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De Gaetano GV, Lentini G, Coppolino F, Famà A, Pietrocola G, Beninati C. Engagement of α 3β 1 and α 2β 1 integrins by hypervirulent Streptococcus agalactiae in invasion of polarized enterocytes. Front Microbiol 2024; 15:1367898. [PMID: 38511003 PMCID: PMC10951081 DOI: 10.3389/fmicb.2024.1367898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 02/19/2024] [Indexed: 03/22/2024] Open
Abstract
The gut represents an important site of colonization of the commensal bacterium Streptococcus agalactiae (group B Streptococcus or GBS), which can also behave as a deadly pathogen in neonates and adults. Invasion of the intestinal epithelial barrier is likely a crucial step in the pathogenesis of neonatal infections caused by GBS belonging to clonal complex 17 (CC17). We have previously shown that the prototypical CC17 BM110 strain invades polarized enterocyte-like cells through their lateral surfaces using an endocytic pathway. By analyzing the cellular distribution of putative GBS receptors in human enterocyte-like Caco-2 cells, we find here that the alpha 3 (α3) and alpha 2 (α2) integrin subunits are selectively expressed on lateral enterocyte surfaces at equatorial and parabasal levels along the vertical axis of polarized cells, in an area corresponding to GBS entry sites. The α3β1 and α2β1 integrins were not readily accessible in fully differentiated Caco-2 monolayers but could be exposed to specific antibodies after weakening of intercellular junctions in calcium-free media. Under these conditions, anti-α3β1 and anti-α2β1 antibodies significantly reduced GBS adhesion to and invasion of enterocytes. After endocytosis, α3β1 and α2β1 integrins localized to areas of actin remodeling around GBS containing vacuoles. Taken together, these data indicate that GBS can invade enterocytes by binding to α3β1 and α2β1 integrins on the lateral membrane of polarized enterocytes, resulting in cytoskeletal remodeling and bacterial internalization. Blocking integrins might represent a viable strategy to prevent GBS invasion of gut epithelial tissues.
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Affiliation(s)
| | - Germana Lentini
- Department of Human Pathology, University of Messina, Messina, Italy
| | - Francesco Coppolino
- Department of Biomedical, Dental and Imaging Sciences, University of Messina, Messina, Italy
| | - Agata Famà
- Department of Human Pathology, University of Messina, Messina, Italy
| | - Giampiero Pietrocola
- Department of Molecular Medicine, Biochemistry Section, University of Pavia, Pavia, Italy
| | - Concetta Beninati
- Department of Human Pathology, University of Messina, Messina, Italy
- Scylla Biotech Srl, Messina, Italy
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Carossino M, Vissani MA, Barrandeguy ME, Balasuriya UBR, Parreño V. Equine Rotavirus A under the One Health Lens: Potential Impacts on Public Health. Viruses 2024; 16:130. [PMID: 38257830 PMCID: PMC10819593 DOI: 10.3390/v16010130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 12/29/2023] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Group A rotaviruses are a well-known cause of viral gastroenteritis in infants and children, as well as in many mammalian species and birds, affecting them at a young age. This group of viruses has a double-stranded, segmented RNA genome with high genetic diversity linked to point mutations, recombination, and, importantly, reassortment. While initial molecular investigations undertaken in the 1900s suggested host range restriction among group A rotaviruses based on the fact that different gene segments were distributed among different animal species, recent molecular surveillance and genome constellation genotyping studies conducted by the Rotavirus Classification Working Group (RCWG) have shown that animal rotaviruses serve as a source of diversification of human rotavirus A, highlighting their zoonotic potential. Rotaviruses occurring in various animal species have been linked with contributing genetic material to human rotaviruses, including horses, with the most recent identification of equine-like G3 rotavirus A infecting children. The goal of this article is to review relevant information related to rotavirus structure/genomic organization, epidemiology (with a focus on human and equine rotavirus A), evolution, inter-species transmission, and the potential zoonotic role of equine and other animal rotaviruses. Diagnostics, surveillance and the current status of human and livestock vaccines against RVA are also reviewed.
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Affiliation(s)
- Mariano Carossino
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA;
- Louisiana Animal Disease Diagnostic Laboratory, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Maria Aldana Vissani
- Escuela de Veterinaria, Facultad de Ciencias Agrarias y Veterinarias, Universidad del Salvador, Pilar, Buenos Aires B1630AHU, Argentina; (M.A.V.); (M.E.B.)
- Instituto de Virología, CICVyA, Instituto Nacional de Tecnología Agropecuaria (INTA), Buenos Aires B1686LQF, Argentina;
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1033AAJ, Argentina
| | - Maria E. Barrandeguy
- Escuela de Veterinaria, Facultad de Ciencias Agrarias y Veterinarias, Universidad del Salvador, Pilar, Buenos Aires B1630AHU, Argentina; (M.A.V.); (M.E.B.)
- Instituto de Virología, CICVyA, Instituto Nacional de Tecnología Agropecuaria (INTA), Buenos Aires B1686LQF, Argentina;
| | - Udeni B. R. Balasuriya
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA;
- Louisiana Animal Disease Diagnostic Laboratory, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Viviana Parreño
- Instituto de Virología, CICVyA, Instituto Nacional de Tecnología Agropecuaria (INTA), Buenos Aires B1686LQF, Argentina;
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1033AAJ, Argentina
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Liu W, Xu Z, Qiu Y, Qiu X, Tan L, Song C, Sun Y, Liao Y, Liu X, Ding C. Single-Cell Transcriptome Atlas of Newcastle Disease Virus in Chickens Both In Vitro and In Vivo. Microbiol Spectr 2023; 11:e0512122. [PMID: 37191506 PMCID: PMC10269786 DOI: 10.1128/spectrum.05121-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 03/28/2023] [Indexed: 05/17/2023] Open
Abstract
Newcastle disease virus (NDV) is an avian paramyxovirus that causes major economic losses to the poultry industry around the world, with NDV pathogenicity varying due to strain virulence differences. However, the impacts of intracellular viral replication and the heterogeneity of host responses among cell types are unknown. Here, we investigated the heterogeneity of lung tissue cells in response to NDV infection in vivo and that of the chicken embryo fibroblast cell line DF-1 in response to NDV infection in vitro using single-cell RNA sequencing. We characterized the NDV target cell types in the chicken lung at the single-cell transcriptome level and classified cells into five known and two unknown cell types. The five known cell types are the targets of NDV in the lungs with virus RNA detected. Different paths of infection in the putative trajectories of NDV infection were distinguished between in vivo and in vitro, or between virulent Herts/33 strain and nonvirulent LaSota strain. Gene expression patterns and the interferon (IFN) response in different putative trajectories were demonstrated. IFN responses were elevated in vivo, especially in myeloid and endothelial cells. We distinguished the virus-infected and non-infected cells, and the Toll-like receptor signaling pathway was the main pathway after virus infection. Cell-cell communication analysis revealed the potential cell surface receptor-ligand of NDV. Our data provide a rich resource for understanding NDV pathogenesis and open the way to interventions specifically targeting infected cells. IMPORTANCE Newcastle disease virus (NDV) is an avian paramyxovirus that causes major economic losses to the poultry industry around the world, with NDV pathogenicity varying due to strain virulence differences. However, the impacts of intracellular viral replication and the heterogeneity of host responses among cell types are unknown. Here, we investigated the heterogeneity of lung tissue cells in response to NDV infection in vivo and that of the chicken embryo fibroblast cell line DF-1 in response to NDV infection in vitro using single-cell RNA sequencing. Our results open the way to interventions specifically targeting infected cells, suggest principles of virus-host interactions applicable to NDV and other similar pathogens, and highlight the potential for simultaneous single-cell measurements of both host and viral transcriptomes for delineating a comprehensive map of infection in vitro and in vivo. Therefore, this study can be a useful resource for the further investigation and understanding of NDV.
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Affiliation(s)
- Weiwei Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Zejun Xu
- School of Food and Bioengineering, Wuhu Institute of Technology, Wuhu, China
| | - Yafeng Qiu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Xusheng Qiu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Lei Tan
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Cuiping Song
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Yingjie Sun
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Ying Liao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Xiufan Liu
- School of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
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Abstract
Rotavirus (RV), the most common cause of gastroenteritis in children, carries a high economic and health burden worldwide. RV encodes six structural proteins and six nonstructural proteins (NSPs) that play different roles in viral replication. NSP4, a multifunctional protein involved in various viral replication processes, has two conserved N-glycosylation sites; however, the role of glycans remains elusive. Here, we used recombinant viruses generated by a reverse genetics system to determine the role of NSP4 N-glycosylation during viral replication and pathogenesis. The growth rate of recombinant viruses that lost one glycosylation site was as high as that of the wild-type virus. However, a recombinant virus that lost both glycosylation sites (glycosylation-defective virus) showed attenuated replication in cultured cell lines. Specifically, replications of glycosylation-defective virus in MA104 and HT29 cells were 10- and 100,000-fold lower, respectively, than that of the wild-type, suggesting that N-glycosylation of NSP4 plays a critical role in RV replication. The glycosylation-defective virus showed NSP4 mislocalization, delay of cytosolic Ca2+ elevation, and less viroplasm formation in MA104 cells; however, these impairments were not observed in HT29 cells. Further analysis revealed that assembly of glycosylation-defective virus was severely impaired in HT29 cells but not in MA104 cells, suggesting that RV replication mechanism is highly cell type dependent. In vivo mouse experiments also showed that the glycosylation-defective virus was less pathogenic than the wild-type virus. Taken together, the data suggest that N-glycosylation of NSP4 plays a vital role in viral replication and pathogenicity. IMPORTANCE Rotavirus is the main cause of gastroenteritis in young children and infants worldwide, contributing to 128,500 deaths each year. Here, we used a reverse genetics approach to examine the role of NSP4 N-glycosylation. An N-glycosylation-defective virus showed attenuated and cell-type-dependent replication in vitro. In addition, mice infected with the N-glycosylation-defective virus had less severe diarrhea than mice infected with the wild type. These results suggest that N-glycosylation affects viral replication and pathogenesis. Considering the reduced pathogenicity in vivo and the high propagation rate in MA104 cells, this glycosylation-defective virus could be an ideal live attenuated vaccine candidate.
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Huang H, Liao D, He B, Cui Y, Pu R, Zhou G. Calcium-sensing receptor acts as an antiviral factor for rotavirus infections and participates in cellular antiviral response. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2022; 25:997-1001. [PMID: 36159337 PMCID: PMC9464346 DOI: 10.22038/ijbms.2022.64533.14201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 07/20/2022] [Indexed: 11/24/2022]
Abstract
OBJECTIVES Rotavirus (RV) is one of the most significant pathogens associated with childhood diarrhoeal deaths worldwide. Elevated cytoplasmic calcium is required for RV replication, but the underlying mechanisms responsible for calcium influx remain poorly understood. The Calcium-sensing receptor (CaSR) is an important Ca2+ sensor that regulates the transport of Ca2+ into or out of the extracellular space by affecting the status of Ca2+ ion channels on the membrane of cells. Currently, the function of CaSR in RV replication is unclear. MATERIALS AND METHODS We evaluated the mRNA and protein levels of CaSR in RV-infected cells using qRT-PCR and Western blotting, respectively. Furthermore, we silenced or overexpressed CaSR in Caco-2 cells using siRNA or a CaSR gene contained adenovirus (Adv-CaSR). qRT-PCR, plaque assay, and Western blotting were used to determine the synthesis of virus genomic RNA, production of progeny virion, and the levels of viral proteins. The content of Ca2+ in cells was observed under confocal microscopy. RESULTS Compared with control cells, the RV-infected cells presented significantly decreased CaSR expression. Moreover, adenoviral-mediated over-expression or induction of CaSR by R568 greatly inhibited the RV RNA synthesis, protein expression, and formation of viroplasm plaques, thereby suppressing RV replication. In contrast, CaSR-silenced cells exhibited significantly enhanced RV replication. Compared with the Adv-Control group, the concentration of cytosolic Ca2+ significantly decreased in the Adv-CaSR group. CONCLUSION These findings demonstrated that CaSR is a potential target for inhibition of RV replication. Therefore, enhancing the expression of CaSR might protect hosts from RV infections.
