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Chandra P, Patra U, Mukhopadhyay U, Mukherjee A, Halder P, Koley H, Chawla-Sarkar M. Rotavirus non-structural protein 4 usurps host cellular RIPK1-RIPK3 complex to induce MLKL-dependent necroptotic cell death. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119745. [PMID: 38719029 DOI: 10.1016/j.bbamcr.2024.119745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 04/11/2024] [Accepted: 04/16/2024] [Indexed: 05/14/2024]
Abstract
The dynamic interface between invading viral pathogens and programmed cell death (PCD) of the host is a finely regulated process. Host cellular demise at the end of the viral life cycle ensures the release of progeny virions to initiate new infection cycles. Rotavirus (RV), a diarrheagenic virus with double-stranded RNA genome, has been reported to trigger different types of PCD such as apoptosis and pyroptosis in a highly regulated way to successfully disseminate progeny virions. Recently our lab also showed that induction of MLKL-driven programmed necroptosis by RV. However, the host cellular machinery involved in RV-induced necroptosis and the upstream viral trigger responsible for it remained unaddressed. In the present study, the signalling upstream of MLKL-driven necroptosis has been delineated where the involvement of Receptor interacting serine/threonine kinase 3 (RIPK3) and 1 (RIPK1) from the host side and RV non-structural protein 4 (NSP4) as the viral trigger for necroptosis has been shown. Interestingly, RV-NSP4 was found to be an integral component of the necrosome complex by interacting with RIPK1, thereby bypassing the requirement of RIPK1 kinase activity. Subsequently, NSP4-driven elevated cytosolic Ca2+ concentration and Ca2+-binding to NSP4 lead further to RHIM domain-dependent RIPK1-RIPK3 interaction, RIPK3-dependent MLKL phosphorylation, and eventual necroptosis. Overall, this study presents the interplay between RV-NSP4 and the host cellular necrosome complex to induce necroptotic death of host cells.
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Affiliation(s)
- Pritam Chandra
- Division of Virology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India
| | - Upayan Patra
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt, Germany
| | - Urbi Mukhopadhyay
- European Molecular Biology Laboratory, 71 Av. Des Martyrs, 38000 Grenoble, France
| | - Arpita Mukherjee
- Division of Virology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India
| | - Prolay Halder
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India
| | - Hemanta Koley
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India
| | - Mamta Chawla-Sarkar
- Division of Virology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India.
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Gao L, Shen H, Zhao S, Chen S, Zhu P, Lin W, Chen F. Isolation and Pathogenicity Analysis of a G5P[23] Porcine Rotavirus Strain. Viruses 2023; 16:21. [PMID: 38257722 PMCID: PMC10819142 DOI: 10.3390/v16010021] [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: 11/02/2023] [Revised: 12/12/2023] [Accepted: 12/17/2023] [Indexed: 01/24/2024] Open
Abstract
(1) Background: Group A rotaviruses (RVAs) are the primary cause of severe intestinal diseases in piglets. Porcine rotaviruses (PoRVs) are widely prevalent in Chinese farms, resulting in significant economic losses to the livestock industry. However, isolation of PoRVs is challenging, and their pathogenicity in piglets is not well understood. (2) Methods: We conducted clinical testing on a farm in Jiangsu Province, China, and isolated PoRV by continuously passaging on MA104 cells. Subsequently, the pathogenicity of the isolated strain in piglets was investigated. The piglets of the PoRV-infection group were orally inoculated with 1 mL of 1.0 × 106 TCID50 PoRV, whereas those of the mock-infection group were fed with an equivalent amount of DMEM. (3) Results: A G5P[23] genotype PoRV strain was successfully isolated from one of the positive samples and named RVA/Pig/China/JS/2023/G5P[23](JS). The genomic constellation of this strain was G5-P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1. Sequence analysis revealed that the genes VP3, VP7, NSP2, and NSP4 of the JS strain were closely related to human RVAs, whereas the remaining gene segments were closely related to porcine RVAs, indicating a reassortment between porcine and human strains. Furthermore, infection of 15-day-old piglets with the JS strain resulted in a diarrheal rate of 100% (8 of 8) and a mortality rate of 37.5% (3 of 8). (4) Conclusions: The isolated G5P[23] genotype rotavirus strain, which exhibited strong pathogenicity in piglets, may have resulted from recombination between porcine and human strains. It may serve as a potential candidate strain for developing vaccines, and its immunogenicity can be tested in future studies.
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Affiliation(s)
- Liguo Gao
- College of Animal Science, South China Agricultural University, Guangzhou 510642, China; (L.G.); (S.Z.); (S.C.); (P.Z.); (W.L.)
| | - Hanqin Shen
- Wen’s Food Group, Yunfu 527300, China;
- Guangdong Jingjie Inspection and Testing Co., Ltd., Yunfu 527300, China
| | - Sucan Zhao
- College of Animal Science, South China Agricultural University, Guangzhou 510642, China; (L.G.); (S.Z.); (S.C.); (P.Z.); (W.L.)
| | - Sheng Chen
- College of Animal Science, South China Agricultural University, Guangzhou 510642, China; (L.G.); (S.Z.); (S.C.); (P.Z.); (W.L.)
| | - Puduo Zhu
- College of Animal Science, South China Agricultural University, Guangzhou 510642, China; (L.G.); (S.Z.); (S.C.); (P.Z.); (W.L.)
| | - Wencheng Lin
- College of Animal Science, South China Agricultural University, Guangzhou 510642, China; (L.G.); (S.Z.); (S.C.); (P.Z.); (W.L.)
| | - Feng Chen
- College of Animal Science, South China Agricultural University, Guangzhou 510642, China; (L.G.); (S.Z.); (S.C.); (P.Z.); (W.L.)
