents a new system for the study of calicivirus biology and species specificity.
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The Norovirus NS3 Protein Is a Dynamic Lipid- and Microtubule-Associated Protein Involved in Viral RNA Replication. J Virol 2017; 91:JVI.02138-16. [PMID: 27881660 DOI: 10.1128/jvi.02138-16] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 11/18/2016] [Indexed: 01/03/2023] Open
Abstract
Norovirus (NoV) infections are a significant health burden to society, yet the lack of reliable tissue culture systems has hampered the development of appropriate antiviral therapies. Here we show that the NoV NS3 protein, derived from murine NoV (MNV), is intimately associated with the MNV replication complex and the viral replication intermediate double-stranded RNA (dsRNA). We observed that when expressed individually, MNV NS3 and NS3 encoded by human Norwalk virus (NV) induced the formation of distinct vesicle-like structures that did not colocalize with any particular protein markers to cellular organelles but localized to cellular membranes, in particular those with a high cholesterol content. Both proteins also showed some degree of colocalization with the cytoskeleton marker β-tubulin. Although the distribution of MNV and NV NS3s were similar, NV NS3 displayed a higher level of colocalization with the Golgi apparatus and the endoplasmic reticulum (ER). However, we observed that although both proteins colocalized in membranes counterstained with filipin, an indicator of cholesterol content, MNV NS3 displayed a greater association with flotillin and stomatin, proteins known to associate with sphingolipid- and cholesterol-rich microdomains. Utilizing time-lapse epifluorescence microscopy, we observed that the membrane-derived vesicular structures induced by MNV NS3 were highly motile and dynamic in nature, and their movement was dependent on intact microtubules. These results begin to interrogate the functions of NoV proteins during virus replication and highlight the conserved properties of the NoV NS3 proteins among the seven Norovirus genogroups. IMPORTANCE Many mechanisms involved in the replication of norovirus still remain unclear, including the role for the NS3 protein, one of seven nonstructural viral proteins, which remains to be elucidated. This study reveals that murine norovirus (MNV) NS3 is intimately associated with the viral replication complex and dsRNA. We observed that the NS3 proteins of both MNV and Norwalk virus (NV) induce prominent vesicular structures and that this formation is dependent on microtubules and cellular cholesterol. Thus, this study contributes to our understanding of protein function within different Norovirus genogroups and expands a growing knowledge base on the interaction between positive-strand RNA [(+)RNA] viruses and cellular membranes that contribute to the biogenesis of virus-induced membrane organelles. This study contributes to our understanding of viral protein function and the ability of a viral protein to recruit specific cellular organelles and lipids that enable replication.
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Lateef Z, Gimenez G, Baker ES, Ward VK. Transcriptomic analysis of human norovirus NS1-2 protein highlights a multifunctional role in murine monocytes. BMC Genomics 2017; 18:39. [PMID: 28056773 PMCID: PMC5217272 DOI: 10.1186/s12864-016-3417-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 12/12/2016] [Indexed: 12/22/2022] Open
Abstract
Background The GII.4 Sydney 2012 strain of human norovirus (HuNoV) is a pandemic strain that is responsible for the majority of norovirus outbreaks in healthcare settings. The function of the non-structural (NS)1-2 protein from HuNoV is unknown. Results In silico analysis of human norovirus NS1-2 protein showed that it shares features with the murine NS1-2 protein, including a disordered region, a transmembrane domain and H-box and NC sequence motifs. The proteins also contain caspase cleavage and phosphorylation sites, indicating that processing and phosphorylation may be a conserved feature of norovirus NS1-2 proteins. In this study, RNA transcripts of human and murine norovirus full-length and the disordered region of NS1-2 were transfected into monocytes, and next generation sequencing was used to analyse the transcriptomic profile of cells expressing virus proteins. The profiles were then compared to the transcriptomic profile of MNV-infected cells. Conclusions RNAseq analysis showed that NS1-2 proteins from human and murine noroviruses affect multiple immune systems (chemokine, cytokine, and Toll-like receptor signaling) and intracellular pathways (NFκB, MAPK, PI3K-Akt signaling) in murine monocytes. Comparison to the transcriptomic profile of MNV-infected cells indicated the pathways that NS1-2 may affect during norovirus infection. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3417-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zabeen Lateef
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, 720 Cumberland St, Dunedin, 9054, New Zealand.
| | - Gregory Gimenez
- Otago Genomics and Bioinformatics Facility, University of Otago, Dunedin, 9054, New Zealand
| | - Estelle S Baker
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, 720 Cumberland St, Dunedin, 9054, New Zealand
| | - Vernon K Ward
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, 720 Cumberland St, Dunedin, 9054, New Zealand
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Structure(s), function(s), and inhibition of the RNA-dependent RNA polymerase of noroviruses. Virus Res 2016; 234:21-33. [PMID: 28041960 PMCID: PMC7114559 DOI: 10.1016/j.virusres.2016.12.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/19/2016] [Accepted: 12/24/2016] [Indexed: 12/17/2022]
Abstract
This review summarizes current knowledge on the norovirus RdRp. Multiple X-ray structures of norovirus RdRp show important conformational changes. Norovirus RdRp recognizes specific promotor sequences to initiate RNA synthesis. Anti-HCV nucleoside analogs such as 2CM-C also inhibit Norovirus RdRp. Suramin and its analogs act as allosteric non-nucleoside polymerase inhibitors.