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Affiliation(s)
- Haohai Huang
- Department of Clinical Pharmacy, SSL Central Hospital of Dongguan, Dongguan Third People’s Hospital, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China.,Medical and Pharmacy Research Laboratory, SSL Central Hospital of Dongguan, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China,These authors contributed equally to this work
| | - Dan Liao
- Department of Gynaecology, SSL Central Hospital of Dongguan, Dongguan Third People’s Hospital, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China,These authors contributed equally to this work
| | - Bin He
- Central Laboratory, SSL Central Hospital of Dongguan, Dongguan Third People’s Hospital, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China
| | - Yejia Cui
- Department of Clinical Laboratory, SSL Central Hospital of Dongguan City, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China
| | - Rong Pu
- Department of Clinical Laboratory, SSL Central Hospital of Dongguan City, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China,responding authors: Rong Pu. Department of Clinical Laboratory, SSL Central Hospital of Dongguan, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, No.1, Huangzhou Xianglong Road of Shilong Town, Dongguan, Guangdong, 523326, China. Tel: +86-18002900838; Fax: 86-0769-81368802; , Guanghui Zhou. Department of Rehabilitation medicine, SSL Central Hospital of Dongguan, Dongguan Third People’s Hospital, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China. Tel: +86-13650492072; Fax: 86-0769-81368802;
| | - Guanghui Zhou
- Department of Rehabilitation medicine, SSL Central Hospital of Dongguan, Dongguan Third People’s Hospital, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China,responding authors: Rong Pu. Department of Clinical Laboratory, SSL Central Hospital of Dongguan, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, No.1, Huangzhou Xianglong Road of Shilong Town, Dongguan, Guangdong, 523326, China. Tel: +86-18002900838; Fax: 86-0769-81368802; , Guanghui Zhou. Department of Rehabilitation medicine, SSL Central Hospital of Dongguan, Dongguan Third People’s Hospital, Affiliated Dongguan Shilong People’s Hospital of Southern Medical University, Dongguan, Guangdong, China. Tel: +86-13650492072; Fax: 86-0769-81368802;
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6
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Mwangi PN, Page NA, Seheri ML, Mphahlele MJ, Nadan S, Esona MD, Kumwenda B, Kamng'ona AW, Donato CM, Steele DA, Ndze VN, Dennis FE, Jere KC, Nyaga MM. Evolutionary changes between pre- and post-vaccine South African group A G2P[4] rotavirus strains, 2003-2017. Microb Genom 2022; 8. [PMID: 35446251 PMCID: PMC9453071 DOI: 10.1099/mgen.0.000809] [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: 11/18/2022] Open
Abstract
The transient upsurge of G2P[4] group A rotavirus (RVA) after Rotarix vaccine introduction in several countries has been a matter of concern. To gain insight into the diversity and evolution of G2P[4] strains in South Africa pre- and post-RVA vaccination introduction, whole-genome sequencing was performed for RVA positive faecal specimens collected between 2003 and 2017 and samples previously sequenced were obtained from GenBank (n=103; 56 pre- and 47 post-vaccine). Pre-vaccine G2 sequences predominantly clustered within sub-lineage IVa-1. In contrast, post-vaccine G2 sequences clustered mainly within sub-lineage IVa-3, whereby a radical amino acid (AA) substitution, S15F, was observed between the two sub-lineages. Pre-vaccine P[4] sequences predominantly segregated within sub-lineage IVa while post-vaccine sequences clustered mostly within sub-lineage IVb, with a radical AA substitution R162G. Both S15F and R162G occurred outside recognised antigenic sites. The AA residue at position 15 is found within the signal sequence domain of Viral Protein 7 (VP7) involved in translocation of VP7 into endoplasmic reticulum during infection process. The 162 AA residue lies within the hemagglutination domain of Viral Protein 4 (VP4) engaged in interaction with sialic acid-containing structure during attachment to the target cell. Free energy change analysis on VP7 indicated accumulation of stable point mutations in both antigenic and non-antigenic regions. The segregation of South African G2P[4] strains into pre- and post-vaccination sub-lineages is likely due to erstwhile hypothesized stepwise lineage/sub-lineage evolution of G2P[4] strains rather than RVA vaccine introduction. Our findings reinforce the need for continuous whole-genome RVA surveillance and investigation of contribution of AA substitutions in understanding the dynamic G2P[4] epidemiology.
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Affiliation(s)
- Peter N Mwangi
- Next Generation Sequencing Unit and Division of Virology, Faculty of Health Sciences, University of the Free State, Bloemfontein 9300, South Africa
| | - Nicola A Page
- Centre for Enteric Disease, National Institute for Communicable Diseases, Private Bag X4, Sandringham, 2131, Johannesburg, South Africa.,Department of Medical Virology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, 0007, Pretoria, South Africa
| | - Mapaseka L Seheri
- Diarrheal Pathogens Research Unit, Sefako Makgatho Health Sciences University, Medunsa 0204, Pretoria, South Africa
| | - M Jeffrey Mphahlele
- Diarrheal Pathogens Research Unit, Sefako Makgatho Health Sciences University, Medunsa 0204, Pretoria, South Africa.,Office of the Deputy Vice Chancellor for Research and Innovation, North-West University, Potchefstroom 2351, South Africa.,South African Medical Research Council, Pretoria 0001, South Africa
| | - Sandrama Nadan
- Centre for Enteric Disease, National Institute for Communicable Diseases, Private Bag X4, Sandringham, 2131, Johannesburg, South Africa
| | - Mathew D Esona
- Diarrheal Pathogens Research Unit, Sefako Makgatho Health Sciences University, Medunsa 0204, Pretoria, South Africa
| | - Benjamin Kumwenda
- Department of Biomedical Sciences, School of Life Sciences and Applied Health Professions, Kamuzu University of Health Sciences, Private Bag 360, Chichiri, Blantyre 3, Malawi
| | - Arox W Kamng'ona
- Department of Biomedical Sciences, School of Life Sciences and Applied Health Professions, Kamuzu University of Health Sciences, Private Bag 360, Chichiri, Blantyre 3, Malawi
| | - Celeste M Donato
- Department of Medical Laboratory Sciences, School of Life Sciences and Applied Health Professions, Kamuzu University of Health Sciences, Private Bag 360, Chichiri, Blantyre3, Malawi.,Enteric Diseases Group, Murdoch Children's Research Institute, 50 Flemington Road, Parkville, Melboune 3052, Australia.,Department of Paediatrics, the University of Melbourne, Parkville 3010, Australia
| | - Duncan A Steele
- Diarrheal Pathogens Research Unit, Sefako Makgatho Health Sciences University, Medunsa 0204, Pretoria, South Africa
| | - Valantine N Ndze
- Faculty of Health Sciences, University of Buea, P.O Box 63 Buea, Cameroon
| | - Francis E Dennis
- Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O Box LG581, Legon, Ghana
| | - Khuzwayo C Jere
- Center for Global Vaccine Research, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, L697BE, Liverpool, UK.,Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre 312225, Malawi
| | - Martin M Nyaga
- Next Generation Sequencing Unit and Division of Virology, Faculty of Health Sciences, University of the Free State, Bloemfontein 9300, South Africa
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Omatola CA, Olaniran AO. Rotaviruses: From Pathogenesis to Disease Control—A Critical Review. Viruses 2022; 14:v14050875. [PMID: 35632617 PMCID: PMC9143449 DOI: 10.3390/v14050875] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 12/16/2022] Open
Abstract
Since their first recognition in human cases about four decades ago, rotaviruses have remained the leading cause of acute severe dehydrating diarrhea among infants and young children worldwide. The WHO prequalification of oral rotavirus vaccines (ORV) a decade ago and its introduction in many countries have yielded a significant decline in the global burden of the disease, although not without challenges to achieving global effectiveness. Poised by the unending malady of rotavirus diarrhea and the attributable death cases in developing countries, we provide detailed insights into rotavirus biology, exposure pathways, cellular receptors and pathogenesis, host immune response, epidemiology, and vaccination. Additionally, recent developments on the various host, viral and environmental associated factors impacting ORV performance in low-and middle-income countries (LMIC) are reviewed and their significance assessed. In addition, we review the advances in nonvaccine strategies (probiotics, candidate anti-rotaviral drugs, breastfeeding) to disease prevention and management.
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8
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Melnik LI, Garry RF. Enterotoxigenic Escherichia coli Heat-Stable Toxin and Ebola Virus Delta Peptide: Similarities and Differences. Pathogens 2022; 11:pathogens11020170. [PMID: 35215114 PMCID: PMC8878840 DOI: 10.3390/pathogens11020170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/22/2022] [Accepted: 01/24/2022] [Indexed: 01/27/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) STb toxin exhibits striking structural similarity to Ebola virus (EBOV) delta peptide. Both ETEC and EBOV delta peptide are enterotoxins. Comparison of the structural and functional similarities and differences of these two toxins illuminates features that are important in induction of pathogenesis by a bacterial and viral pathogen.
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Affiliation(s)
- Lilia I. Melnik
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA;
- Viral Hemorrhagic Fever Consortium, New Orleans, LA 70112, USA
- Correspondence: ; Tel.: +1-(504)988-3818
| | - Robert F. Garry
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA 70112, USA;
- Viral Hemorrhagic Fever Consortium, New Orleans, LA 70112, USA
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Chang-Graham AL, Perry JL, Engevik MA, Engevik KA, Scribano FJ, Gebert JT, Danhof HA, Nelson JC, Kellen JS, Strtak AC, Sastri NP, Estes MK, Britton RA, Versalovic J, Hyser JM. Rotavirus induces intercellular calcium waves through ADP signaling. Science 2020; 370:370/6519/eabc3621. [PMID: 33214249 PMCID: PMC7957961 DOI: 10.1126/science.abc3621] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 10/16/2020] [Indexed: 01/14/2023]
Abstract
Rotavirus causes severe diarrheal disease in children by broadly dysregulating intestinal homeostasis. However, the underlying mechanism(s) of rotavirus-induced dysregulation remains unclear. We found that rotavirus-infected cells produce paracrine signals that manifested as intercellular calcium waves (ICWs), observed in cell lines and human intestinal enteroids. Rotavirus ICWs were caused by the release of extracellular adenosine 5'-diphosphate (ADP) that activated P2Y1 purinergic receptors on neighboring cells. ICWs were blocked by P2Y1 antagonists or CRISPR-Cas9 knockout of the P2Y1 receptor. Blocking the ADP signal reduced rotavirus replication, inhibited rotavirus-induced serotonin release and fluid secretion, and reduced diarrhea severity in neonatal mice. Thus, rotavirus exploited paracrine purinergic signaling to generate ICWs that amplified the dysregulation of host cells and altered gastrointestinal physiology to cause diarrhea.