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Basnet S, Mohanty C, Bochkov YA, Brockman-Schneider RA, Kendziorski C, Gern JE. Rhinovirus C causes heterogeneous infection and gene expression in airway epithelial cell subsets. Mucosal Immunol 2023; 16:386-398. [PMID: 36796588 PMCID: PMC10629931 DOI: 10.1016/j.mucimm.2023.01.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 01/27/2023] [Indexed: 02/16/2023]
Abstract
Rhinoviruses infect ciliated airway epithelial cells, and rhinoviruses' nonstructural proteins quickly inhibit and divert cellular processes for viral replication. However, the epithelium can mount a robust innate antiviral immune response. Therefore, we hypothesized that uninfected cells contribute significantly to the antiviral immune response in the airway epithelium. Using single-cell RNA sequencing, we demonstrate that both infected and uninfected cells upregulate antiviral genes (e.g. MX1, IFIT2, IFIH1, and OAS3) with nearly identical kinetics, whereas uninfected non-ciliated cells are the primary source of proinflammatory chemokines. Furthermore, we identified a subset of highly infectable ciliated epithelial cells with minimal interferon responses and determined that interferon responses originate from distinct subsets of ciliated cells with moderate viral replication. These findings suggest that the composition of ciliated airway epithelial cells and coordinated responses of infected and uninfected cells could determine the risk of more severe viral respiratory illnesses in children with asthma, chronic obstructive pulmonary disease, and genetically susceptible individuals.
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Affiliation(s)
- Sarmila Basnet
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
| | - Chitrasen Mohanty
- Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI, USA
| | - Yury A Bochkov
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | | | - Christina Kendziorski
- Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI, USA
| | - James E Gern
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
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Lee YS, Lee GH, Kwon YS. Update on benign convulsions with mild gastroenteritis. Clin Exp Pediatr 2022; 65:469-475. [PMID: 34961297 PMCID: PMC9561189 DOI: 10.3345/cep.2021.00997] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 12/15/2021] [Indexed: 12/16/2022] Open
Abstract
Benign convulsions with mild gastroenteritis (CwG) are characterized by afebrile convulsions associated with viral gastroenteritis in previously healthy infants and children. The main causative pathogens are rotavirus and norovirus. CwG occurs frequently in both East Asian and Western countries. The prevalence of CwG was reportedly not decreased by the introduction of rotavirus vaccines, and the prevalence of norovirus-associated CwG has been increasing annually. Convulsions in CwG are usually clustered, do not last longer than 5 minutes, and are mostly generalized. Laboratory diagnostics, electroencephalography (EEG), and imaging findings are usually normal. There is a probability of mild, transient abnormal findings on EEG or imaging limited to the acute disease phase. Although several reports have suggested that pathogens that affect the central nervous system through direct or indirect mechanisms could be related to the pathophysiology of CwG, its mechanism is not fully understood. Several antiepileptic drugs are effective during convulsions; however, long-term antiepileptic treatment is not required as CwG usually has a good prognosis.
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Affiliation(s)
- Yeong Seok Lee
- Department of Pediatrics, School of Medicine, Inha University, Incheon, Korea
| | - Ga Hee Lee
- Department of Pediatrics, School of Medicine, Inha University, Incheon, Korea
| | - Young Se Kwon
- Department of Pediatrics, School of Medicine, Inha University, Incheon, Korea
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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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Feng T, Zhang J, Chen Z, Pan W, Chen Z, Yan Y, Dai J. Glycosylation of viral proteins: Implication in virus-host interaction and virulence. Virulence 2022; 13:670-683. [PMID: 35436420 PMCID: PMC9037552 DOI: 10.1080/21505594.2022.2060464] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glycans are among the most important cell molecular components. However, given their structural diversity, their functions have not been fully explored. Glycosylation is a vital post-translational modification for various proteins. Many bacteria and viruses rely on N-linked and O-linked glycosylation to perform critical biological functions. The diverse functions of glycosylation on viral proteins during viral infections, including Dengue, Zika, influenza, and human immunodeficiency viruses as well as coronaviruses have been reported. N-linked glycosylation is the most common form of protein modification, and it modulates folding, transportation and receptor binding. Compared to N-linked glycosylation, the functions of O-linked viral protein glycosylation have not been comprehensively evaluated. In this review, we summarize findings on viral protein glycosylation, with particular attention to studies on N-linked glycosylation in viral life cycles. This review informs the development of virus-specific vaccines or inhibitors.
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Affiliation(s)
- Tingting Feng
- Jiangsu Key Laboratory of Infection and Immunity, Institute of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Jinyu Zhang
- Jiangsu Key Laboratory of Infection and Immunity, Institute of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Zhiqian Chen
- Jiangsu Key Laboratory of Infection and Immunity, Institute of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Wen Pan
- Jiangsu Key Laboratory of Infection and Immunity, Institute of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Zhengrong Chen
- Department of Respiratory Medicine, Children's Hospital of Soochow University, Soochow University, Suzhou, China
| | - Yongdong Yan
- Department of Respiratory Medicine, Children's Hospital of Soochow University, Soochow University, Suzhou, China
| | - Jianfeng Dai
- Jiangsu Key Laboratory of Infection and Immunity, Institute of Biology and Medical Sciences, Soochow University, Suzhou, China
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7
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Lu MC, Lin SC, Hsu YH, Chen SY. Epidemiology, Clinical Features, and Unusual Complications of Norovirus Infection in Taiwan: What We Know after Rotavirus Vaccines. Pathogens 2022; 11:pathogens11040451. [PMID: 35456126 PMCID: PMC9026459 DOI: 10.3390/pathogens11040451] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/01/2022] [Accepted: 04/07/2022] [Indexed: 02/01/2023] Open
Abstract
Noroviruses (NoVs) are one of the emerging and rapidly spreading groups of pathogens threatening human health. A reduction in sporadic NoV infections was noted following the start of the COVID-19 pandemic, but the return of NoV gastroenteritis during the COVID-19 pandemic has been noted recently. Research in recent years has shown that different virus strains are associated with different clinical characteristics; moreover, there is a paucity of research into extraintestinal or unusual complications that may be associated with NoV. The genomic diversity of circulating NoVs is also complex and may vary significantly. Therefore, this short narrative review focuses on sharing the Taiwan experience of NoV infection including epidemiology, clinical features, and complications following suboptimal rotavirus immunization in Taiwan (after October 2006). We also highlight the unusual complications associated with NoV infections and the impacts of NoV infection during the COVID-19 pandemic in the literature for possible future research directions. To conclude, further research is needed to quantify the burden of NoV across the spectrum of disease severity in Taiwan. The evidence of the connection between NoV and the unusual complications is still lacking.