Noroviruses belong to the Caliciviridae family of single-stranded positive-sense RNA viruses. The genus Norovirus includes seven genogroups (designated GI-GVII), of which GI, GII and GIV infect humans. Human noroviruses are responsible for widespread outbreaks of acute gastroenteritis and represent one of the most common causes of foodborne illness. No vaccine or antiviral treatment options are available for norovirus infection. The RNA-dependent RNA polymerase (RdRp) of noroviruses is a key enzyme responsible for transcription and replication of the viral genome. Here, we review the progress made in understanding the structures and functions of norovirus RdRp and its use as a target for small molecule inhibitors. Crystal structures of the RdRp at different stages of substrate interaction have been determined, which shed light on its multi-step catalytic cycle. The in vitro assays and in vivo animal models that have been developed to identify and characterize inhibitors of norovirus RdRp are also summarized, followed by an update on the current antiviral research targeting different regions of norovirus RdRp. In the future, structure-based drug design and rational optimization of known nucleoside and non-nucleoside inhibitors of norovirus RdRp may pave the way towards the next generation of direct-acting antivirals.
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26
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Qu L, Murakami K, Broughman JR, Lay MK, Guix S, Tenge VR, Atmar RL, Estes MK. Replication of Human Norovirus RNA in Mammalian Cells Reveals Lack of Interferon Response. J Virol 2016; 90:8906-23. [PMID: 27466422 PMCID: PMC5021416 DOI: 10.1128/jvi.01425-16] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 07/18/2016] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Human noroviruses (HuNoVs), named after the prototype strain Norwalk virus (NV), are a leading cause of acute gastroenteritis outbreaks worldwide. Studies on the related murine norovirus (MNV) have demonstrated the importance of an interferon (IFN) response in host control of virus replication, but this remains unclear for HuNoVs. Despite the lack of an efficient cell culture infection system, transfection of stool-isolated NV RNA into mammalian cells leads to viral RNA replication and virus production. Using this system, we show here that NV RNA replication is sensitive to type I (α/β) and III (interleukin-29 [IL-29]) IFN treatment. However, in cells capable of a strong IFN response to Sendai virus (SeV) and poly(I·C), NV RNA replicates efficiently and generates double-stranded RNA without inducing a detectable IFN response. Replication of HuNoV genogroup GII.3 strain U201 RNA, generated from a reverse genetics system, also does not induce an IFN response. Consistent with a lack of IFN induction, NV RNA replication is enhanced neither by neutralization of type I/III IFNs through neutralizing antibodies or the soluble IFN decoy receptor B18R nor by short hairpin RNA (shRNA) knockdown of mitochondrial antiviral signaling protein (MAVS) or interferon regulatory factor 3 (IRF3) in the IFN induction pathways. In contrast to other positive-strand RNA viruses that block IFN induction by targeting MAVS for degradation, MAVS is not degraded in NV RNA-replicating cells, and an SeV-induced IFN response is not blocked. Together, these results indicate that HuNoV RNA replication in mammalian cells does not induce an IFN response, suggesting that the epithelial IFN response may play a limited role in host restriction of HuNoV replication. IMPORTANCE Human noroviruses (HuNoVs) are a leading cause of epidemic gastroenteritis worldwide. Due to lack of an efficient cell culture system and robust small-animal model, little is known about the innate host defense to these viruses. Studies on murine norovirus (MNV) have shown the importance of an interferon (IFN) response in host control of MNV replication, but this remains unclear for HuNoVs. Here, we investigated the IFN response to HuNoV RNA replication in mammalian cells using Norwalk virus stool RNA transfection, a reverse genetics system, IFN neutralization reagents, and shRNA knockdown methods. Our results show that HuNoV RNA replication in mammalian epithelial cells does not induce an IFN response, nor can it be enhanced by blocking the IFN response. These results suggest a limited role of the epithelial IFN response in host control of HuNoV RNA replication, providing important insights into our understanding of the host defense to HuNoVs that differs from that to MNV.
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Affiliation(s)
- Lin Qu
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Kosuke Murakami
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - James R Broughman
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Margarita K Lay
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Susana Guix
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Victoria R Tenge
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Robert L Atmar
- Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
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27
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Karst SM, Tibbetts SA. Recent advances in understanding norovirus pathogenesis. J Med Virol 2016; 88:1837-43. [PMID: 27110852 DOI: 10.1002/jmv.24559] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2016] [Indexed: 01/17/2023]
Abstract
Noroviruses constitute a family of ubiquitous and highly efficient human pathogens. In spite of decades of dedicated research, human noroviruses remain a major cause of gastroenteritis and severe diarrheal disease around the world. Recent findings have begun to unravel the complex mechanisms that regulate norovirus pathogenesis and persistent infection, including the important interplay between the virus, the host immune system, and commensal bacteria. Herein, we will summarize recent research developments regarding norovirus cell tropism, the use of M cells, and commensal bacteria to facilitate norovirus infection, and virus, host, and bacterial determinants of persistent norovirus infections. J. Med. Virol. 88:1837-1843, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Stephanie M Karst
- Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute, University of Florida, Gainesville, Florida
| | - Scott A Tibbetts
- Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute, University of Florida, Gainesville, Florida
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28
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29
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Roth AN, Karst SM. Norovirus mechanisms of immune antagonism. Curr Opin Virol 2015; 16:24-30. [PMID: 26673810 DOI: 10.1016/j.coviro.2015.11.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/03/2015] [Accepted: 11/11/2015] [Indexed: 01/01/2023]
Abstract
Noroviruses are a leading cause of gastroenteritis outbreaks globally. Several lines of evidence indicate that noroviruses can antagonize or evade host immune responses, including the absence of long-lasting immunity elicited during a primary norovirus exposure and the ability of noroviruses to establish prolonged infections that are associated with protracted viral shedding. Specific norovirus proteins possessing immune antagonist activity have been described in recent years although mechanistic insight in most cases is limited. In this review, we discuss these emerging strategies used by noroviruses to subvert the immune response, including the actions of two nonstructural proteins (p48 and p22) to impair cellular protein trafficking and secretory pathways; the ability of the VF1 protein to inhibit cytokine induction; and the ability of the minor structural protein VP2 to regulate antigen presentation. We also discuss the current state of the understanding of host and viral factors regulating the establishment of persistent norovirus infections along the gastrointestinal tract. A more detailed understanding of immune antagonism by pathogenic viruses will inform prevention and treatment of disease.