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Affiliation(s)
- Alexandra L. Chang-Graham
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - Jacob L. Perry
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - Melinda A. Engevik
- Department of Pathology and Immunology, Baylor College of Medicine, USA,Department of Pathology, Texas Children’s Hospital, USA
| | - Kristen A. Engevik
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - Francesca J. Scribano
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - J. Thomas Gebert
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - Heather A. Danhof
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - Joel C. Nelson
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA
| | - Joseph S. Kellen
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - Alicia C. Strtak
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - Narayan P. Sastri
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA
| | - Mary K. Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA,Department of Medicine, Gastroenterology and Hepatology, Baylor College of Medicine, USA
| | - Robert A. Britton
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA
| | - James Versalovic
- Department of Pathology and Immunology, Baylor College of Medicine, USA,Department of Pathology, Texas Children’s Hospital, USA
| | - Joseph M. Hyser
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, USA,Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, USA,Corresponding author. Correspondence and requests for materials should be addressed to J.H.
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10
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Huang H, Pu Y, Liao D, Zhu Z, Wang J, Cui Y. The expression of calcium-sensing receptor during rotavirus induced diarrhea in neonatal mice. GAZZETTA MEDICA ITALIANA ARCHIVIO PER LE SCIENZE MEDICHE 2019. [DOI: 10.23736/s0393-3660.18.03910-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Rao MC. Physiology of Electrolyte Transport in the Gut: Implications for Disease. Compr Physiol 2019; 9:947-1023. [PMID: 31187895 DOI: 10.1002/cphy.c180011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We now have an increased understanding of the genetics, cell biology, and physiology of electrolyte transport processes in the mammalian intestine, due to the availability of sophisticated methodologies ranging from genome wide association studies to CRISPR-CAS technology, stem cell-derived organoids, 3D microscopy, electron cryomicroscopy, single cell RNA sequencing, transgenic methodologies, and tools to manipulate cellular processes at a molecular level. This knowledge has simultaneously underscored the complexity of biological systems and the interdependence of multiple regulatory systems. In addition to the plethora of mammalian neurohumoral factors and their cross talk, advances in pyrosequencing and metagenomic analyses have highlighted the relevance of the microbiome to intestinal regulation. This article provides an overview of our current understanding of electrolyte transport processes in the small and large intestine, their regulation in health and how dysregulation at multiple levels can result in disease. Intestinal electrolyte transport is a balance of ion secretory and ion absorptive processes, all exquisitely dependent on the basolateral Na+ /K+ ATPase; when this balance goes awry, it can result in diarrhea or in constipation. The key transporters involved in secretion are the apical membrane Cl- channels and the basolateral Na+ -K+ -2Cl- cotransporter, NKCC1 and K+ channels. Absorption chiefly involves apical membrane Na+ /H+ exchangers and Cl- /HCO3 - exchangers in the small intestine and proximal colon and Na+ channels in the distal colon. Key examples of our current understanding of infectious, inflammatory, and genetic diarrheal diseases and of constipation are provided. © 2019 American Physiological Society. Compr Physiol 9:947-1023, 2019.
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Affiliation(s)
- Mrinalini C Rao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois, USA
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12
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Abstract
Viroporins are short polypeptides encoded by viruses. These small membrane proteins assemble into oligomers that can permeabilize cellular lipid bilayers, disrupting the physiology of the host to the advantage of the virus. Consequently, efforts during the last few decades have been focused towards the discovery of viroporin channel inhibitors, but in general these have not been successful to produce licensed drugs. Viroporins are also involved in viral pathogenesis by engaging in critical interactions with viral proteins, or disrupting normal host cellular pathways through coordinated interactions with host proteins. These protein-protein interactions (PPIs) may become alternative attractive drug targets for the development of antivirals. In this sense, while thus far most antiviral molecules have targeted viral proteins, focus is moving towards targeting host proteins that are essential for virus replication. In principle, this largely would overcome the problem of resistance, with the possibility of using repositioned existing drugs. The precise role of these PPIs, their strain- and host- specificities, and the structural determination of the complexes involved, are areas that will keep the fields of virology and structural biology occupied for years to come. In the present review, we provide an update of the efforts in the characterization of the main PPIs for most viroporins, as well as the role of viroporins in these PPIs interactions.
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Affiliation(s)
| | - David Bhella
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
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Kumar S, Ramappa R, Pamidimukkala K, Rao CD, Suguna K. New tetrameric forms of the rotavirus NSP4 with antiparallel helices. Arch Virol 2018; 163:1531-1547. [DOI: 10.1007/s00705-018-3753-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 01/13/2018] [Indexed: 01/05/2023]
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Abstract
Rotavirus infections are a leading cause of severe, dehydrating gastroenteritis in children <5 years of age. Despite the global introduction of vaccinations for rotavirus over a decade ago, rotavirus infections still result in >200,000 deaths annually, mostly in low-income countries. Rotavirus primarily infects enterocytes and induces diarrhoea through the destruction of absorptive enterocytes (leading to malabsorption), intestinal secretion stimulated by rotavirus non-structural protein 4 and activation of the enteric nervous system. In addition, rotavirus infections can lead to antigenaemia (which is associated with more severe manifestations of acute gastroenteritis) and viraemia, and rotavirus can replicate in systemic sites, although this is limited. Reinfections with rotavirus are common throughout life, although the disease severity is reduced with repeat infections. The immune correlates of protection against rotavirus reinfection and recovery from infection are poorly understood, although rotavirus-specific immunoglobulin A has a role in both aspects. The management of rotavirus infection focuses on the prevention and treatment of dehydration, although the use of antiviral and anti-emetic drugs can be indicated in some cases.
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Xiong X, Hu Y, Liu C, Li X. Rotavirus NSP4 86-175 interacts with H9c2(2-1) cells in vitro, elevates intracellular Ca 2+ levels and can become cytotoxic: a possible mechanism for extra-intestinal pathogenesis. Virus Genes 2016; 53:179-189. [PMID: 28000081 DOI: 10.1007/s11262-016-1419-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 12/07/2016] [Indexed: 12/23/2022]
Abstract
Rotavirus (RV) is the predominant cause of infantile gastroenteritis with multiple pathogenic factors, among which enterotoxin NSP4 is the most significant factor. NSP4 has been shown to induce elevation of the intracellular calcium concentration, alteration of the cytoskeleton organization, and cytopathic effect among other processes. However, increasing evidence suggests that RVs can escape from the gastrointestinal tract and invade other organs and tissues to cause extra-intestinal diseases. In this study, we investigated whether NSP4 has a pathogenic effect on extra-intestinal cells and examined possible molecular mechanisms in vitro. Our results showed that NSP486-175 has important functions in increasing intracellular Ca2+ concentration, altering actin cytoskeleton organization and inducing cellular damage in H9c2(2-1) cells. Blockade of the integrin α2 receptor using a specific antibody attenuated the increase of intracellular Ca2+ concentration and alleviated the observed cytopathic effects, suggesting that integrin α2 may be a receptor for NSP486-175. Collectively, these results indicate that extracellular NSP486-175 can induce elevation of the intracellular Ca2+ concentration, cause cytotoxic changes, and disrupt the actin cytoskeleton in H9c2(2-1) cells, which may constitute a possible mechanism for RV extra-intestinal pathogenesis.
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Affiliation(s)
- Xiaoshun Xiong
- Department of Clinical Laboratory, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325027, Zhejiang, People's Republic of China
| | - Yinyin Hu
- Department of Clinical Laboratory, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325027, Zhejiang, People's Republic of China
| | - Caixia Liu
- Department of Clinical Laboratory, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325027, Zhejiang, People's Republic of China
| | - Xiangyang Li
- Department of Clinical Laboratory, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325027, Zhejiang, People's Republic of China.
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16
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Abstract
Eukaryotic cells have evolved a myriad of ion channels, transporters, and pumps to maintain and regulate transmembrane ion gradients. As intracellular parasites, viruses also have evolved ion channel proteins, called viroporins, which disrupt normal ionic homeostasis to promote viral replication and pathogenesis. The first viral ion channel (influenza M2 protein) was confirmed only 23 years ago, and since then studies on M2 and many other viroporins have shown they serve critical functions in virus entry, replication, morphogenesis, and immune evasion. As new candidate viroporins and viroporin-mediated functions are being discovered, we review the experimental criteria for viroporin identification and characterization to facilitate consistency within this field of research. Then we review recent studies on how the few Ca(2+)-conducting viroporins exploit host signaling pathways, including store-operated Ca(2+) entry, autophagy, and inflammasome activation. These viroporin-induced aberrant Ca(2+) signals cause pathophysiological changes resulting in diarrhea, vomiting, and proinflammatory diseases, making both the viroporin and host Ca(2+) signaling pathways potential therapeutic targets for antiviral drugs.
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Affiliation(s)
- Joseph M Hyser
- Alkek Center for Metagenomic and Microbiome Research.,Department of Molecular Virology and Microbiology, and
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, and.,Department of Medicine, Baylor College of Medicine, Houston, Texas 77030-3411;
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Sahmani M, Azari S, Tebianian M, Gheibi N, Pourasgari F. Higher Expression Level and Lower Toxicity of Genetically Spliced Rotavirus NSP4 in Comparison to the Full-Length Protein in E. coli. IRANIAN JOURNAL OF BIOTECHNOLOGY 2016; 14:50-57. [PMID: 28959326 DOI: 10.15171/ijb.1233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Rotavirus group A (RVA) is recognized as a major cause of severe gastroenteritis in children and new-born animals. Nonstructural protein 4 (NSP4) is responsible for the enterotoxic activity of these viruses in the villus epithelial cells. Amino acids 114-135 of NSP4 are known to form the diarrhea-inducing region of this viral enterotoxin. Therefore, developing an NSP4 lacking the enterotoxin domain could result in the introduction of a new subunit vaccine against rotaviruses in both humans and animals. OBJECTIVES The aim of this study is the evaluation of rotavirus A NSP4 expression in E. coli expression system before and after removal of the diarrhea-inducing domain, which is the first step towards further immunological studies of the resulting protein. MATERIALS AND METHODS Splicing by overlap extension (SOEing) PCR was used to remove the diarrhea-inducing sequence from the NSP4 cDNA. Both the full-length (FL-NSP4) and the spliced (S-NSP4) cDNA amplicons were cloned into pET-32c and pGEX-6P-2. Expression levels of the recombinant proteins were evaluated in E. coli BL21 (DE3) by Western blot analysis. In addition, the toxicity of pET plasmids bearing the S-NSP4 and FL-NSP4 fragments was investigated by plasmid stability test. RESULTS For FL-NSP4, protein expression was detected for the strain containing the pGEX:FL-NSP4 plasmid, but not for the strain carrying pET:FL-NSP4. Hourly sampling up to 3 h showed that the protein production decreased by time. In contrast, expression of S-NSP4 was detected for pET:S-NSP4 strain, but not for pGEX:S-NSP4. Plasmid stability test showed that pET:S-NSP4 recombinant plasmid was almost stable, while pET:FL-NSP4 was unstable. CONCLUSIONS This is the first report of production of rotavirus NSP4 lacking the diarrhea-inducing domain (S-NSP4). SNSP4 shows less toxicity in this expression system and potentially could be a promising goal for rotavirus immunological and vaccine studies in the future.