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Affiliation(s)
- Meng-Che Lu
- Division of Allergy, Asthma and Immunology, Department of Pediatrics, Shuang Ho Hospital, Taipei Medical University, New Taipei City 23561, Taiwan; (M.-C.L.); (S.-C.L.)
| | - Sheng-Chieh Lin
- Division of Allergy, Asthma and Immunology, Department of Pediatrics, Shuang Ho Hospital, Taipei Medical University, New Taipei City 23561, Taiwan; (M.-C.L.); (S.-C.L.)
- Department of Pediatrics, School of Medicine, College of Medicine, Taipei Medical University, Taipei city 11031, Taiwan
| | - Yi-Hsiang Hsu
- Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA;
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Shih-Yen Chen
- Department of Pediatrics, School of Medicine, College of Medicine, Taipei Medical University, Taipei city 11031, Taiwan
- Division of Pediatric Gastroenterology and Hepatology, Department of Pediatrics, Shuang Ho Hospital, Taipei Medical University, New Taipei City 23561, Taiwan
- Correspondence:
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Breitinger U, Farag NS, Sticht H, Breitinger HG. Viroporins: Structure, function, and their role in the life cycle of SARS-CoV-2. Int J Biochem Cell Biol 2022; 145:106185. [PMID: 35219876 PMCID: PMC8868010 DOI: 10.1016/j.biocel.2022.106185] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/15/2022] [Accepted: 02/21/2022] [Indexed: 12/12/2022]
Abstract
Viroporins are indispensable for viral replication. As intracellular ion channels they disturb pH gradients of organelles and allow Ca2+ flux across ER membranes. Viroporins interact with numerous intracellular proteins and pathways and can trigger inflammatory responses. Thus, they are relevant targets in the search for antiviral drugs. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) underlies the world-wide pandemic of COVID-19, where an effective therapy is still lacking despite impressive progress in the development of vaccines and vaccination campaigns. Among the 29 proteins of SARS-CoV-2, the E- and ORF3a proteins have been identified as viroporins that contribute to the massive release of inflammatory cytokines observed in COVID-19. Here, we describe structure and function of viroporins and their role in inflammasome activation and cellular processes during the virus replication cycle. Techniques to study viroporin function are presented, with a focus on cellular and electrophysiological assays. Contributions of SARS-CoV-2 viroporins to the viral life cycle are discussed with respect to their structure, channel function, binding partners, and their role in viral infection and virus replication. Viroporin sequences of new variants of concern (α–ο) of SARS-CoV-2 are briefly reviewed as they harbour changes in E and 3a proteins that may affect their function.
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Affiliation(s)
- Ulrike Breitinger
- Department of Biochemistry, German University in Cairo, New Cairo, Egypt
| | - Noha S Farag
- Department of Microbiology and Immunology, German University in Cairo, New Cairo, Egypt
| | - Heinrich Sticht
- Division of Bioinformatics, Institute for Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany
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Saurav S, Tanwar J, Ahuja K, Motiani RK. Dysregulation of host cell calcium signaling during viral infections: Emerging paradigm with high clinical relevance. Mol Aspects Med 2021; 81:101004. [PMID: 34304899 PMCID: PMC8299155 DOI: 10.1016/j.mam.2021.101004] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/18/2021] [Accepted: 07/16/2021] [Indexed: 12/22/2022]
Abstract
Viral infections are one of the leading causes of human illness. Viruses take over host cell signaling cascades for their replication and infection. Calcium (Ca2+) is a versatile and ubiquitous second messenger that modulates plethora of cellular functions. In last two decades, a critical role of host cell Ca2+ signaling in modulating viral infections has emerged. Furthermore, recent literature clearly implicates a vital role for the organellar Ca2+ dynamics (influx and efflux across organelles) in regulating virus entry, replication and severity of the infection. Therefore, it is not surprising that a number of viral infections including current SARS-CoV-2 driven COVID-19 pandemic are associated with dysregulated Ca2+ homeostasis. The focus of this review is to first discuss the role of host cell Ca2+ signaling in viral entry, replication and egress. We further deliberate on emerging literature demonstrating hijacking of the host cell Ca2+ dynamics by viruses. In particular, a variety of viruses including SARS-CoV-2 modulate lysosomal and cytosolic Ca2+ signaling for host cell entry and replication. Moreover, we delve into the recent studies, which have demonstrated the potential of several FDA-approved drugs targeting Ca2+ handling machinery in inhibiting viral infections. Importantly, we discuss the prospective of targeting intracellular Ca2+ signaling for better management and treatment of viral pathogenesis including COVID-19. Finally, we highlight the key outstanding questions in the field that demand critical and timely attention.