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Affiliation(s)
- Alexa N Roth
- College of Medicine, Department of Molecular Genetics & Microbiology, Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
| | - Stephanie M Karst
- College of Medicine, Department of Molecular Genetics & Microbiology, Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States.
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30
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Urakova N, Frese M, Hall RN, Liu J, Matthaei M, Strive T. Expression and partial characterisation of rabbit haemorrhagic disease virus non-structural proteins. Virology 2015; 484:69-79. [DOI: 10.1016/j.virol.2015.05.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 05/08/2015] [Indexed: 02/06/2023]
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31
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Kocher J, Yuan L. Norovirus vaccines and potential antinorovirus drugs: recent advances and future perspectives. Future Virol 2015; 10:899-913. [PMID: 26568768 DOI: 10.2217/fvl.15.57] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Human noroviruses (HuNoVs) are a leading cause of acute, nonbacterial gastroenteritis worldwide. The lack of a cell culture system and smaller animal model has delayed the development and commercial availability of vaccines and antiviral drugs. Current vaccines rely on recombinant capsid proteins, such as P particles and virus-like particles (VLPs), which have been promising in clinical trials. Anti-HuNoV drug development is another area of extensive research, including currently available antiviral drugs for other viral pathogens. This review will provide an overview of recent advances in vaccine and antiviral development. The implication of recent advances in HuNoV cell culture for improving vaccine and antiviral development is also discussed.
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Affiliation(s)
- Jacob Kocher
- Department of Biomedical Sciences & Pathobiology, Center for Molecular Medicine & Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061-0913, USA
| | - Lijuan Yuan
- Department of Biomedical Sciences & Pathobiology, Center for Molecular Medicine & Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061-0913, USA
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32
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Kim SH, Chen S, Jiang X, Green KY, Samal SK. Immunogenicity of Newcastle disease virus vectors expressing Norwalk virus capsid protein in the presence or absence of VP2 protein. Virology 2015; 484:163-169. [PMID: 26099695 DOI: 10.1016/j.virol.2015.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 05/29/2015] [Accepted: 06/02/2015] [Indexed: 11/16/2022]
Abstract
Noroviruses are the most common cause of acute gastroenteritis in humans. Development of an effective vaccine is required for reducing their outbreaks. In order to develop a GI norovirus vaccine, Newcastle disease virus vectors, rLaSota and modified rBC, were used to express VP1 protein of Norwalk virus. Co-expression of VP1 and VP2 proteins by Newcastle disease virus vectors resulted in enhanced expression of Norwalk virus VP1 protein and self-assembly of VP1 protein into virus-like particles. Furthermore, the Norwalk virus-specific IgG response induced in mice by Newcastle disease virus vectors was similar to that induced by baculovirus-expressed virus-like particles in mice. However, the modified rBC vector in the presence of VP2 protein induced significantly higher levels of cellular and mucosal immune responses than those induced by baculovirus-expressed VLPs. These results indicate that Newcastle disease virus has great potential for developing a live Norwalk virus vaccine by inducing humoral, cellular and mucosal immune responses in humans.
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Affiliation(s)
- Shin-Hee Kim
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Shun Chen
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Xi Jiang
- Division of Infectious Disease, Cincinnati Children׳s Hospital Medical Center, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Kim Y Green
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institute of Health, DHHS, Bethesda, MD, USA
| | - Siba K Samal
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, USA.
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33
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Murine norovirus replication induces G0/G1 cell cycle arrest in asynchronously growing cells. J Virol 2015; 89:6057-66. [PMID: 25810556 DOI: 10.1128/jvi.03673-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/20/2015] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED Many viruses replicate most efficiently in specific phases of the cell cycle, establishing or exploiting favorable conditions for viral replication, although little is known about the relationship between caliciviruses and the cell cycle. Microarray and Western blot analysis of murine norovirus 1 (MNV-1)-infected cells showed changes in cyclin transcript and protein levels indicative of a G1 phase arrest. Cell cycle analysis confirmed that MNV-1 infection caused a prolonging of the G1 phase and an accumulation of cells in the G0/G1 phase. The accumulation in G0/G1 phase was caused by a reduction in cell cycle progression through the G1/S restriction point, with MNV-1-infected cells released from a G1 arrest showing reduced cell cycle progression compared to mock-infected cells. MNV-1 replication was compared in populations of cells synchronized into specific cell cycle phases and in asynchronously growing cells. Cells actively progressing through the G1 phase had a 2-fold or higher increase in virus progeny and capsid protein expression over cells in other phases of the cell cycle or in unsynchronized populations. These findings suggest that MNV-1 infection leads to prolonging of the G1 phase and a reduction in S phase entry in host cells, establishing favorable conditions for viral protein production and viral replication. There is limited information on the interactions between noroviruses and the cell cycle, and this observation of increased replication in the G1 phase may be representative of other members of the Caliciviridae. IMPORTANCE Noroviruses have proven recalcitrant to growth in cell culture, limiting our understanding of the interaction between these viruses and the infected cell. In this study, we used the cell-culturable MNV-1 to show that infection of murine macrophages affects the G1/S cell cycle phase transition, leading to an arrest in cell cycle progression and an accumulation of cells in the G0/G1 phase. Furthermore, we show that MNV replication is enhanced in the G1 phase compared to other stages of the cell cycle. Manipulating the cell cycle or adapting to cell cycle responses of the host cell is a mechanism to enhance virus replication. To the best of our knowledge, this is the first report of a norovirus interacting with the host cell cycle and exploiting the favorable conditions of the G0/G1 phase for RNA virus replication.