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Affiliation(s)
- Mehdi Sahmani
- Department of Clinical Biochemistry and Genetics, Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Siavash Azari
- Department of Biotechnology, School of Paramedical Sciences, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Majid Tebianian
- Department of Biotechnology, Razi Vaccine and Serum Research Institute, Karaj, Iran
| | - Nematollah Gheibi
- Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Farzaneh Pourasgari
- Department of Biotechnology, Razi Vaccine and Serum Research Institute, Karaj, Iran
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19
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Perry JL, Ramachandran NK, Utama B, Hyser JM. Use of genetically-encoded calcium indicators for live cell calcium imaging and localization in virus-infected cells. Methods 2015; 90:28-38. [PMID: 26344758 PMCID: PMC4655165 DOI: 10.1016/j.ymeth.2015.09.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 01/09/2023] Open
Abstract
Calcium signaling is a ubiquitous and versatile process involved in nearly every cellular process, and exploitation of host calcium signals is a common strategy used by viruses to facilitate replication and cause disease. Small molecule fluorescent calcium dyes have been used by many to examine changes in host cell calcium signaling and calcium channel activation during virus infections, but disadvantages of these dyes, including poor loading and poor long-term retention, complicate analysis of calcium imaging in virus-infected cells due to changes in cell physiology and membrane integrity. The recent expansion of genetically-encoded calcium indicators (GECIs), including blue and red-shifted color variants and variants with calcium affinities appropriate for calcium storage organelles like the endoplasmic reticulum (ER), make the use of GECIs an attractive alternative for calcium imaging in the context of virus infections. Here we describe the development and testing of cell lines stably expressing both green cytoplasmic (GCaMP5G and GCaMP6s) and red ER-targeted (RCEPIAer) GECIs. Using three viruses (rotavirus, poliovirus and respiratory syncytial virus) previously shown to disrupt host calcium homeostasis, we show the GECI cell lines can be used to detect simultaneous cytoplasmic and ER calcium signals. Further, we demonstrate the GECI expression has sufficient stability to enable long-term confocal imaging of both cytoplasmic and ER calcium during the course of virus infections.
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Affiliation(s)
- Jacob L Perry
- Department of Molecular Virology and Microbiology and Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, Houston, TX 77030, United States
| | - Nina K Ramachandran
- Department of Molecular Virology and Microbiology and Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, Houston, TX 77030, United States
| | - Budi Utama
- Shared Equipment Authority, Rice University, Houston, TX 77030, United States
| | - Joseph M Hyser
- Department of Molecular Virology and Microbiology and Alkek Center for Metagenomic and Microbiome Research, Baylor College of Medicine, Houston, TX 77030, United States.
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20
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Human Intestinal Enteroids: a New Model To Study Human Rotavirus Infection, Host Restriction, and Pathophysiology. J Virol 2015; 90:43-56. [PMID: 26446608 DOI: 10.1128/jvi.01930-15] [Citation(s) in RCA: 253] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 10/05/2015] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Human gastrointestinal tract research is limited by the paucity of in vitro intestinal cell models that recapitulate the cellular diversity and complex functions of human physiology and disease pathology. Human intestinal enteroid (HIE) cultures contain multiple intestinal epithelial cell types that comprise the intestinal epithelium (enterocytes and goblet, enteroendocrine, and Paneth cells) and are physiologically active based on responses to agonists. We evaluated these nontransformed, three-dimensional HIE cultures as models for pathogenic infections in the small intestine by examining whether HIEs from different regions of the small intestine from different patients are susceptible to human rotavirus (HRV) infection. Little is known about HRVs, as they generally replicate poorly in transformed cell lines, and host range restriction prevents their replication in many animal models, whereas many animal rotaviruses (ARVs) exhibit a broader host range and replicate in mice. Using HRVs, including the Rotarix RV1 vaccine strain, and ARVs, we evaluated host susceptibility, virus production, and cellular responses of HIEs. HRVs infect at higher rates and grow to higher titers than do ARVs. HRVs infect differentiated enterocytes and enteroendocrine cells, and viroplasms and lipid droplets are induced. Heterogeneity in replication was seen in HIEs from different patients. HRV infection and RV enterotoxin treatment of HIEs caused physiological lumenal expansion detected by time-lapse microscopy, recapitulating one of the hallmarks of rotavirus-induced diarrhea. These results demonstrate that HIEs are a novel pathophysiological model that will allow the study of HRV biology, including host restriction, cell type restriction, and virus-induced fluid secretion. IMPORTANCE Our research establishes HIEs as nontransformed cell culture models to understand human intestinal physiology and pathophysiology and the epithelial response, including host restriction of gastrointestinal infections such as HRV infection. HRVs remain a major worldwide cause of diarrhea-associated morbidity and mortality in children ≤5 years of age. Current in vitro models of rotavirus infection rely primarily on the use of animal rotaviruses because HRV growth is limited in most transformed cell lines and animal models. We demonstrate that HIEs are novel, cellularly diverse, and physiologically relevant epithelial cell cultures that recapitulate in vivo properties of HRV infection. HIEs will allow the study of HRV biology, including human host-pathogen and live, attenuated vaccine interactions; host and cell type restriction; virus-induced fluid secretion; cell-cell communication within the epithelium; and the epithelial response to infection in cultures from genetically diverse individuals. Finally, drug therapies to prevent/treat diarrheal disease can be tested in these physiologically active cultures.
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21
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Hussein HAM, Walker LR, Abdel-Raouf UM, Desouky SA, Montasser AKM, Akula SM. Beyond RGD: virus interactions with integrins. Arch Virol 2015; 160:2669-81. [PMID: 26321473 PMCID: PMC7086847 DOI: 10.1007/s00705-015-2579-8] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022]
Abstract
Viruses successfully infect host cells by initially binding to the surfaces of the cells, followed by an intricate entry process. As multifunctional heterodimeric cell-surface receptor molecules, integrins have been shown to usefully serve as entry receptors for a plethora of viruses. However, the exact role(s) of integrins in viral pathogen internalization has yet to be elaborately described. Notably, several viruses harbor integrin-recognition motifs displayed on viral envelope/capsid-associated proteins. The most common of these motifs is the minimal peptide sequence for binding integrins, RGD (Arg-Gly-Asp), which is known for its role in virus infection via its ability to interact with over half of the more than 20 known integrins. Not all virus-integrin interactions are RGD-dependent, however. Non-RGD-binding integrins have also been shown to effectively promote virus entry and infection as well. Such virus-integrin binding is shown to facilitate adhesion, cytoskeleton rearrangement, integrin activation, and increased intracellular signaling. Also, we have attempted to discuss the role of carbohydrate moieties in virus interactions with receptor-like host cell surface integrins that drive the process of internalization. As much as possible, this article examines the published literature regarding the role of integrins in terms of virus infection and virus-encoded glycosylated proteins that mediate interactions with integrins, and it explores the idea of targeting these receptors as a therapeutic treatment option.
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Affiliation(s)
- Hosni A M Hussein
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA
| | - Lia R Walker
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA
| | - Usama M Abdel-Raouf
- Faculty of Science, Al Azhar University, Assiut Branch, Assiut, 71524, Egypt
| | - Sayed A Desouky
- Faculty of Science, Al Azhar University, Assiut Branch, Assiut, 71524, Egypt
| | | | - Shaw M Akula
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA.
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Abstract
Diarrhoeal disease remains a major health burden worldwide. Secretory diarrhoeas are caused by certain bacterial and viral infections, inflammatory processes, drugs and genetic disorders. Fluid secretion across the intestinal epithelium in secretory diarrhoeas involves multiple ion and solute transporters, as well as activation of cyclic nucleotide and Ca(2+) signalling pathways. In many secretory diarrhoeas, activation of Cl(-) channels in the apical membrane of enterocytes, including the cystic fibrosis transmembrane conductance regulator and Ca(2+)-activated Cl(-) channels, increases fluid secretion, while inhibition of Na(+) transport reduces fluid absorption. Current treatment of diarrhoea includes replacement of fluid and electrolyte losses using oral rehydration solutions, and drugs targeting intestinal motility or fluid secretion. Therapeutics in the development pipeline target intestinal ion channels and transporters, regulatory proteins and cell surface receptors. This Review describes pathogenic mechanisms of secretory diarrhoea, current and emerging therapeutics, and the challenges in developing antidiarrhoeal therapeutics.
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Affiliation(s)
- Jay R Thiagarajah
- Division of Gastroenterology, Hepatology and Nutrition, Children's Hospital Boston, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Mark Donowitz
- Departments of Physiology and Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Ross 925, 720 Rutland Avenue, Baltimore, MD 21205, USA
| | - Alan S Verkman
- Departments of Medicine and Physiology, 1246 Health Sciences East Tower, University of California, 500 Parnassus Avenue, San Francisco, CA 94143, USA
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Viral Membrane Channels: Role and Function in the Virus Life Cycle. Viruses 2015; 7:3261-84. [PMID: 26110585 PMCID: PMC4488738 DOI: 10.3390/v7062771] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 05/20/2015] [Accepted: 06/12/2015] [Indexed: 12/23/2022] Open
Abstract
Viroporins are small, hydrophobic trans-membrane viral proteins that oligomerize to form hydrophilic pores in the host cell membranes. These proteins are crucial for the pathogenicity and replication of viruses as they aid in various stages of the viral life cycle, from genome uncoating to viral release. In addition, the ion channel activity of viroporin causes disruption in the cellular ion homeostasis, in particular the calcium ion. Fluctuation in the calcium level triggers the activation of the host defensive programmed cell death pathways as well as the inflammasome, which in turn are being subverted for the viruses’ replication benefits. This review article summarizes recent developments in the functional investigation of viroporins from various viruses and their contributions to viral replication and virulence.
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24
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Abstract
UNLABELLED Rotavirus (RV) nonstructural protein 4 (NSP4) is a virulence factor that disrupts cellular Ca(2+) homeostasis and plays multiple roles regulating RV replication and the pathophysiology of RV-induced diarrhea. Although its native oligomeric state is unclear, crystallographic studies of the coiled-coil domain (CCD) of NSP4 from two different strains suggest that it functions as a tetramer or a pentamer. While the CCD of simian strain SA11 NSP4 forms a tetramer that binds Ca(2+) at its core, the CCD of human strain ST3 forms a pentamer lacking the bound Ca(2+) despite the residues (E120 and Q123) that coordinate Ca(2+) binding being conserved. In these previous studies, while the tetramer crystallized at neutral pH, the pentamer crystallized at low pH, suggesting that preference for a particular oligomeric state is pH dependent and that pH could influence Ca(2+) binding. Here, we sought to examine if the CCD of NSP4 from a single RV strain can exist in two oligomeric states regulated by Ca(2+) or pH. Biochemical, biophysical, and crystallographic studies show that while the CCD of SA11 NSP4 exhibits high-affinity binding to Ca(2+) at neutral pH and forms a tetramer, it does not bind Ca(2+) at low pH and forms a pentamer, and the transition from tetramer to pentamer is reversible with pH. Mutational analysis shows that Ca(2+) binding is necessary for the tetramer formation, as an E120A mutant forms a pentamer. We propose that the structural plasticity of NSP4 regulated by pH and Ca(2+) may form a basis for its pleiotropic functions during RV replication. IMPORTANCE The nonstructural protein NSP4 of rotavirus is a multifunctional protein that plays an important role in virus replication, morphogenesis, and pathogenesis. Previous crystallography studies of the coiled-coil domain (CCD) of NSP4 from two different rotavirus strains showed two distinct oligomeric states, a Ca(2+)-bound tetrameric state and a Ca(2+)-free pentameric state. Whether NSP4 CCD from the same strain can exist in different oligomeric states and what factors might regulate its oligomeric preferences are not known. This study used a combination of biochemical, biophysical, and crystallography techniques and found that the NSP4 CCD can undergo a reversible transition from a Ca(2+)-bound tetramer to a Ca(2+)-free pentamer in response to changes in pH. From these studies, we hypothesize that this remarkable structural adaptability of the CCD forms a basis for the pleiotropic functional properties of NSP4.