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Affiliation(s)
- Suman Saurav
- Laboratory of Calciomics and Systemic Pathophysiology, Regional Centre for Biotechnology (RCB), Faridabad-121001, Delhi-NCR, India
| | - Jyoti Tanwar
- CSIR-Institute of Genomics and Integrative Biology (IGIB), New Delhi-110025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Kriti Ahuja
- Laboratory of Calciomics and Systemic Pathophysiology, Regional Centre for Biotechnology (RCB), Faridabad-121001, Delhi-NCR, India
| | - Rajender K Motiani
- Laboratory of Calciomics and Systemic Pathophysiology, Regional Centre for Biotechnology (RCB), Faridabad-121001, Delhi-NCR, India.
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Hoxie I, Dennehy JJ. Rotavirus A Genome Segments Show Distinct Segregation and Codon Usage Patterns. Viruses 2021; 13:v13081460. [PMID: 34452326 PMCID: PMC8402926 DOI: 10.3390/v13081460] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/05/2021] [Accepted: 07/07/2021] [Indexed: 12/29/2022] Open
Abstract
Reassortment of the Rotavirus A (RVA) 11-segment dsRNA genome may generate new genome constellations that allow RVA to expand its host range or evade immune responses. Reassortment may also produce phylogenetic incongruities and weakly linked evolutionary histories across the 11 segments, obscuring reassortment-specific epistasis and changes in substitution rates. To determine the co-segregation patterns of RVA segments, we generated time-scaled phylogenetic trees for each of the 11 segments of 789 complete RVA genomes isolated from mammalian hosts and compared the segments’ geodesic distances. We found that segments 4 (VP4) and 9 (VP7) occupied significantly different tree spaces from each other and from the rest of the genome. By contrast, segments 10 and 11 (NSP4 and NSP5/6) occupied nearly indistinguishable tree spaces, suggesting strong co-segregation. Host-species barriers appeared to vary by segment, with segment 9 (VP7) presenting the weakest association with host species. Bayesian Skyride plots were generated for each segment to compare relative genetic diversity among segments over time. All segments showed a dramatic decrease in diversity around 2007 coinciding with the introduction of RVA vaccines. To assess selection pressures, codon adaptation indices and relative codon deoptimization indices were calculated with respect to different host genomes. Codon usage varied by segment with segment 11 (NSP5) exhibiting significantly higher adaptation to host genomes. Furthermore, RVA codon usage patterns appeared optimized for expression in humans and birds relative to the other hosts examined, suggesting that translational efficiency is not a barrier in RVA zoonosis.
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Affiliation(s)
- Irene Hoxie
- Biology Department, The Graduate Center, The City University of New York, New York, NY 10016, USA;
- Biology Department, Queens College, The City University of New York, Flushing, New York, NY 11367, USA
- Correspondence:
| | - John J. Dennehy
- Biology Department, The Graduate Center, The City University of New York, New York, NY 10016, USA;
- Biology Department, Queens College, The City University of New York, Flushing, New York, NY 11367, USA
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Sarkar R, Nandi S, Lo M, Gope A, Chawla-Sarkar M. Viperin, an IFN-Stimulated Protein, Delays Rotavirus Release by Inhibiting Non-Structural Protein 4 (NSP4)-Induced Intrinsic Apoptosis. Viruses 2021; 13:1324. [PMID: 34372530 PMCID: PMC8310278 DOI: 10.3390/v13071324] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/19/2021] [Accepted: 06/23/2021] [Indexed: 12/27/2022] Open
Abstract
Viral infections lead to expeditious activation of the host's innate immune responses, most importantly the interferon (IFN) response, which manifests a network of interferon-stimulated genes (ISGs) that constrain escalating virus replication by fashioning an ill-disposed environment. Interestingly, most viruses, including rotavirus, have evolved numerous strategies to evade or subvert host immune responses to establish successful infection. Several studies have documented the induction of ISGs during rotavirus infection. In this study, we evaluated the induction and antiviral potential of viperin, an ISG, during rotavirus infection. We observed that rotavirus infection, in a stain independent manner, resulted in progressive upregulation of viperin at increasing time points post-infection. Knockdown of viperin had no significant consequence on the production of total infectious virus particles. Interestingly, substantial escalation in progeny virus release was observed upon viperin knockdown, suggesting the antagonistic role of viperin in rotavirus release. Subsequent studies unveiled that RV-NSP4 triggered relocalization of viperin from the ER, the normal residence of viperin, to mitochondria during infection. Furthermore, mitochondrial translocation of NSP4 was found to be impeded by viperin, leading to abridged cytosolic release of Cyt c and subsequent inhibition of intrinsic apoptosis. Additionally, co-immunoprecipitation studies revealed that viperin associated with NSP4 through regions including both its radical SAM domain and its C-terminal domain. Collectively, the present study demonstrated the role of viperin in restricting rotavirus egress from infected host cells by modulating NSP4 mediated apoptosis, highlighting a novel mechanism behind viperin's antiviral action in addition to the intricacy of viperin-virus interaction.
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Affiliation(s)
| | | | | | | | - Mamta Chawla-Sarkar
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road Scheme-XM, Beliaghata, Kolkata 700010, India; (R.S.); (S.N.); (M.L.); (A.G.)