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Rocha-Pereira J, Neyts J, Jochmans D. Norovirus: targets and tools in antiviral drug discovery. Biochem Pharmacol 2014; 91:1-11. [PMID: 24893351 PMCID: PMC7111065 DOI: 10.1016/j.bcp.2014.05.021] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 05/23/2014] [Accepted: 05/27/2014] [Indexed: 11/29/2022]
Abstract
The development of antiviral strategies to treat or prevent norovirus infections is a pressing matter. Noroviruses are the number 1 cause of acute gastroenteritis, of foodborne illness, of sporadic gastroenteritis in all age groups and of severe acute gastroenteritis in children less than 5 years old seeking medical assistance [USA/CDC]. In developing countries, noroviruses are linked to significant mortality (~200,000 children <5 years old). Noroviruses are a major culprit for the closure of hospital wards, and associated with increased hospitalization and mortality among the elderly. Transplant patients have significant risk of acquiring persistent norovirus gastroenteritis. Control and prevention strategies are limited to the use of disinfectants and hand sanitizers, whose efficacy is frequently insufficient. Hence, there is an ample need for antiviral treatment and prophylaxis of norovirus infections. The fact that only a handful of inhibitors of norovirus replication have been reported can largely be attributable to the hampering inability to cultivate human noroviruses in cell culture. The Norwalk replicon-bearing cells and the murine norovirus-infected cell lines are the available models to assess in vitro antiviral activity of compounds. Human noroviruses have been shown to replicate (to some extent) in mice, calves, gnotobiotic pigs, and chimpanzees. Infection of interferon-deficient mice with the murine norovirus results in virus-induced diarrhea. Here we review recent developments in understanding which norovirus proteins or host cell factors may serve as targets for inhibition of viral replication. Given the recent advances, significant progress in the search for antiviral strategies against norovirus infections is expected in the upcoming years.
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Affiliation(s)
- Joana Rocha-Pereira
- Rega Institute for Medical Research, KU Leuven - University of Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Johan Neyts
- Rega Institute for Medical Research, KU Leuven - University of Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium.
| | - Dirk Jochmans
- Rega Institute for Medical Research, KU Leuven - University of Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
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Borin BN, Tang W, Nice TJ, McCune BT, Virgin HW, Krezel AM. Murine norovirus protein NS1/2 aspartate to glutamate mutation, sufficient for persistence, reorients side chain of surface exposed tryptophan within a novel structured domain. Proteins 2013; 82:1200-9. [PMID: 24273131 DOI: 10.1002/prot.24484] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 11/12/2013] [Accepted: 11/20/2013] [Indexed: 11/06/2022]
Abstract
Compact viral genomes such as those found in noroviruses, which cause significant enteric disease in humans, often encode only a few proteins, but affect a wide range of processes in their hosts and ensure efficient propagation of the virus. Both human and mouse noroviruses (MNVs) persistently replicate and are shed in stool, a highly effective strategy for spreading between hosts. For MNV, the presence of a glutamate rather than an aspartate at position 94 of the NS1/2 protein was previously shown to be essential for persistent replication and shedding. Here, we analyze these critical sequences of NS1/2 at the structural level. Using solution nuclear magnetic resonance methods, we determined folded NS1/2 domain structures from a nonpersistent murine norovirus strain CW3, a persistent strain CR6, and a persistent mutant strain CW3(D94E). We found an unstructured PEST-like domain followed by a novel folded domain in the N-terminus of NS1/2. All three forms of the domain are stable and monomeric in solution. Residue 94, critical for determining persistence, is located in a reverse turn following an α-helix in the folded domain. The longer side chain of glutamate, but not aspartate, allows interaction with the indole group of the nearby tryptophan, reshaping the surface of the domain. The discrimination between glutamyl and aspartyl residue is imposed by the stable tertiary conformation. These structural requirements correlate with the in vivo function of NS1/2 in persistence, a key element of norovirus biology and infection.
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Abstract
Noroviruses are small, positive-sense RNA viruses within the family Caliciviridae, and are now accepted widely as a major cause of acute gastroenteritis in both developed and developing countries. Despite their impact, our understanding of the life cycle of noroviruses has lagged behind that of other RNA viruses due to the inability to culture human noroviruses (HuNVs). Our knowledge of norovirus biology has improved significantly over the past decade as a result of numerous technological advances. The use of a HuNV replicon, improved biochemical and cell-based assays, combined with the discovery of a murine norovirus capable of replication in cell culture, has improved greatly our understanding of the molecular mechanisms of norovirus genome translation and replication, as well as the interaction with host cell processes. In this review, the current state of knowledge of the intracellular life of noroviruses is discussed with particular emphasis on the mechanisms of viral gene expression and viral genome replication.