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25
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Desselberger U. Rotaviruses. Virus Res 2014; 190:75-96. [DOI: 10.1016/j.virusres.2014.06.016] [Citation(s) in RCA: 240] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 06/26/2014] [Accepted: 06/26/2014] [Indexed: 01/12/2023]
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Ko EA, Jin BJ, Namkung W, Ma T, Thiagarajah JR, Verkman AS. Chloride channel inhibition by a red wine extract and a synthetic small molecule prevents rotaviral secretory diarrhoea in neonatal mice. Gut 2014; 63:1120-9. [PMID: 24052273 PMCID: PMC4048772 DOI: 10.1136/gutjnl-2013-305663] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Rotavirus is the most common cause of severe secretory diarrhoea in infants and young children globally. The rotaviral enterotoxin, NSP4, has been proposed to stimulate calcium-activated chloride channels (CaCC) on the apical plasma membrane of intestinal epithelial cells. We previously identified red wine and small molecule CaCC inhibitors. OBJECTIVE To investigate the efficacy of a red wine extract and a synthetic small molecule, CaCCinh-A01, in inhibiting intestinal CaCCs and rotaviral diarrhoea. DESIGN Inhibition of CaCC-dependent current was measured in T84 cells and mouse ileum. The effectiveness of an orally administered wine extract and CaCCinh-A01 in inhibiting diarrhoea in vivo was determined in a neonatal mouse model of rotaviral infection. RESULTS Screening of ∼150 red wines revealed a Cabernet Sauvignon that inhibited CaCC current in T84 cells with IC50 at a ∼1:200 dilution, and higher concentrations producing 100% inhibition. A >1 kdalton wine extract prepared by dialysis, which retained full inhibition activity, blocked CaCC current in T84 cells and mouse intestine. In rotavirus-inoculated mice, oral administration of the wine extract prevented diarrhoea by inhibition of intestinal fluid secretion without affecting rotaviral infection. The wine extract did not inhibit the cystic fibrosis chloride channel (CFTR) in cell cultures, nor did it prevent watery stools in neonatal mice administered cholera toxin, which activates CFTR-dependent fluid secretion. CaCCinh-A01 also inhibited rotaviral diarrhoea. CONCLUSIONS Our results support a pathogenic role for enterocyte CaCCs in rotaviral diarrhoea and demonstrate the antidiarrhoeal action of CaCC inhibition by an alcohol-free, red wine extract and by a synthetic small molecule.
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Affiliation(s)
- Eun-A Ko
- Departments of Medicine and Physiology, University of California, San Francisco, California, USA
| | - Byung-Ju Jin
- Departments of Medicine and Physiology, University of California, San Francisco, California, USA
| | - Wan Namkung
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, Korea
| | - Tonghui Ma
- Department of Physiology, Dalian Medical University, Dalian, China
| | - Jay R. Thiagarajah
- Department of Gastroenterology, Hepatology and Nutrition, Children’s Hospital, Boston, Harvard Medical School, Boston, Massachusetts, USA
| | - A. S. Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, California, USA
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Tradtrantip L, Ko EA, Verkman AS. Antidiarrheal efficacy and cellular mechanisms of a Thai herbal remedy. PLoS Negl Trop Dis 2014; 8:e2674. [PMID: 24551253 PMCID: PMC3923670 DOI: 10.1371/journal.pntd.0002674] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 12/17/2013] [Indexed: 01/31/2023] Open
Abstract
Screening of herbal remedies for Cl(-) channel inhibition identified Krisanaklan, a herbal extract used in Thailand for treatment of diarrhea, as an effective antidiarrheal in mouse models of secretory diarrheas with inhibition activity against three Cl(-) channel targets. Krisanaklan fully inhibited cholera toxin-induced intestinal fluid secretion in a closed-loop mouse model with ∼50% inhibition at a 1 ∶ 50 dilution of the extract. Orally administered Krisanaklan (5 µL/g) prevented rotavirus-induced diarrhea in neonatal mice. Short-circuit current measurements showed full inhibition of cAMP and Ca(2+) agonist-induced Cl(-) conductance in human colonic epithelial T84 cells, with ∼ 50% inhibition at a 1 ∶ 5,000 dilution of the extract. Krisanaklan also strongly inhibited intestinal smooth muscle contraction in an ex vivo preparation. Together with measurements using specific inhibitors, we conclude that the antidiarrheal actions of Krisanaklan include inhibition of luminal CFTR and Ca(2+)-activated Cl(-) channels in enterocytes. HPLC fractionation indicated that the three Cl(-) inhibition actions of Krisanaklan are produced by different components in the herbal extract. Testing of individual herbs comprising Krisanaklan indicated that agarwood and clove extracts as primarily responsible for Cl(-) channel inhibition. The low cost, broad antidiarrheal efficacy, and defined cellular mechanisms of Krisanaklan suggests its potential application for antisecretory therapy of cholera and other enterotoxin-mediated secretory diarrheas in developing countries.
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Affiliation(s)
- Lukmanee Tradtrantip
- Departments of Medicine and Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Eun-A Ko
- Departments of Medicine and Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Alan S. Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
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Abstract
Integrin α1β1 is widely expressed in mesenchyme and the immune system, as well as a minority of epithelial tissues. Signaling through α1 contributes to the regulation of extracellular matrix composition, in addition to supplying in some tissues a proliferative and survival signal that appears to be unique among the collagen binding integrins. α1 provides a tissue retention function for cells of the immune system including monocytes and T cells, where it also contributes to their long-term survival, providing for peripheral T cell memory, and contributing to diseases of autoimmunity. The viability of α1 null mice, as well as the generation of therapeutic monoclonal antibodies against this molecule, have enabled studies of the role of α1 in a wide range of pathophysiological circumstances. The immune functions of α1 make it a rational therapeutic target.
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Ball JM, Schroeder ME, Williams CV, Schroeder F, Parr RD. Mutational analysis of the rotavirus NSP4 enterotoxic domain that binds to caveolin-1. Virol J 2013; 10:336. [PMID: 24220211 PMCID: PMC3924327 DOI: 10.1186/1743-422x-10-336] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 10/22/2013] [Indexed: 01/11/2023] Open
Abstract
Background Rotavirus (RV) nonstructural protein 4 (NSP4) is the first described viral enterotoxin, which induces early secretory diarrhea in neonatal rodents. Our previous data show a direct interaction between RV NSP4 and the structural protein of caveolae, caveolin-1 (cav-1), in yeast and mammalian cells. The binding site of cav-1 mapped to the NSP4 amphipathic helix, and led us to examine which helical face was responsible for the interaction. Methods A panel of NSP4 mutants were prepared and tested for binding to cav-1 by yeast two hybrid and direct binding assays. The charged residues of the NSP4 amphipathic helix were changed to alanine (NSP446-175-ala6); and three residues in the hydrophobic face were altered to charged amino acids (NSP446-175-HydroMut). In total, twelve mutants of NSP4 were generated to define the cav-1 binding site. Synthetic peptides corresponding to the hydrophobic and charged faces of NSP4 were examined for structural changes by circular dichroism (CD) and diarrhea induction by a neonatal mouse study. Results Mutations of the hydrophilic face (NSP446-175-Ala6) bound cav-1 akin to wild type NSP4. In contrast, disruption of the hydrophobic face (NSP446-175-HydroMut) failed to bind cav-1. These data suggest NSP4 and cav-1 associate via a hydrophobic interaction. Analyses of mutant synthetic peptides in which the hydrophobic residues in the enterotoxic domain of NSP4 were altered suggested a critical hydrophobic residue. Both NSP4HydroMut112-140, that contains three charged amino acids (aa113, 124, 131) changed from the original hydrophobic residues and NSP4AlaAcidic112-140 that contained three alanine residues substituted for negatively charged (aa114, 125, 132) amino acids failed to induce diarrhea. Whereas peptides NSP4wild type 112−140 and NSP4AlaBasic112-140 that contained three alanine substituted for positively charged (aa115, 119, 133) amino acids, induced diarrhea. Conclusions These data show that the cav-1 binding domain is within the hydrophobic face of the NSP4 amphipathic helix. The integrity of the helical structure is important for both cav-1 binding and diarrhea induction implying a connection between NSP4 functional and binding activities.
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Affiliation(s)
- Judith M Ball
- Department of Pathobiology, Texas A&M University, TVMC, College Station, Texas 77843-4467, USA.
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Rusnati M, Chiodelli P, Bugatti A, Urbinati C. Bridging the past and the future of virology: surface plasmon resonance as a powerful tool to investigate virus/host interactions. Crit Rev Microbiol 2013; 41:238-60. [PMID: 24059853 DOI: 10.3109/1040841x.2013.826177] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Despite decades of antiviral drug research and development, viruses still remain a top global healthcare problem. Compared to eukaryotic cells, viruses are composed by a limited numbers of proteins that, nevertheless, set up multiple interactions with cellular components, allowing the virus to take control of the infected cell. Each virus/host interaction can be considered as a therapeutical target for new antiviral drugs but, unfortunately, the systematic study of a so huge number of interactions is time-consuming and expensive, calling for models overcoming these drawbacks. Surface plasmon resonance (SPR) is a label-free optical technique to study biomolecular interactions in real time by detecting reflected light from a prism-gold film interface. Launched 20 years ago, SPR has become a nearly irreplaceable technology for the study of biomolecular interactions. Accordingly, SPR is increasingly used in the field of virology, spanning from the study of biological interactions to the identification of putative antiviral drugs. From the literature available, SPR emerges as an ideal link between conventional biological experimentation and system biology studies functional to the identification of highly connected viral or host proteins that act as nodal points in virus life cycle and thus considerable as therapeutical targets for the development of innovative antiviral strategies.
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Affiliation(s)
- Marco Rusnati
- Department of Molecular and Translational Medicine, University of Brescia , Brescia , Italy
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Rotavirus NSP4 Triggers Secretion of Proinflammatory Cytokines from Macrophages via Toll-Like Receptor 2. J Virol 2013; 87:11160-7. [PMID: 23926349 DOI: 10.1128/jvi.03099-12] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Nonstructural protein 4 (NSP4), encoded by rotavirus, exhibits various properties linked to viral pathogenesis, including enterotoxic activity. A recent study (O. V. Kavanagh et al., Vaccine 28:3106-3111, 2010) indicated that NSP4 also has adjuvant properties, suggesting a possible role in the innate immune response to rotavirus infection. We report here that NSP4 purified from the medium of rotavirus-infected Caco-2 cells triggers the secretion of proinflammatory cytokines from macrophage-like THP-1 cells and nitric oxide from murine RAW 264.7 cells. Secretion is accompanied by the stimulation of p38 and JNK mitogen-activated protein kinases (MAPKs) and nuclear factor NF-κB. NSP4 triggered the secretion of cytokines from murine macrophages derived from wild-type but not MyD88(-/-) or Toll-like receptor 2 (TLR2(-/-)) mice and induced secretion of interleukin-8 (IL-8) from human embryonic kidney cells transfected with TLR2 but not TLR4. Our studies identify NSP4 as a pathogen-associated molecular pattern (PAMP) encoded by rotavirus and provide a mechanism for the production of proinflammatory cytokines associated with the clinical symptoms of infection in humans and animals.