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12
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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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13
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Rotavirus Calcium Dysregulation Manifests as Dynamic Calcium Signaling in the Cytoplasm and Endoplasmic Reticulum. Sci Rep 2019; 9:10822. [PMID: 31346185 PMCID: PMC6658527 DOI: 10.1038/s41598-019-46856-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/04/2019] [Indexed: 02/08/2023] Open
Abstract
Like many viruses, rotavirus (RV) dysregulates calcium homeostasis by elevating cytosolic calcium ([Ca2+]cyt) and decreasing endoplasmic reticulum (ER) stores. While an overall, monophasic increase in [Ca2+]cyt during RV infection has been shown, the nature of the RV-induced aberrant calcium signals and how they manifest over time at the single-cell level have not been characterized. Thus, we generated cell lines and human intestinal enteroids (HIEs) stably expressing cytosolic and/or ER-targeted genetically-encoded calcium indicators to characterize calcium signaling throughout RV infection by time-lapse imaging. We found that RV induces highly dynamic [Ca2+]cyt signaling that manifest as hundreds of discrete [Ca2+]cyt spikes, which increase during peak infection. Knockdown of nonstructural protein 4 (NSP4) attenuates the [Ca2+]cyt spikes, consistent with its role in dysregulating calcium homeostasis. RV-induced [Ca2+]cyt spikes were primarily from ER calcium release and were attenuated by inhibiting the store-operated calcium entry (SOCE) channel Orai1. RV-infected HIEs also exhibited prominent [Ca2+]cyt spikes that were attenuated by inhibiting SOCE, underlining the relevance of these [Ca2+]cyt spikes to gastrointestinal physiology and role of SOCE in RV pathophysiology. Thus, our discovery that RV increases [Ca2+]cyt by dynamic calcium signaling, establishes a new, paradigm-shifting understanding of the spatial and temporal complexity of virus-induced calcium signaling.
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14
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Moreno-Altamirano MMB, Kolstoe SE, Sánchez-García FJ. Virus Control of Cell Metabolism for Replication and Evasion of Host Immune Responses. Front Cell Infect Microbiol 2019; 9:95. [PMID: 31058096 PMCID: PMC6482253 DOI: 10.3389/fcimb.2019.00095] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/22/2019] [Indexed: 12/11/2022] Open
Abstract
Over the last decade, there has been significant advances in the understanding of the cross-talk between metabolism and immune responses. It is now evident that immune cell effector function strongly depends on the metabolic pathway in which cells are engaged in at a particular point in time, the activation conditions, and the cell microenvironment. It is also clear that some metabolic intermediates have signaling as well as effector properties and, hence, topics such as immunometabolism, metabolic reprograming, and metabolic symbiosis (among others) have emerged. Viruses completely rely on their host's cell energy and molecular machinery to enter, multiply, and exit for a new round of infection. This review explores how viruses mimic, exploit or interfere with host cell metabolic pathways and how, in doing so, they may evade immune responses. It offers a brief outline of key metabolic pathways, mitochondrial function and metabolism-related signaling pathways, followed by examples of the mechanisms by which several viral proteins regulate host cell metabolic activity.
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Affiliation(s)
- María Maximina B Moreno-Altamirano
- Laboratorio de Inmunorregulación, Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Simon E Kolstoe
- School of Health Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Francisco Javier Sánchez-García
- Laboratorio de Inmunorregulación, Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
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15
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Abstract
There is an almost innate urge in human beings to represent reality in a visual form. From rock art in the Paleolithic to images of galaxies, the quotidian and the extraordinary have been visually represented through the ages. Medical and scientific disciplines are no exception. Accurate representation of the human body structures and anatomy based on cadaver dissections was almost not possible up to the Renaissance due to ethical, social, and religious beliefs and objections. The works of Leonardo da Vinci (1452-1519) and others and, later, Andreas Vesalius (1514-1564), who produced De Humanis Corporis Fabrica, are considered landmarks in the history of medicine. During the following centuries medical and scientific illustration relied upon the expertise of physician-artists and scientist-artists until a new paradigm appeared in the realm of scientific (medical) illustration: the invention of photography in the 19th century. Two of the medical disciplines most rapidly influenced by photography were dermatology and pathology, both macro- and microscopic. Physicians rapidly started to use photographs as a tool for consultation, documentation, and education, and large collections of images were amassed by individuals and institutions for these purposes. Photographic images are produced by visible light impressing a light-sensitive material such as a silver halide plate, and nowadays a silicon chip. But photons are reflected by nontransparent objects, including the human skin. Developments in science and technology allowed the use of other types of radiation to reveal internal structures in the human body and, most interestingly, noninvasively. Thus today much of the medical diagnosis and treatment is guided by the so-called medical imaging with the use of these techniques, that is, medical photography, endoscopy, x-ray radiography, computer-aided tomography, magnetic resonance imaging, ultrasonography, thermography, and nuclear medicine functional imaging techniques as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). Some of these techniques are being applied at the microscopic level to study cell structure and even functional changes in real time. All these advancements in science and technology applied to medicine and other disciplines pose the question as to what extent physicians are trading their capabilities as clinicians. Ethics issues add to the complexity of this new era governed by constant changes in scientific paradigms.
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Affiliation(s)
- Fabian Michelangeli
- Biophysics and Biochemistry, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela.
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16
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Ku JK, Heo YJ, Lee KS, Lee BL. Clinical Findings and Neurologic Outcome in Neonatal Encephalopathy With White Matter Injury Accompanied by Rotavirus. J Child Neurol 2018; 33:297-305. [PMID: 29433417 DOI: 10.1177/0883073817753290] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Our objective was to elucidate the clinical characteristics and neurodevelopmental outcomes in neonatal encephalopathy with characteristic white matter injury as compared with other injury patterns on magnetic resonance diffusion-weighted imaging. We conducted a retrospective study comparing clinical and laboratory findings, and neurologic outcomes between 17 newborns with diffuse lesions in the periventricular white matter and white matter tract (group I) and 22 newborns with other patterns (group II). Stool samples indicated that 16 neonates (94.1%) in group I were rotavirus-positive, whereas none in group II had rotavirus infection. Significantly lower calcium levels were found in group I than in group II ( P < .001). Moreover, a more favorable neurodevelopmental outcome was observed in group I than in group II. This study suggests that characteristic white matter injury in neonatal encephalopathy may be related to decreased calcium levels induced by rotavirus, and may have a better neurodevelopmental prognosis than other causes.