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Affiliation(s)
- Lucy G Thorne
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Ian G Goodfellow
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
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Tsai CN, Lin CY, Lin CW, Shih KC, Chiu CH, Chen SY. Clinical relevance and genotypes of circulating noroviruses in northern Taiwan, 2006-2011. J Med Virol 2013; 86:335-46. [DOI: 10.1002/jmv.23728] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/08/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Chi-Neu Tsai
- Graduate Institute of Clinical Medical Sciences; Chang Gung University; Kweishan Taoyuan Taiwan
| | - Chun-Yuan Lin
- Department of Computer Science and Information Engineering; Chang Gung University; Kweishan Taoyuan Taiwan
| | - Che-Wei Lin
- Graduate Institute of Clinical Medical Sciences; Chang Gung University; Kweishan Taoyuan Taiwan
| | - Kuei-Chung Shih
- Department of Computer Science; National Tsing Hua University; Hsinchu Taiwan
| | - Cheng-Hsun Chiu
- Division of Pediatric Infectious Diseases; Chang Gung Children's Hospital, Kweishan; Taoyuan Taiwan
- Molecular Infectious Disease Research Center; Chang Gung Memorial Hospital, Kweishan; Taoyuan Taiwan
| | - Shih-Yen Chen
- Division of Pediatric Gastroenterology; Chang Gung Children's Hospital; Kweishan Taoyuan Taiwan
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Development of Norwalk virus-specific monoclonal antibodies with therapeutic potential for the treatment of Norwalk virus gastroenteritis. J Virol 2013; 87:9547-57. [PMID: 23785216 DOI: 10.1128/jvi.01376-13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Passive immunoprophylaxis or immunotherapy with norovirus-neutralizing monoclonal antibodies (MAbs) could be a useful treatment for high-risk populations, including infants and young children, the elderly, and certain patients who are debilitated or immunocompromised. In order to obtain antinorovirus MAbs with therapeutic potential, we stimulated a strong adaptive immune response in chimpanzees to the prototype norovirus strain Norwalk virus (NV) (genogroup I.1). A combinatorial phage Fab display library derived from mRNA of the chimpanzees' bone marrow was prepared, and four distinct Fabs reactive with Norwalk recombinant virus-like particles (rVLPs) were recovered, with estimated binding affinities in the subnanomolar range. Mapping studies showed that the four Fabs recognized three different conformational epitopes in the protruding (P) domain of NV VP1, the major capsid protein. The epitope of one of the Fabs, G4, was further mapped to a specific site involving a key amino acid residue, Gly365. One additional specific Fab (F11) was recovered months later from immortalized memory B cells and partially characterized. The anti-NV Fabs were converted into full-length IgG (MAbs) with human γ1 heavy chain constant regions. The anti-NV MAbs were tested in the two available surrogate assays for Norwalk virus neutralization, which showed that the MAbs could block carbohydrate binding and inhibit hemagglutination by NV rVLP. By mixing a single MAb with live Norwalk virus prior to challenge, MAbs D8 and B7 neutralized the virus and prevented infection in a chimpanzee. Because chimpanzee immunoglobulins are virtually identical to human immunoglobulins, these chimpanzee anticapsid MAbs may have a clinical application.
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A single-amino-acid change in murine norovirus NS1/2 is sufficient for colonic tropism and persistence. J Virol 2012; 87:327-34. [PMID: 23077309 DOI: 10.1128/jvi.01864-12] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human norovirus (HuNoV) is the major cause of acute nonbacterial gastroenteritis worldwide but has no clear animal reservoir. HuNoV can persist after the resolution of symptoms, and this persistence may be essential for viral maintenance within the population. Many strains of the related murine norovirus (MNV) also persist, providing a tractable animal model for studying norovirus (NoV) persistence. We have used recombinant cDNA clones of representative persistent (CR6) and nonpersistent (CW3) strains to identify a domain within the nonstructural gene NS1/2 that is necessary and sufficient for persistence. Furthermore, we found that a single change of aspartic acid to glutamic acid in CW3 NS1/2 was sufficient for persistence. This same conservative change also caused increased growth of CW3 in the proximal colon, which we found to be a major tissue reservoir of MNV persistence, suggesting that NS1/2 determines viral tropism that is necessary for persistence. These findings represent the first identified function for NoV NS1/2 during infection and establish a novel model system for the study of enteric viral persistence.
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Abstract
Human noroviruses (HuNoV) are a major cause of nonbacterial gastroenteritis worldwide, yet details of the life cycle and replication of HuNoV are relatively unknown due to the lack of an efficient cell culture system. Studies with murine norovirus (MNV), which can be propagated in permissive cells, have begun to probe different aspects of the norovirus life cycle; however, our understanding of the specific functions of the viral proteins lags far behind that of other RNA viruses. Genome-wide functional profiling by insertional mutagenesis can reveal protein domains essential for replication and can lead to generation of tagged viruses, which has not yet been achieved for noroviruses. Here, transposon-mediated insertional mutagenesis was used to create 5 libraries of mutagenized MNV infectious clones, each containing a 15-nucleotide sequence randomly inserted within a defined region of the genome. Infectious virus was recovered from each library and was subsequently passaged in cell culture to determine the effect of each insertion by insertion-specific fluorescent PCR profiling. Genome-wide profiling of over 2,000 insertions revealed essential protein domains and confirmed known functional motifs. As validation, several insertion sites were introduced into a wild-type clone, successfully allowing the recovery of infectious virus. Screening of a number of reporter proteins and epitope tags led to the generation of the first infectious epitope-tagged noroviruses carrying the FLAG epitope tag in either NS4 or VP2. Subsequent work confirmed that epitope-tagged fully infectious noroviruses may be of use in the dissection of the molecular interactions that occur within the viral replication complex.