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Rotavirus replication in the cholangiocyte mediates the temporal dependence of murine biliary atresia. PLoS One 2013; 8:e69069. [PMID: 23844248 PMCID: PMC3700947 DOI: 10.1371/journal.pone.0069069] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 06/05/2013] [Indexed: 01/15/2023] Open
Abstract
Biliary atresia (BA) is a neonatal disease that results in obliteration of the biliary tree. The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy. The purpose of this study was to characterize the temporal relationship between viral infection and the induction of this model. BALB/c mice were infected with RRV on day of life (DOL) 0, 3, 5, and 7. Groups were characterized as early-infection (infection by DOL 3) or late-infection (infection after DOL 5). Early RRV infection induced symptoms in 95% of pups with a mortality rate of 80%. In contrast, late infection caused symptoms in only 50% of mice, and 100% of pups survived. The clinical findings correlated with histological analysis of extrahepatic biliary trees, cytokine expression, and viral titers. Primary murine cholangiocytes isolated, cultured, and infected with RRV yielded higher titers of infectious virus in those harvested from DOL 2 versus DOL 9 mice. Less interferon alpha and beta was produced in DOL 2 versus DOL 9 RRV infected primary cholangiocytes. Injection of BALB/c interferon alpha/beta receptor knockout (IFN-αβR(-/-)) pups at DOL 7 showed increased symptoms (79%) and mortality (46%) when compared to late infected wild type mice. In conclusion, the degree of injury sustained by relatively immature cholangiocytes due to more robust RRV replication correlated with more severe clinical manifestations of cholangiopathy and higher mortality. Interferon alpha production by cholangiocytes appears to play a regulatory role. These findings confirm a temporal dependence of RRV infection in murine BA and begin to define a pathophysiologic role of the maturing cholangiocyte.
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Tange S, Zhou Y, Nagakui-Noguchi Y, Imai T, Nakanishi A. Initiation of human astrovirus type 1 infection was blocked by inhibitors of phosphoinositide 3-kinase. Virol J 2013; 10:153. [PMID: 23680019 PMCID: PMC3750554 DOI: 10.1186/1743-422x-10-153] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 04/23/2013] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Upon initial contact with a virus, host cells activate a series of cellular signaling cascades that facilitate viral entry and viral propagation within the cell. Little is known about how the human astrovirus (HAstV) exploits signaling cascades to establish an infection in host cells. Recent studies showed that activation of extracellular signal-regulated kinase 1/2 (ERK1/2) is important for HAstV infection, though the involvement of other signaling cascades remains unclear. METHODS A panel of kinase blockers was used to search for cellular signaling pathways important for HAstV1 infection. To determine their impact on the infectious process, we examined viral gene expression, RNA replication, and viral RNA and capsid protein release from host cells. RESULTS Inhibitors of phosphoinositide 3-kinase (PI3K) activation interfered with the infection, independent of their effect on ERK 1/2 activation. Activation of the PI3K signaling cascade occurred at an early phase of the infection, judging from the timeframe of Akt phosphorylation. PI3K inhibition at early times, but not at later times, blocked viral gene expression. However, inhibiting the downstream targets of PI3K activation, Akt and Rac1, did not block infection. Inhibition of protein kinase A (PKA) activation was found to block a later phase of HAstV1 production. CONCLUSIONS Our results reveal a previously unknown, essential role of PI3K in the life cycle of HAstV1. PI3K participates in the early stage of infection, possibly during the viral entry process. Our results also reveal the role of PKA in viral production.
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Affiliation(s)
- Shoichiro Tange
- Section of Gene Therapy, Department of Aging Intervention, National Center for Geriatrics and Gerontology, 35, Gengo, Morioka, Obu, Aichi 474-8522, Japan
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González-Ochoa G, Menchaca GE, Hernández CE, Rodríguez C, Tamez RS, Contreras JF. Mutation distribution in the NSP4 protein in rotaviruses isolated from Mexican children with moderate to severe gastroenteritis. Viruses 2013; 5:792-805. [PMID: 23478638 PMCID: PMC3705296 DOI: 10.3390/v5030792] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 01/08/2023] Open
Abstract
The NSP4 protein is a multifunctional protein that plays a role in the morphogenesis and pathogenesis of the rotavirus. Although NSP4 is considered an enterotoxin, the relationship between gastroenteritis severity and amino acid variations in NSP4 of the human rotavirus remains unclear. In this study, we analyzed the sequence diversity of NSP4 and the severity of gastroenteritis of children with moderate to severe gastroenteritis. The rotavirus-infected children were hospitalized before the rotavirus vaccine program in Mexico. All children had diarrhea within 1-4 days, 44 (88%) were vomiting and 35 (70%) had fevers. The severity analysis showed that 13 (26%) cases had mild gastroenteritis, 23 (46%) moderate gastroenteritis and 14 (28%) severe. NSP4 phylogenetic analysis showed three clusters within the genotype E1. Sequence analysis revealed similar mutations inside each cluster, and an uncommon variation in residue 144 was found in five of the Mexican NSP4 sequences. Most of the amino acid variations were located in the VP4 and VP6 binding site domains, with no relationship to different grades of gastroenteritis. This finding indicates that severe gastroenteritis caused by the rotavirus appears to be related to diverse viral or cellular factors instead of NSP4 activity as a unique pathogenic factor.
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Affiliation(s)
- Guadalupe González-Ochoa
- Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, CP. 66451, Mexico.
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35
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Chacko AR, Zwart PH, Read RJ, Dodson EJ, Rao CD, Suguna K. Severe diffraction anisotropy, rotational pseudosymmetry and twinning complicate the refinement of a pentameric coiled-coil structure of NSP4 of rotavirus. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:1541-8. [DOI: 10.1107/s090744491203836x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Accepted: 09/07/2012] [Indexed: 11/10/2022]
Abstract
The crystal structure of the region spanning residues 95–146 of the rotavirus nonstructural protein NSP4 from the asymptomatic human strain ST3 was determined at a resolution of 2.5 Å. Severe diffraction anisotropy, rotational pseudosymmetry and twinning complicated the refinement of this structure. A systematic explanation confirming the crystal pathologies and describing how the structure was successfully refined is given in this report.
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36
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Zambrano JL, Sorondo O, Alcala A, Vizzi E, Diaz Y, Ruiz MC, Michelangeli F, Liprandi F, Ludert JE. Rotavirus infection of cells in culture induces activation of RhoA and changes in the actin and tubulin cytoskeleton. PLoS One 2012; 7:e47612. [PMID: 23082182 PMCID: PMC3474729 DOI: 10.1371/journal.pone.0047612] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 09/19/2012] [Indexed: 12/20/2022] Open
Abstract
Rotavirus infection induces an increase in [Ca2+]cyto, which in turn may affect the distribution of the cytoskeleton proteins in the infected cell. Changes in microfilaments, including the formation of stress fibers, were observed starting at 0.5 h.p.i. using fluorescent phalloidin. Western blot analysis indicated that RhoA is activated between 0.5 and 1 h.p.i. Neither the phosphorylation of RhoA nor the formation of stress fibers were observed in cells infected with virions pre-treated with an anti-VP5* non-neutralizing mAb, suggesting that RhoA activation is stimulated by the interaction of the virus with integrins forming the cell receptor complex. In addition, the structure of the tubulin cytoskeleton was also studied. Alterations of the microtubules were evident starting at 3 h.p.i. and by 7 h.p.i. when microtubules were markedly displaced toward the periphery of the cell cytoplasm. Loading of rotavirus-infected cells with either a Ca2+ chelator (BAPTA) or transfection with siRNAs to silence NSP4, reversed the changes observed in both the microfilaments and microtubules distribution, but not the appearance of stress fibers. These results indicate that alterations in the distribution of actin microfilaments are initiated early during infection by the activation of RhoA, and that latter changes in the Ca2+ homeostasis promoted by NSP4 during infection may be responsible for other alterations in the actin and tubulin cytoskeleton.
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Affiliation(s)
- Jose Luis Zambrano
- Instituto Venezolano de Investigaciones Científicas (IVIC), CMBC. Caracas, Venezuela
- * E-mail: (JLZ); (JL)
| | - Orlando Sorondo
- Instituto Venezolano de Investigaciones Científicas (IVIC), CMBC. Caracas, Venezuela
- Escuela de Biología, Universidad Central de Venezuela (UCV), Caracas, Venezuela
| | - Ana Alcala
- Instituto Venezolano de Investigaciones Científicas (IVIC), CMBC. Caracas, Venezuela
| | - Esmeralda Vizzi
- Instituto Venezolano de Investigaciones Científicas (IVIC), CMBC. Caracas, Venezuela
| | - Yuleima Diaz
- University of Bergen Thormøhlensgate 55, Bergen, Norway
| | - Marie Christine Ruiz
- Instituto Venezolano de Investigaciones Científicas (IVIC), CBB. Caracas, Venezuela
| | - Fabian Michelangeli
- Instituto Venezolano de Investigaciones Científicas (IVIC), CBB. Caracas, Venezuela
| | - Ferdinando Liprandi
- Instituto Venezolano de Investigaciones Científicas (IVIC), CMBC. Caracas, Venezuela
| | - Juan E. Ludert
- Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Ciudad de México, México
- * E-mail: (JLZ); (JL)
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Hu L, Crawford SE, Hyser JM, Estes MK, Prasad BVV. Rotavirus non-structural proteins: structure and function. Curr Opin Virol 2012; 2:380-8. [PMID: 22789743 DOI: 10.1016/j.coviro.2012.06.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 06/13/2012] [Accepted: 06/13/2012] [Indexed: 10/28/2022]
Abstract
The replication of rotavirus is a complex process that is orchestrated by an exquisite interplay between the rotavirus non-structural and structural proteins. Subsequent to particle entry and genome transcription, the non-structural proteins coordinate and regulate viral mRNA translation and the formation of electron-dense viroplasms that serve as exclusive compartments for genome replication, genome encapsidation and capsid assembly. In addition, non-structural proteins are involved in antagonizing the antiviral host response and in subverting important cellular processes to enable successful virus replication. Although far from complete, new structural studies, together with functional studies, provide substantial insight into how the non-structural proteins coordinate rotavirus replication. This brief review highlights our current knowledge of the structure-function relationships of the rotavirus non-structural proteins, as well as fascinating questions that remain to be understood.
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Affiliation(s)
- Liya Hu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, United States
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Dissecting the Ca²⁺ entry pathways induced by rotavirus infection and NSP4-EGFP expression in Cos-7 cells. Virus Res 2012; 167:285-96. [PMID: 22634036 DOI: 10.1016/j.virusres.2012.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/13/2012] [Accepted: 05/16/2012] [Indexed: 01/09/2023]
Abstract
Rotavirus infection modifies Ca(2+) homeostasis provoking an increase in Ca(2+) permeation, cytoplasmic Ca(2+) concentration ([Ca(2+)](cyto)), total Ca(2+) pools and, a decrease of Ca(2+) response to agonists. These effects are mediated by NSP4. The mechanism by which NSP4 deranges Ca(2+) homeostasis is not yet known. It has been proposed that the increase in [Ca(2+)](cyto) is the result of Ca(2+) release from intracellular stores, thereby activating store-operated Ca(2+) entry (SOCE). We studied the mechanisms involved in the changes of Ca(2+) permeability of the plasma membrane elicited by rotavirus infection and NSP4 expression in Cos-7 cells loaded with fura-2 or fluo-4, using inhibitors and activators of different pathways. Total depletion of ER Ca(2+) stores induced by thapsigargin or ATP was not able to elicit Ca(2+) entry in mock-infected cells to the level attained with infection or NSP4-EGFP expression. The pathway induced by NSP4-EGFP expression or infection shows properties shared by SOCE: it can be inactivated by high [Ca(2+)](cyto), is permeable to Mn(2+) and inhibited by La(3+) and the SOC inhibitor 2-aminoethoxydiphenyl borate (2-APB). Contribution of the agonist-operated channels (AOCs) to Ca(2+) entry is small and not modified by infection. The plasma membrane permeability to Ca(2+) in rotavirus infected or NSP4-EGFP expressing cells is also blocked by KB-R7943, an inhibitor of the plasma membrane Na(+)/Ca(2+) exchanger (NCX), operating in its reverse mode. In conclusion, the expression of NSP4 in infected Cos-7 cells appears to activate the NCX in reverse mode and the SOCE pathway to induce increased Ca(2+) entry.