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Affiliation(s)
- Jae Kyun Ku
- 1 Department of Pediatrics, Busan Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
| | - Young Jin Heo
- 2 Department of Radiology, Busan Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
| | - Keun Soo Lee
- 3 Department of Neurosurgery, Busan Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
| | - Bo Lyun Lee
- 1 Department of Pediatrics, Busan Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea
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17
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Mukherjee A, Patra U, Bhowmick R, Chawla-Sarkar M. Rotaviral nonstructural protein 4 triggers dynamin-related protein 1-dependent mitochondrial fragmentation during infection. Cell Microbiol 2018; 20:e12831. [PMID: 29444369 DOI: 10.1111/cmi.12831] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 01/06/2018] [Accepted: 02/06/2018] [Indexed: 12/16/2022]
Abstract
Dynamic equilibrium between mitochondrial fission and mitochondrial fusion serves as an important quality control system within cells ensuring cellular vitality and homeostasis. Viruses often target mitochondrial dynamics as a part of their obligatory cellular reprogramming. The present study was undertaken to assess the status and regulation of mitochondrial dynamics during rotavirus infection. Distinct fragmentation of mitochondrial syncytia was observed during late hours of RV (SA11, Wa, A5-13) infection. RV nonstructural protein 4 (NSP4) was identified as the viral trigger for disrupted mitochondrial morphology. Severance of mitochondrial interconnections was found to be a dynamin-related protein 1 (Drp1)-dependent process resulting synergistically from augmented mitochondrial fission and attenuated mitochondrial fusion. Cyclin-dependent kinase 1 was subsequently identified as the cellular kinase responsible for fission-active Ser616 phosphorylation of Drp1. In addition to its positive role in mitochondrial fission, Drp1 also resulted in mitochondrial translocation of E3-ubiquitin ligase Parkin leading to degradation of mitochondrial fusion protein Mitofusin 1. Interestingly, RV-NSP4 was found to interact with and be involved in recruiting fission-active pool of Serine 616 phosphoDrp1 (Ser616 pDrp1) to mitochondria independent of accessory adaptors Mitochondrial fission factor and Fission protein 1 (Fis1). Inhibition of either Drp1 or Ser616 pDrp1 resulted in significant decrease in RV-NSP4-induced intrinsic apoptotic pathway. Overall, this study underscores an efficient strategy utilised by RV to couple apoptosis to mitochondrial fission facilitating dissemination of viral progeny.
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Affiliation(s)
- Arpita Mukherjee
- Division of Virology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Upayan Patra
- Division of Virology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Rahul Bhowmick
- Division of Virology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Mamta Chawla-Sarkar
- Division of Virology, National Institute of Cholera and Enteric Diseases, Kolkata, India
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18
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Olaya Galán NN, Ulloa Rubiano JC, Velez Reyes FA, Fernandez Duarte KP, Salas Cárdenas SP, Gutierrez Fernandez MF. In vitro antiviral activity of Lactobacillus casei and Bifidobacterium adolescentis against rotavirus infection monitored by NSP4 protein production. J Appl Microbiol 2016; 120:1041-51. [PMID: 26801008 DOI: 10.1111/jam.13069] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 12/23/2015] [Accepted: 01/17/2016] [Indexed: 12/19/2022]
Abstract
AIMS The aim of this study was to determine the antiviral activity of four probiotic metabolites (Lactobacillus and Bifidobacetrium species) against rotavirus in vitro infection monitored by the NSP4 protein production and Ca(2+) release. METHODS AND RESULTS The antiviral effect of the metabolites was performed due a comparison between a blocking model and an intracelullar model on MA104 cells, with the response of NSP4 production and Ca(2+) liberation measured by flow cytometry. Significant results were obtained with the metabolites of Lactobacillus casei, and Bifidobacterium adolescentis in the reduction of the protein production (P = 0·04 and P = 0·014) and Ca(2+) liberation (P = 0·094 and P = 0·020) in the intracellular model, which suggests a successful antiviral activity against RV infection. CONCLUSIONS This study demonstrates that probiotic metabolites were able to interfere with the final amount of intracellular NSP4 protein and a successful Ca(2+) regulation, which suggests a new approach to the mechanism exerted by probiotics against the rotavirus infection. SIGNIFICANCE AND IMPACT OF THE STUDY A novel anti-rotaviral effect exerted by probiotic metabolites monitored by the NSP4 protein during the RV in vitro infection and the effect on the Ca(2+) release is reported; suggesting a reduction on the impact of the infection by decreasing the damage of the cells preventing the electrolyte loss.
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Affiliation(s)
- N N Olaya Galán
- Laboratorio de Virología, Grupo de Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - J C Ulloa Rubiano
- Laboratorio de Virología, Grupo de Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - F A Velez Reyes
- Departamento de Matemáticas, Facultad de Ciencias, Universidad El Bosque, Bogotá, Colombia
| | - K P Fernandez Duarte
- Laboratorio de Virología, Grupo de Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - S P Salas Cárdenas
- Laboratorio de Virología, Grupo de Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - M F Gutierrez Fernandez
- Laboratorio de Virología, Grupo de Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia
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19
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Popkov VA, Zorova LD, Korvigo IO, Silachev DN, Jankauskas SS, Babenko VA, Pevzner IB, Danilina TI, Zorov SD, Plotnikov EY, Zorov DB. Do Mitochondria Have an Immune System? BIOCHEMISTRY (MOSCOW) 2016; 81:1229-1236. [PMID: 27908248 DOI: 10.1134/s0006297916100217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The question if mitochondria have some kind of immune system is not trivial. The basis for raising this question is the fact that bacteria, which are progenitors of mitochondria, do have an immune system. The CRISPR system in bacteria based on the principle of RNA interference serves as an organized mechanism for destroying alien nucleic acids, primarily those of viral origin. We have shown that mitochondria are also a target for viral attacks, probably due to a related organization of genomes in these organelles and bacteria. Bioinformatic analysis performed in this study has not given a clear answer if there is a CRISPR-like immune system in mitochondria. However, this does not preclude the possibility of mitochondrial immunity that can be difficult to decipher or that is based on some principles other than those of CRISPR.