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Multiple antigenic sites are involved in blocking the interaction of GII.4 norovirus capsid with ABH histo-blood group antigens. J Virol 2012; 86:7414-26. [PMID: 22532688 DOI: 10.1128/jvi.06729-11] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Noroviruses are major etiological agents of acute viral gastroenteritis. In 2002, a GII.4 variant (Farmington Hills cluster) spread so rapidly in the human population that it predominated worldwide and displaced previous GII.4 strains. We developed and characterized a panel of six monoclonal antibodies (MAbs) directed against the capsid protein of a Farmington Hills-like GII.4 norovirus strain that was associated with a large hospital outbreak in Maryland in 2004. The six MAbs reacted with high titers against homologous virus-like particles (VLPs) by enzyme-linked immunoassay but did not react with denatured capsid protein in immunoblots. The expression and self-assembly of newly developed genogroup I/II chimeric VLPs showed that five MAbs bound to the GII.4 protruding (P) domain of the capsid protein, while one recognized the GII.4 shell (S) domain. Cross-competition assays and mutational analyses showed evidence for at least three distinct antigenic sites in the P domain and one in the S domain. MAbs that mapped to the P domain but not the S domain were able to block the interaction of VLPs with ABH histo-blood group antigens (HBGA), suggesting that multiple antigenic sites of the P domain are involved in HBGA blocking. Further analysis showed that two MAbs mapped to regions of the capsid that had been associated with the emergence of new GII.4 variants. Taken together, our data map antibody and HBGA carbohydrate binding to proximal regions of the norovirus capsid, showing that evolutionary pressures on the norovirus capsid protein may affect both antigenic and carbohydrate recognition phenotypes.
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Baker ES, Luckner SR, Krause KL, Lambden PR, Clarke IN, Ward VK. Inherent structural disorder and dimerisation of murine norovirus NS1-2 protein. PLoS One 2012; 7:e30534. [PMID: 22347381 PMCID: PMC3274520 DOI: 10.1371/journal.pone.0030534] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 12/23/2011] [Indexed: 11/28/2022] Open
Abstract
Human noroviruses are highly infectious viruses that cause the majority of acute, non-bacterial epidemic gastroenteritis cases worldwide. The first open reading frame of the norovirus RNA genome encodes for a polyprotein that is cleaved by the viral protease into six non-structural proteins. The first non-structural protein, NS1-2, lacks any significant sequence similarity to other viral or cellular proteins and limited information is available about the function and biophysical characteristics of this protein. Bioinformatic analyses identified an inherently disordered region (residues 1–142) in the highly divergent N-terminal region of the norovirus NS1-2 protein. Expression and purification of the NS1-2 protein of Murine norovirus confirmed these predictions by identifying several features typical of an inherently disordered protein. These were a biased amino acid composition with enrichment in the disorder promoting residues serine and proline, a lack of predicted secondary structure, a hydrophilic nature, an aberrant electrophoretic migration, an increased Stokes radius similar to that predicted for a protein from the pre-molten globule family, a high sensitivity to thermolysin proteolysis and a circular dichroism spectrum typical of an inherently disordered protein. The purification of the NS1-2 protein also identified the presence of an NS1-2 dimer in Escherichia coli and transfected HEK293T cells. Inherent disorder provides significant advantages including structural flexibility and the ability to bind to numerous targets allowing a single protein to have multiple functions. These advantages combined with the potential functional advantages of multimerisation suggest a multi-functional role for the NS1-2 protein.
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Affiliation(s)
- Estelle S. Baker
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Sylvia R. Luckner
- Department of Biochemistry, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Kurt L. Krause
- Department of Biochemistry, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Paul R. Lambden
- Molecular Microbiology and Infection, School of Medicine, University of Southampton, Southampton, United Kingdom
| | - Ian N. Clarke
- Molecular Microbiology and Infection, School of Medicine, University of Southampton, Southampton, United Kingdom
| | - Vernon K. Ward
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- * E-mail:
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43
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Liu P, Hsiao HM, Jaykus LA, Moe C. Quantification of Norwalk virus inocula: Comparison of endpoint titration and real-time reverse transcription-PCR methods. J Med Virol 2010; 82:1612-6. [PMID: 20648618 DOI: 10.1002/jmv.21851] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Human noroviruses (NoV) are the leading cause of epidemic acute gastroenteritis. In order to fully characterize features such as persistence and infectious dose, precise quantification of virus concentration is necessary. The purpose of this study was to compare two methods [endpoint titration RT-PCR and quantitative RT-PCR (RT-qPCR)] with respect to quantification of Norwalk virus (NV) in inocula made from purified stock suspensions of human fecal specimens. A full-length NV RNA transcript was developed to facilitate quantification using RT-qPCR and provided log linear detection in the range of 49-4.9 x 10(4) genome equivalent copies (GEC) per reaction. Endpoint titration RT-PCR was used to estimate PCR detection units, and RT-qPCR was used to estimate genome copies in two NV inocula (8fIIa and 8fIIb) used in previous human challenge studies. Overall, RT-qPCR was 1.1-1.6 log(10) more sensitive (lower detection limit) than endpoint titration RT-PCR when the same RNA release method, PCR primers and thermocycle program were used. These findings have important implications for many experimental interpretations, not the least of which is estimating the median infectious dose in human challenge studies.