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Elucidation of the Rotavirus NSP4-Caveolin-1 and -Cholesterol Interactions Using Synthetic Peptides. JOURNAL OF AMINO ACIDS 2012; 2012:575180. [PMID: 22500212 PMCID: PMC3303745 DOI: 10.1155/2012/575180] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 11/16/2011] [Indexed: 01/19/2023]
Abstract
Rotavirus (RV) NSP4, the first described viral enterotoxin, is a multifunctional glycoprotein that contributes to viral pathogenesis, morphogenesis, and replication. NSP4 binds both termini of caveolin-1 and is isolated from caveolae fractions that are rich in anionic phospholipids and cholesterol. These interactions indicate that cholesterol/caveolin-1 plays a role in NSP4 transport to the cell surface, which is essential to its enterotoxic activity. Synthetic peptides were utilized to identify target(s) of intervention by exploring the NSP4-caveolin-1 and -cholesterol interactions. NSP4112–140 that overlaps the caveolin-1 binding domain and a cholesterol recognition amino acid consensus (CRAC) motif and both termini of caveolin-1 (N-caveolin-12–20, 19–40 and C-caveolin-1161–180) were synthesized. Direct fluorescence-binding assays were employed to determine binding affinities of the NSP4-caveolin-1 peptides and cholesterol. Intracellular cholesterol alteration revealed a redistribution of NSP4 and disintegration of viroplasms. These data further imply interruption of NSP4112–140-N-caveolin-119–40 and cholesterol interactions may block NSP4 intracellular transport, hence enterotoxicity.
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Didsbury A, Wang C, Verdon D, Sewell MA, McIntosh JD, Taylor JA. Rotavirus NSP4 is secreted from infected cells as an oligomeric lipoprotein and binds to glycosaminoglycans on the surface of non-infected cells. Virol J 2011; 8:551. [PMID: 22185400 PMCID: PMC3305486 DOI: 10.1186/1743-422x-8-551] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/20/2011] [Indexed: 12/22/2022] Open
Abstract
Background Nonstructural glycoprotein 4 (NSP4) encoded by rotavirus is the only viral protein currently believed to function as an enterotoxin. NSP4 is synthesized as an intracellular transmembrane glycoprotein and as such is essential for virus assembly. Infection of polarized Caco-2 cells with rotavirus also results in the secretion of glycosylated NSP4 apparently in a soluble form despite retention of its transmembrane domain. We have examined the structure, solubility and cell-binding properties of this secreted form of NSP4 to further understand the biochemical basis for its enterotoxic function. We show here that NSP4 is secreted as discrete detergent-sensitive oligomers in a complex with phospholipids and demonstrate that this secreted form of NSP4 can bind to glycosaminoglycans present on the surface of a range of different cell types. Methods NSP4 was purified from the medium of infected cells after ultracentrifugation and ultrafiltration by successive lectin-affinity and ion exchange chromatography. Oligomerisation of NSP4 was examined by density gradient centrifugation and chemical crosslinking and the lipid content was assessed by analytical thin layer chromatography and flame ionization detection. Binding of NSP4 to various cell lines was measured using a flow cytometric-based assay. Results Secreted NSP4 formed oligomers that contained phospholipid but dissociated to a dimeric species in the presence of non-ionic detergent. The purified glycoprotein binds to the surface of various non-infected cells of distinct lineage. Binding of NSP4 to HT-29, a cell line of intestinal origin, is saturable and independent of divalent cations. Complementary biochemical approaches reveal that NSP4 binds to sulfated glycosaminoglycans on the plasma membrane. Conclusion Our study is the first to analyze an authentic (i.e. non-recombinant) form of NSP4 that is secreted from virus-infected cells. Despite retention of the transmembrane domain, secreted NSP4 remains soluble in an aqueous environment as an oligomeric lipoprotein that can bind to various cell types via an interaction with glycosaminoglycans. This broad cellular tropism exhibited by NSP4 may have implications for the pathophysiology of rotavirus disease.
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Affiliation(s)
- Alicia Didsbury
- School of Biological Sciences, University of Auckland, New Zealand
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41
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Chacko AR, Jeyakanthan J, Ueno G, Sekar K, Rao CD, Dodson EJ, Suguna K, Read RJ. A new pentameric structure of rotavirus NSP4 revealed by molecular replacement. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2011; 68:57-61. [DOI: 10.1107/s0907444911049705] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Accepted: 11/21/2011] [Indexed: 11/10/2022]
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Yang W, McCrae MA. The molecular biology of rotaviruses X: intercellular dissemination of rotavirus NSP4 requires glycosylation and is mediated by direct cell-cell contact through cytoplasmic extrusions. Arch Virol 2011; 157:305-14. [DOI: 10.1007/s00705-011-1174-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 11/08/2011] [Indexed: 01/11/2023]
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Sastri NP, Pamidimukkala K, Marathahalli JR, Kaza S, Rao CD. Conformational Differences Unfold a Wide Range of Enterotoxigenic Abilities Exhibited by rNSP4 Peptides from Different Rotavirus Strains. Open Virol J 2011; 5:124-35. [PMID: 22253650 PMCID: PMC3256577 DOI: 10.2174/1874357901105010124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 08/18/2011] [Accepted: 09/06/2011] [Indexed: 12/28/2022] Open
Abstract
NSP4 has been recognized as the rotavirus-encoded enterotoxin. However, a few studies failed to support its diarrheagenic activity. As recombinant NSP4 (rNSP4) peptides of different lengths were used in the limited number of studies, a comparison of relative diarrheagenic potential of NSP4 from different strains could not be possible. To better understand the diarrheagenic potential of NSP4 from different strains, in this report we have evaluated the enterotoxigenic activity of the deletion mutant ΔN72 that lacks the N-terminal 72 residues and the biologically relevant ΔN112 peptide which when derived from SA11 rotavirus strain were previously shown to be highly diarrheagenic in newborn mice. Detailed comparative analysis of biochemical and biophysical properties and diarrheagenic activity of the recombinant ΔN72 peptides from seventeen different strains under identical conditions revealed wide differences among themselves in their resistance to trypsin cleavage, thioflavin T (ThT) binding, multimerization and conformation without any correlation with their diarrhea inducing abilities. These results support our previously proposed concept for the requirement of a unique conformation for optimal biological functions conferred by cooperation between the N- and C-terminal regions of the cytoplasmic tail.
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Novel pentameric structure of the diarrhea-inducing region of the rotavirus enterotoxigenic protein NSP4. J Virol 2011; 85:12721-32. [PMID: 21917949 DOI: 10.1128/jvi.00349-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A novel pentameric structure which differs from the previously reported tetrameric form of the diarrhea-inducing region of the rotavirus enterotoxin NSP4 is reported here. A significant feature of this pentameric form is the absence of the calcium ion located in the core region of the tetrameric structures. The lysis of cells, the crystallization of the region spanning residues 95 to 146 of NSP4 (NSP4(95-146)) of strain ST3 (ST3:NSP4(95-146)) at acidic pH, and comparative studies of the recombinant purified peptide under different conditions by size-exclusion chromatography (SEC) and of the crystal structures suggested pH-, Ca(2+)-, and protein concentration-dependent oligomeric transitions in the peptide. Since the NSP4(95-146) mutant lacks the N-terminal amphipathic domain (AD) and most of the C-terminal flexible region (FR), to demonstrate that the pentameric transition is not a consequence of the lack of the N- and C-terminal regions, glutaraldehyde cross-linking of the ΔN72 and ΔN94 mutant proteins, which contain or lack the AD, respectively, but possess the complete C-terminal FR, was carried out. The results indicate the presence of pentamers in preparations of these longer mutants. Detailed SEC analyses of ΔN94 prepared under different conditions, however, revealed protein concentration-dependent but metal ion- and pH-independent pentamer accumulation at high concentrations which dissociated into tetramers and lower oligomers at low protein concentrations. While calcium appeared to stabilize the tetramer, magnesium in particular stabilized the dimer. ΔN72 existed primarily in the multimeric form under all conditions. These findings of a calcium-free NSP4 pentamer and its concentration-dependent and largely calcium-independent oligomeric transitions open up a new dimension in an understanding of the structural basis of its multitude of functions.
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Hagbom M, Istrate C, Engblom D, Karlsson T, Rodriguez-Diaz J, Buesa J, Taylor JA, Loitto VM, Magnusson KE, Ahlman H, Lundgren O, Svensson L. Rotavirus stimulates release of serotonin (5-HT) from human enterochromaffin cells and activates brain structures involved in nausea and vomiting. PLoS Pathog 2011; 7:e1002115. [PMID: 21779163 PMCID: PMC3136449 DOI: 10.1371/journal.ppat.1002115] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 04/26/2011] [Indexed: 11/18/2022] Open
Abstract
Rotavirus (RV) is the major cause of severe gastroenteritis in young children. A virus-encoded enterotoxin, NSP4 is proposed to play a major role in causing RV diarrhoea but how RV can induce emesis, a hallmark of the illness, remains unresolved. In this study we have addressed the hypothesis that RV-induced secretion of serotonin (5-hydroxytryptamine, 5-HT) by enterochromaffin (EC) cells plays a key role in the emetic reflex during RV infection resulting in activation of vagal afferent nerves connected to nucleus of the solitary tract (NTS) and area postrema in the brain stem, structures associated with nausea and vomiting. Our experiments revealed that RV can infect and replicate in human EC tumor cells ex vivo and in vitro and are localized to both EC cells and infected enterocytes in the close vicinity of EC cells in the jejunum of infected mice. Purified NSP4, but not purified virus particles, evoked release of 5-HT within 60 minutes and increased the intracellular Ca2+ concentration in a human midgut carcinoid EC cell line (GOT1) and ex vivo in human primary carcinoid EC cells concomitant with the release of 5-HT. Furthermore, NSP4 stimulated a modest production of inositol 1,4,5-triphosphate (IP3), but not of cAMP. RV infection in mice induced Fos expression in the NTS, as seen in animals which vomit after administration of chemotherapeutic drugs. The demonstration that RV can stimulate EC cells leads us to propose that RV disease includes participation of 5-HT, EC cells, the enteric nervous system and activation of vagal afferent nerves to brain structures associated with nausea and vomiting. This hypothesis is supported by treating vomiting in children with acute gastroenteritis with 5-HT3 receptor antagonists. Rotavirus (RV) can cause severe dehydration and is a leading cause of childhood deaths worldwide. While most deaths occur due to excessive loss of fluids and electrolytes through vomiting and diarrhoea, the pathophysiological mechanisms that underlie this life-threatening disease remain to be clarified. Our previous studies revealed that drugs that inhibit the function of the enteric nervous system can reduce symptoms of RV disease in mice. In this study we have addressed the hypothesis that RV infection triggers the release of serotonin (5-hydroxytryptamine, 5-HT) from enterochromaffin (EC) cells in the intestine leading to activation of vagal afferent nerves connected to brain stem structures associated with vomiting. RV activated Fos expression in the nucleus of the solitary tract of CNS, the main target for incoming fibers from the vagal nerve. Both secreted and recombinant forms of the viral enterotoxin (NSP4), increased intracellular Ca2+ concentration and released 5-HT from EC cells. 5-HT induced diarrhoea in mice within 60 min, thereby supporting the role of 5-HT in RV disease. Our study provides novel insight into the complex interaction between RV, EC cells, 5-HT and nerves.