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Affiliation(s)
- V A Popkov
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, 119991, Russia.
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20
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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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21
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Chattopadhyay S, Mukherjee A, Patra U, Bhowmick R, Basak T, Sengupta S, Chawla-Sarkar M. Tyrosine phosphorylation modulates mitochondrial chaperonin Hsp60 and delays rotavirus NSP4-mediated apoptotic signaling in host cells. Cell Microbiol 2016; 19. [PMID: 27665089 DOI: 10.1111/cmi.12670] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 12/29/2022]
Abstract
Phosphoproteomics-based platforms have been widely used to identify post translational dynamics of cellular proteins in response to viral infection. The present study was undertaken to assess differential tyrosine phosphorylation during early hours of rotavirus (RV) SA11 infection. Heat shock proteins (Hsp60) were found to be enriched in the data set of RV-SA11 induced differentially tyrosine-phosphorylated proteins at 2 hr post infection (hpi). Hsp60 was further found to be phosphorylated by an activated form of Src kinase on 227th tyrosine residue, and tyrosine phosphorylation of mitochondrial chaperonin Hsp60 correlated with its proteasomal degradation at 2-2.5hpi. Interestingly, mitochondrial Hsp60 positively influenced translocation of the rotaviral nonstructural protein 4 to mitochondria during RV infections. Phosphorylation and subsequent transient degradation of mitochondrial Hsp60 during early hours of RV-SA11 infection resulted in inhibition of premature import of nonstructural protein 4 into mitochondria, thereby delaying early apoptosis. Overall, the study highlighted one of the many strategies rotavirus undertakes to prevent early apoptosis and subsequent reduced viral progeny yield.
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Affiliation(s)
- Shiladitya Chattopadhyay
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road SchemeP- XM, Beliaghata, Kolkata, 700010, India
| | - Arpita Mukherjee
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road SchemeP- XM, Beliaghata, Kolkata, 700010, India
| | - Upayan Patra
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road SchemeP- XM, Beliaghata, Kolkata, 700010, India
| | - Rahul Bhowmick
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road SchemeP- XM, Beliaghata, Kolkata, 700010, India
| | - Trayambak Basak
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi, 110020, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-IGIB campus, New Delhi, India
| | - Shantanu Sengupta
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi, 110020, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-IGIB campus, New Delhi, India
| | - Mamta Chawla-Sarkar
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road SchemeP- XM, Beliaghata, Kolkata, 700010, India
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22
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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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23
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The effect of bovine rotavirus and its nonstructural protein 4 on ER stress-mediated apoptosis in HeLa and HT-29 cells. Tumour Biol 2015; 37:3155-61. [PMID: 26427658 DOI: 10.1007/s13277-015-4097-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 09/14/2015] [Indexed: 02/08/2023] Open
Abstract
Endoplasmic reticulum (ER) plays important roles in multiple cellular processes as well as cell survival and apoptosis. Perturbation of ER functions leads to ER stress and unfolded protein response (UPR). The primary goal of this response is cell survival, but severe ER stress can trigger apoptosis signaling. In tumor cells, chronically activated UPR response provides tumor growth. So, apoptosis induced by the ER stress has been the target for anti-cancer therapy. In this in vitro study, we examined the apoptotic effect associated with ER stress of bovine rotavirus and its nonstructural protein 4 (NSP4) alone in two cancer cell lines. The plasmid pcDNA3.1 encoding NSP4 protein of bovine rotavirus transfected with lipofectamine 2000 into the HeLa and HT-29 cells for protein production. MTT, flow cytometry, and Western blot were used to evaluate the cell viability, apoptosis, and expression level of C/EBP-homologous protein (CHOP) and activated caspase-4. In parallel, the apoptotic effect of the bovine rotavirus associated with ER stress in the infected cells was examined too. The cytotoxic and apoptotic effect of NSP4 protein on the cells were statistically significant compared to the control groups. However, Western blot showed that the expression of the NSP4 protein by recombinant plasmid did not lead to high expression of CHOP and activation of caspase-4. Interestingly, rotavirus not only induced significant apoptosis but also caused an increase in CHOP expression and caspase-4 activation in the infected cells compared to control. As a result, NSP4 protein and bovine rotavirus can be considered a potential novel bio-therapeutic strategy for cancer treatment.
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24
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Yeom JS, Kim YS, Kim RB, Park JS, Seo JH, Park E, Lim JY, Park CH, Woo HO, Youn HS. Impact of rotavirus vaccine introduction on rotavirus-associated seizures and a related possible mechanism. J Child Neurol 2015; 30:729-34. [PMID: 25117417 DOI: 10.1177/0883073814542944] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 09/04/2013] [Indexed: 11/15/2022]
Abstract
To determine whether clinical features of rotavirus-associated seizures have been altered by rotavirus vaccination, we compared clinical and laboratory data of 2 groups of patients with rotavirus-associated seizures: pre- and post-vaccine introduction groups. The seizure characteristics differed significantly between the groups, with a lower incidence of fever at seizure onset, longer interval between the onset of gastroenteritis and seizures, and more frequent seizures in the postintroduction group. These characteristics may suggest that seizure susceptibility was increased in the postintroduction group. Based on the lower serum Cl(-) (102.1 ± 4.1 vs 98.2 ± 3.2 mg/dL; P < .01) and Ca(2+) levels (9.2 ± 0.4 vs 9.0 ± 0.3 mg/dL; P = .12) in the postintroduction group, we propose that a change in the subjects' susceptibility to the rotavirus enterotoxin may have played a role in increasing the seizure susceptibility in this group. Our results suggest that a rotavirus vaccination program may modulate the manifestations of rotavirus-associated seizures.