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Affiliation(s)
- Pengbo Liu
- First Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
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44
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Sharp TM, Guix S, Katayama K, Crawford SE, Estes MK. Inhibition of cellular protein secretion by norwalk virus nonstructural protein p22 requires a mimic of an endoplasmic reticulum export signal. PLoS One 2010; 5:e13130. [PMID: 20976190 PMCID: PMC2956632 DOI: 10.1371/journal.pone.0013130] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 09/02/2010] [Indexed: 12/22/2022] Open
Abstract
Protein trafficking between the endoplasmic reticulum (ER) and Golgi apparatus is central to cellular homeostasis. ER export signals are utilized by a subset of proteins to rapidly exit the ER by direct uptake into COPII vesicles for transport to the Golgi. Norwalk virus nonstructural protein p22 contains a YXΦESDG motif that mimics a di-acidic ER export signal in both sequence and function. However, unlike normal ER export signals, the ER export signal mimic of p22 is necessary for apparent inhibition of normal COPII vesicle trafficking, which leads to Golgi disassembly and antagonism of Golgi-dependent cellular protein secretion. This is the first reported function for p22. Disassembly of the Golgi apparatus was also observed in cells replicating Norwalk virus, which may contribute to pathogenesis by interfering with cellular processes that are dependent on an intact secretory pathway. These results indicate that the ER export signal mimic is critical to the antagonistic function of p22, shown herein to be a novel antagonist of ER/Golgi trafficking. This unique and well-conserved human norovirus motif is therefore an appealing target for antiviral drug development.
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Affiliation(s)
- Tyler M. Sharp
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Susana Guix
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kazuhiko Katayama
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Sue E. Crawford
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mary K. Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
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45
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Abstract
PURPOSE OF REVIEW The cellular secretory pathway, composed of the endoplasmic reticulum, Golgi apparatus, and cellular vesicles, mediates the intracellular trafficking of proteins and lipids. Gastrointestinal pathogens frequently affect the functions of enterocytes, the differentiated cells involved in secretion and absorption of extracellular molecules. Microbial pathogenesis can be enhanced by altering the trafficking of key molecules such as brush border enzymes, soluble immune mediators such as cytokines and chemokines, and MHC Class I molecules, all of which rely on the secretory pathway for their appropriate cellular localization. This review focuses on our current understanding of the distinct mechanisms employed by enteric pathogens to antagonize the secretory pathway. RECENT FINDINGS Many pathogens encode individual or multiple proteins to antagonize the secretory pathway, including disrupting the trafficking of vesicles between the endoplasmic reticulum, Golgi, and plasma membrane. This antagonism allows for increased pathogenesis and can assist, directly or indirectly, in microbial replication. Virtually all arms of the secretory pathway are targeted by intestinal pathogens, supporting the pathogenic significance of shutting this pathway down. SUMMARY This review summarizes the mechanisms utilized by gut pathogens to disrupt the cellular secretory pathway and addresses potential therapeutic targets to combat these highly prevalent and burdensome microbes.
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Affiliation(s)
- Tyler M Sharp
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
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46
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Hyde JL, Mackenzie JM. Subcellular localization of the MNV-1 ORF1 proteins and their potential roles in the formation of the MNV-1 replication complex. Virology 2010; 406:138-48. [PMID: 20674956 DOI: 10.1016/j.virol.2010.06.047] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 06/22/2010] [Accepted: 06/30/2010] [Indexed: 11/15/2022]
Abstract
Human noroviruses are the leading cause of nonbacterial gastroenteritis worldwide and are now recognised as a significant human pathogen. Whereas human noroviruses cannot be cultivated in the laboratory, mouse norovirus 1 (MNV-1) is easily cultivated and has a defined tropism for cells of a mononuclear origin. As such, MNV-1 provides an ideal opportunity to study many aspects of norovirus biology and replication. Previously, we have shown that MNV-1 RNA replication is associated with components of the early and late secretory pathway and that all six open reading frame 1 (ORF1) proteins are associated with the viral dsRNA within the replication complex (RC) during the course of infection. In this study, we further characterise the subcellular localisation of the MNV-1 ORF1 proteins when recombinantly expressed in cells. We show that two MNV-1 proteins, NS1-2 and NS4, associate with the endoplasmic reticulum and endosomes, respectively. Whereas NS6 (the viral protease) appeared to localize within the cytoplasm and to mitochondria, NS7 (the viral polymerase) was observed to localize diffusely within the cytoplasm and within the nucleus, and NS3 localized to discrete foci within the cytoplasm which were of unknown origin. Based on the localization patterns observed we propose a model by which NS1-2 and NS4 may recruit host membranes to the MNV-1 RC during replication.
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Affiliation(s)
- Jennifer L Hyde
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia
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47
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Karst SM. Pathogenesis of noroviruses, emerging RNA viruses. Viruses 2010; 2:748-781. [PMID: 21994656 PMCID: PMC3185648 DOI: 10.3390/v2030748] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 03/15/2010] [Accepted: 03/15/2010] [Indexed: 12/13/2022] Open
Abstract
Human noroviruses in the family Caliciviridae are a major cause of epidemic gastroenteritis. They are responsible for at least 95% of viral outbreaks and over 50% of all outbreaks worldwide. Transmission of these highly infectious plus-stranded RNA viruses occurs primarily through contaminated food or water, but also through person-to-person contact and exposure to fomites. Norovirus infections are typically acute and self-limited. However, disease can be much more severe and prolonged in infants, elderly, and immunocompromised individuals. Norovirus outbreaks frequently occur in semi-closed communities such as nursing homes, military settings, schools, hospitals, cruise ships, and disaster relief situations. Noroviruses are classified as Category B biodefense agents because they are highly contagious, extremely stable in the environment, resistant to common disinfectants, and associated with debilitating illness. The number of reported norovirus outbreaks has risen sharply since 2002 suggesting the emergence of more infectious strains. There has also been increased recognition that noroviruses are important causes of childhood hospitalization. Moreover, noroviruses have recently been associated with multiple clinical outcomes other than gastroenteritis. It is unclear whether these new observations are due to improved norovirus diagnostics or to the emergence of more virulent norovirus strains. Regardless, it is clear that human noroviruses cause considerable morbidity worldwide, have significant economic impact, and are clinically important emerging pathogens. Despite the impact of human norovirus-induced disease and the potential for emergence of highly virulent strains, the pathogenic features of infection are not well understood due to the lack of a cell culture system and previous lack of animal models. This review summarizes the current understanding of norovirus pathogenesis from the histological to the molecular level, including contributions from new model systems.