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Affiliation(s)
- Marie Hagbom
- Division of Molecular Virology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Claudia Istrate
- Division of Molecular Virology, Medical Faculty, University of Linköping, Linköping, Sweden
- Unidade de Biologia Molecular, Centro de Malaria e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal
| | - David Engblom
- Division of Cell Biology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Thommie Karlsson
- Division of Medical Microbiology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Jesus Rodriguez-Diaz
- Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain
| | - Javier Buesa
- Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain
| | - John A. Taylor
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Vesa-Matti Loitto
- Division of Medical Microbiology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Karl-Eric Magnusson
- Division of Medical Microbiology, Medical Faculty, University of Linköping, Linköping, Sweden
| | - Håkan Ahlman
- Department of Surgery, University of Gothenburg, Gothenburg, Sweden
| | - Ove Lundgren
- Department of Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Lennart Svensson
- Division of Molecular Virology, Medical Faculty, University of Linköping, Linköping, Sweden
- * E-mail:
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Gibbons TF, Storey SM, Williams CV, McIntosh A, Mitchel DM, Parr RD, Schroeder ME, Schroeder F, Ball JM. Rotavirus NSP4: Cell type-dependent transport kinetics to the exofacial plasma membrane and release from intact infected cells. Virol J 2011; 8:278. [PMID: 21645398 PMCID: PMC3129587 DOI: 10.1186/1743-422x-8-278] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 06/06/2011] [Indexed: 11/10/2022] Open
Abstract
Background Rotavirus NSP4 localizes to multiple intracellular sites and is multifunctional, contributing to RV morphogenesis, replication and pathogenesis. One function of NSP4 is the induction of early secretory diarrhea by binding surface receptors to initiate signaling events. The aims of this study were to determine the transport kinetics of NSP4 to the exofacial plasma membrane (PM), the subsequent release from intact infected cells, and rebinding to naïve and/or neighboring cells in two cell types. Methods Transport kinetics was evaluated using surface-specific biotinylation/streptavidin pull-downs and exofacial exposure of NSP4 was confirmed by antibody binding to intact cells, and fluorescent resonant energy transfer. Transfected cells similarly were monitored to discern NSP4 movement in the absence of infection or other viral proteins. Endoglycosidase H digestions, preparation of CY3- or CY5- labeled F(ab)2 fragments, confocal imaging, and determination of preferential polarized transport employed standard laboratory techniques. Mock-infected, mock-biotinylated and non-specific antibodies served as controls. Results Only full-length (FL), endoglycosidase-sensitive NSP4 was detected on the exofacial surface of two cell types, whereas the corresponding cell lysates showed multiple glycosylated forms. The C-terminus of FL NSP4 was detected on exofacial-membrane surfaces at different times in different cell types prior to its release into culture media. Transport to the PM was rapid and distinct yet FL NSP4 was secreted from both cell types at a time similar to the release of virus. NSP4-containing, clarified media from both cells bound surface molecules of naïve cells, and imaging showed secreted NSP4 from one or more infected cells bound neighboring cell membranes in culture. Preferential sorting to apical or basolateral membranes also was distinct in different polarized cells. Conclusions The intracellular transport of NSP4 to the PM, translocation across the PM, exposure of the C-terminus on the cell surface and subsequent secretion occurs via an unusual, complex and likely cell-dependent process. The exofacial exposure of the C-terminus poses several questions and suggests an atypical mechanism by which NSP4 traverses the PM and interacts with membrane lipids. Mechanistic details of the unconventional trafficking of NSP4, interactions with host-cell specific molecules and subsequent release require additional study.
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Affiliation(s)
- Thomas F Gibbons
- Department of Pathobiology Texas A&M University, TVMC, College Station, TX 77843-4467, USA
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Mekahli D, Bultynck G, Parys JB, De Smedt H, Missiaen L. Endoplasmic-reticulum calcium depletion and disease. Cold Spring Harb Perspect Biol 2011; 3:a004317. [PMID: 21441595 PMCID: PMC3098671 DOI: 10.1101/cshperspect.a004317] [Citation(s) in RCA: 329] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The endoplasmic reticulum (ER) as an intracellular Ca(2+) store not only sets up cytosolic Ca(2+) signals, but, among other functions, also assembles and folds newly synthesized proteins. Alterations in ER homeostasis, including severe Ca(2+) depletion, are an upstream event in the pathophysiology of many diseases. On the one hand, insufficient release of activator Ca(2+) may no longer sustain essential cell functions. On the other hand, loss of luminal Ca(2+) causes ER stress and activates an unfolded protein response, which, depending on the duration and severity of the stress, can reestablish normal ER function or lead to cell death. We will review these various diseases by mainly focusing on the mechanisms that cause ER Ca(2+) depletion.
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Affiliation(s)
- Djalila Mekahli
- Laboratory of Molecular and Cellular Signaling, Department of Molecular Cell Biology, KU Leuven Campus Gasthuisberg O&N I, Belgium
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Fleming FE, Graham KL, Takada Y, Coulson BS. Determinants of the specificity of rotavirus interactions with the alpha2beta1 integrin. J Biol Chem 2010; 286:6165-74. [PMID: 21138834 DOI: 10.1074/jbc.m110.142992] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The human α2β1 integrin binds collagen and acts as a cellular receptor for rotaviruses and human echovirus 1. These ligands require the inserted (I) domain within the α2 subunit of α2β1 for binding. Previous studies have identified the binding sites for collagen and echovirus 1 in the α2 I domain. We used CHO cells expressing mutated α2β1 to identify amino acids involved in binding to human and animal rotaviruses. Residues where mutation affected rotavirus binding were located in several exposed loops and adjacent regions of the α2 I domain. Binding by all rotaviruses was eliminated by mutations in the activation-responsive αC-α6 and αF helices. This is a novel feature that distinguishes rotavirus from other α2β1 ligands. Mutation of residues that co-ordinate the metal ion (Ser-153, Thr-221, and Glu-256 in α2 and Asp-130 in β1) and nearby amino acids (Ser-154, Gln-215, and Asp-219) also inhibited rotavirus binding. The importance of most of these residues was greatest for binding by human rotaviruses. These mutations inhibit collagen binding to α2β1 (apart from Glu-256) but do not affect echovirus binding. Overall, residues where mutation affected both rotavirus and collagen recognition are located at one side of the metal ion-dependent adhesion site, whereas those important for collagen alone cluster nearby. Mutations eliminating rotavirus and echovirus binding are distinct, consistent with the respective preference of these viruses for activated or inactive α2β1. In contrast, rotavirus and collagen utilize activated α2β1 and show an overlap in α2β1 residues important for binding.
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Affiliation(s)
- Fiona E Fleming
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria 3010, Australia
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Deal EM, Jaimes MC, Crawford SE, Estes MK, Greenberg HB. Rotavirus structural proteins and dsRNA are required for the human primary plasmacytoid dendritic cell IFNalpha response. PLoS Pathog 2010; 6:e1000931. [PMID: 20532161 PMCID: PMC2880586 DOI: 10.1371/journal.ppat.1000931] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Accepted: 04/28/2010] [Indexed: 12/29/2022] Open
Abstract
Rotaviruses are the leading cause of severe dehydrating diarrhea in children worldwide. Rotavirus-induced immune responses, especially the T and B cell responses, have been extensively characterized; however, little is known about innate immune mechanisms involved in the control of rotavirus infection. Although increased levels of systemic type I interferon (IFNalpha and beta) correlate with accelerated resolution of rotavirus disease, multiple rotavirus strains, including rhesus rotavirus (RRV), have been demonstrated to antagonize type I IFN production in a variety of epithelial and fibroblast cell types through several mechanisms, including degradation of multiple interferon regulatory factors by a viral nonstructural protein. This report demonstrates that stimulation of highly purified primary human peripheral plasmacytoid dendritic cells (pDCs) with either live or inactivated RRV induces substantial IFNalpha production by a subset of pDCs in which RRV does not replicate. Characterization of pDC responses to viral stimulus by flow cytometry and Luminex revealed that RRV replicates in a small subset of human primary pDCs and, in this RRV-permissive small subset, IFNalpha production is diminished. pDC activation and maturation were observed independently of viral replication and were enhanced in cells in which virus replicates. Production of IFNalpha by pDCs following RRV exposure required viral dsRNA and surface proteins, but neither viral replication nor activation by trypsin cleavage of VP4. These results demonstrate that a minor subset of purified primary human peripheral pDCs are permissive to RRV infection, and that pDCs retain functionality following RRV stimulus. Additionally, this study demonstrates trypsin-independent infection of primary peripheral cells by rotavirus, which may allow for the establishment of extraintestinal viremia and antigenemia. Importantly, these data provide the first evidence of IFNalpha induction in primary human pDCs by a dsRNA virus, while simultaneously demonstrating impaired IFNalpha production in primary human cells in which RRV replicates. Rotavirus infection of primary human pDCs provides a powerful experimental system for the study of mechanisms underlying pDC-mediated innate immunity to viral infection and reveals a potentially novel dsRNA-dependent pathway of IFNalpha induction.
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Affiliation(s)
- Emily M. Deal
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Maria C. Jaimes
- BD Biosciences, San Jose, California, United States of America
| | - 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
| | - Harry B. Greenberg
- Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America
- Veterans Affairs (VA) Palo Alto Health Care System, Palo Alto, California, United States of America
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Halasz P, Holloway G, Coulson BS. Death mechanisms in epithelial cells following rotavirus infection, exposure to inactivated rotavirus or genome transfection. J Gen Virol 2010; 91:2007-2018. [PMID: 20392902 DOI: 10.1099/vir.0.018275-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Intestinal epithelial cell death following rotavirus infection is associated with villus atrophy and gastroenteritis. Roles for both apoptosis and necrosis in cytocidal activity within rotavirus-infected epithelial cells have been proposed. Additionally, inactivated rotavirus has been reported to induce diarrhoea in infant mice. We further examined the death mechanisms induced in epithelial cell lines following rotavirus infection or inactivated rotavirus exposure. Monolayer integrity changes in MA104, HT-29 and partially differentiated Caco-2 cells following inactivated rotavirus exposure or RRV or CRW-8 rotavirus infection paralleled cell metabolic activity and viability reductions. MA104 cell exposure to rotavirus dsRNA also altered monolayer integrity. Inactivated rotaviruses induced delayed cell function losses that were unrelated to apoptosis. Phosphatidylserine externalization, indicating early apoptosis, occurred in MA104 and HT-29 but not in partially differentiated Caco-2 cells by 11 h after infection. Rotavirus activation of phosphatidylinositol 3-kinase partially protected MA104 and HT-29 cells from early apoptosis. In contrast, activation of the stress-activated protein kinase JNK by rotavirus did not influence apoptosis induction in these cells. RRV infection produced DNA fragmentation, indicating late-stage apoptosis, in fully differentiated Caco-2 cells only. These studies show that the apoptosis initiation and cell death mechanism induced by rotavirus infection depend on cell type and degree of differentiation. Early stage apoptosis resulting from rotavirus infection is probably counter-balanced by virus-induced phosphatidylinositol 3-kinase activation. The ability of inactivated rotaviruses and rotavirus dsRNA to perturb monolayer integrity supports a potential role for these rotavirus components in disease pathogenesis.
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Affiliation(s)
- Peter Halasz
- Department of Microbiology and Immunology, The University of Melbourne, VIC 3010, Australia
| | - Gavan Holloway
- Department of Microbiology and Immunology, The University of Melbourne, VIC 3010, Australia
| | - Barbara S Coulson
- Department of Microbiology and Immunology, The University of Melbourne, VIC 3010, Australia
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