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Affiliation(s)
- Stephanie M. Karst
- Center for Molecular and Tumor Virology, Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932, USA; E-Mail: ; Tel.: +1-318-675-8122; Fax: +1-318-675-5764
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Bailey D, Kaiser WJ, Hollinshead M, Moffat K, Chaudhry Y, Wileman T, Sosnovtsev SV, Goodfellow IG. Feline calicivirus p32, p39 and p30 proteins localize to the endoplasmic reticulum to initiate replication complex formation. J Gen Virol 2009; 91:739-49. [PMID: 19906938 PMCID: PMC2885758 DOI: 10.1099/vir.0.016279-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In common with other positive-strand RNA viruses, replication of feline calicivirus (FCV) results in rearrangement of intracellular membranes and production of numerous membrane-bound vesicular structures on which viral genome replication is thought to occur. In this study, bioinformatics approaches have identified three of the FCV non-structural proteins, namely p32, p39 and p30, as potential transmembrane proteins. These proteins were able to target enhanced cyan fluorescent protein to membrane fractions where they behaved as integral membrane proteins. Immunofluorescence microscopy of these proteins expressed in cells showed co-localization with endoplasmic reticulum (ER) markers. Further electron microscopy analysis of cells co-expressing FCV p39 or p30 with a horseradish peroxidase protein containing the KDEL ER retention motif demonstrated gross morphological changes to the ER. Similar reorganization patterns, especially for those produced by p30, were observed in naturally infected Crandel–Rees feline kidney cells. Together, the data demonstrate that the p32, p39 and p30 proteins of FCV locate to the ER and lead to reorganization of ER membranes. This suggests that they may play a role in the generation of FCV replication complexes and that the endoplasmic reticulum may represent the potential source of the membrane vesicles induced during FCV infection.
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Affiliation(s)
- Dalan Bailey
- Department of Virology, Imperial College London, London W2 1PG, UK.
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49
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Kamel AH, Ali MA, El-Nady HG, Aho S, Pothier P, Belliot G. Evidence of the co-circulation of enteric viruses in sewage and in the population of Greater Cairo. J Appl Microbiol 2009; 108:1620-9. [PMID: 19840175 DOI: 10.1111/j.1365-2672.2009.04562.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS To characterize major enteric viruses (enterovirus, rotavirus, norovirus, astrovirus and adenovirus) in the sewage of Greater Cairo and to compare the results with clinical data collected during the same period. METHODS AND RESULTS Seventy-two sewage samples from two waste water treatment plants were collected from April 2006 through February 2007. Enteroviruses, noroviruses (NoVs) and rotaviruses (RVs) were detected by RT-PCR in 22%, 18% and 8.3% of the samples, respectively. No adenovirus and astrovirus was detected. G2P[8], G9P[8], G1P[8], G2P[4] and rare G12 RV isolates were detected in the environment as well as a bovine RV. The environmental NoV strains mostly belonged to genogroup I (84%). Rotaviruses and some of the NoVs were similar to those found in the clinical samples at the same time. CONCLUSIONS The comparison of environmental and clinical data suggests that similar RV and NoV isolates were circulating in the environment and in the population during the same period. SIGNIFICANCE AND IMPACT OF THE STUDY Few studies have investigated the prevalence and the epidemiology of RVs and NoVs in Cairo. This work is the first to establish a correlation between viral gastroenteritis and the concomitant presence of enteric viruses in the environment for Greater Cairo where combined environmental and clinical surveys should help to prevent infections caused by these major pathogens.
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Affiliation(s)
- A H Kamel
- Laboratory of Virology, National Reference Center for Enteric Viruses, Public Hospital of Dijon, Dijon, France
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50
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Abstract
Noroviruses are a major cause of epidemic gastroenteritis in children and adults, and GII.4 has been the predominant genotype since its first documented occurrence in 1987. This study examined the evolutionary dynamics of GII.4 noroviruses over more than three decades to investigate possible mechanisms by which these viruses have emerged to become predominant. Stool samples (n = 5,424) from children hospitalized at the Children's Hospital in Washington, DC, between 1974 and 1991 were screened for the presence of noroviruses by a custom multiplex real-time reverse transcription-PCR. The complete genome sequences of five GII.4 noroviruses (three of which predate 1987 by more than a decade) in this archival collection were determined and compared to the sequences of contemporary strains. Evolutionary analysis determined that the GII.4 VP1 capsid gene evolved at a rate of 4.3 x 10(-3) nucleotide substitutions/site/year. Only six sites in the VP1 capsid protein were found to evolve under positive selection, most of them located in the shell domain. No unique mutations were observed in or around the two histoblood group antigen (HBGA) binding sites in the P region, indicating that this site has been conserved since the 1970s. The VP1 proteins from the 1974 to 1977 noroviruses contained a unique sequence of four consecutive amino acids in the P2 region, which formed an exposed protrusion on the modeled capsid structure. This protrusion and other observed sequence variations did not affect the HBGA binding profiles of recombinant virus-like particles derived from representative 1974 and 1977 noroviruses compared with more recent noroviruses. Our analysis of archival GII.4 norovirus strains suggests that this genotype has been circulating for more than three decades and provides new ancestral strain sequences for the analysis of GII.4 evolution.
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