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Affiliation(s)
- Jung Sook Yeom
- Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea Gyeongsang Institute of Health Science, Jinju, Korea
| | - Young-Soo Kim
- Department of Neurology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
| | - Rock Bum Kim
- Department of Preventive Medicine, Dong-A University College of Medicine, Busan, Korea
| | - Ji Sook Park
- Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea Gyeongsang Institute of Health Science, Jinju, Korea
| | - Ji-Hyun Seo
- Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea Gyeongsang Institute of Health Science, Jinju, Korea
| | - Eunsil Park
- Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea Gyeongsang Institute of Health Science, Jinju, Korea
| | - Jae-Young Lim
- Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea Gyeongsang Institute of Health Science, Jinju, Korea
| | - Chan-Hoo Park
- Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea Gyeongsang Institute of Health Science, Jinju, Korea
| | - Hyang-Ok Woo
- Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea Gyeongsang Institute of Health Science, Jinju, Korea
| | - Hee-Shang Youn
- Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea Gyeongsang Institute of Health Science, Jinju, Korea
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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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Kang B, Kwon YS. Benign convulsion with mild gastroenteritis. KOREAN JOURNAL OF PEDIATRICS 2014; 57:304-9. [PMID: 25114690 PMCID: PMC4127392 DOI: 10.3345/kjp.2014.57.7.304] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 06/03/2014] [Indexed: 12/29/2022]
Abstract
Benign convulsion with mild gastroenteritis (CwG) is a type of afebrile seizure that occurs in children. CwG is defined as a convulsion in a previously healthy child with no known central nervous system infection or encephalopathy, accompanying mild diarrhea without fever, electrolyte imbalance, or moderate to severe dehydration. Convulsions in CwG are characterized by multiple brief episodes of generalized or focal seizures. Although the etiology and pathophysiology have yet to be fully explained, many pathogenic mechanisms have been proposed including the possibility of direct invasion of the central nervous system by a gastrointestinal virus such as rotavirus or the possibility of indirect influence by the production and effects of certain mediators. The electroencephalogram findings are benign and long-term antiepileptic treatment is typically not required. Long-term prognosis has been favorable with normal psychomotor development. This review provides a general overview of CwG with the goal of allowing physicians practicing in the field of pediatrics to better recognize this unique entity and, ultimately, to minimize unnecessary evaluation and treatment.
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Affiliation(s)
- Ben Kang
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Young Se Kwon
- Department of Pediatrics, Inha University Hospital, Incheon, Korea
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Yeom JS, Kim YS, Park JS, Seo JH, Park ES, Lim JY, Park CH, Woo HO, Youn HS. Role of Ca2+ homeostasis disruption in rotavirus-associated seizures. J Child Neurol 2014; 29:331-5. [PMID: 23271755 DOI: 10.1177/0883073812469052] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Rotavirus infection disturbs cellular Ca(2+) homeostasis by triggering an increase in Ca(2+) permeation. A theoretical link between Ca(2+) dysregulation and seizures in patients with rotavirus gastroenteritis has been suggested, but no prior studies have investigated this relationship. To test our hypothesis that patients with rotavirus-associated seizures have greater Ca(2+) homeostasis disruption than those without seizures, we compared clinical and laboratory data--including corrected total serum Ca(2+) levels--between the 2 groups. Age, gender, maximum body temperature, day of admission, levels of electrolytes except Ca(2+), blood pH, and urine ketone levels were not related to seizure occurrence. Significantly lower Ca(2+) levels were found among the seizure (+) group (9.22 ± 0.50 vs 9.66 ± 0.46 mg/dL, P = .01). Although Ca(2+) levels were within normal ranges and did not directly cause the seizures, our results provide preliminary evidence for a relationship between Ca(2+) homeostasis disruption and seizures in rotavirus patients.
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Affiliation(s)
- Jung Sook Yeom
- 1Department of Pediatrics, Gyeongsang National University School of Medicine, Jinju, Korea
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Anand SK, Tikoo SK. Viruses as modulators of mitochondrial functions. Adv Virol 2013; 2013:738794. [PMID: 24260034 PMCID: PMC3821892 DOI: 10.1155/2013/738794] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/30/2013] [Indexed: 02/07/2023] Open
Abstract
Mitochondria are multifunctional organelles with diverse roles including energy production and distribution, apoptosis, eliciting host immune response, and causing diseases and aging. Mitochondria-mediated immune responses might be an evolutionary adaptation by which mitochondria might have prevented the entry of invading microorganisms thus establishing them as an integral part of the cell. This makes them a target for all the invading pathogens including viruses. Viruses either induce or inhibit various mitochondrial processes in a highly specific manner so that they can replicate and produce progeny. Some viruses encode the Bcl2 homologues to counter the proapoptotic functions of the cellular and mitochondrial proteins. Others modulate the permeability transition pore and either prevent or induce the release of the apoptotic proteins from the mitochondria. Viruses like Herpes simplex virus 1 deplete the host mitochondrial DNA and some, like human immunodeficiency virus, hijack the host mitochondrial proteins to function fully inside the host cell. All these processes involve the participation of cellular proteins, mitochondrial proteins, and virus specific proteins. This review will summarize the strategies employed by viruses to utilize cellular mitochondria for successful multiplication and production of progeny virus.
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Affiliation(s)
- Sanjeev K. Anand
- Vaccine & Infection Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- Veterinary Microbiology, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
| | - Suresh K. Tikoo
- Vaccine & Infection Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- Veterinary Microbiology, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- School of Public Health, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
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Activation of the endoplasmic reticulum calcium sensor STIM1 and store-operated calcium entry by rotavirus requires NSP4 viroporin activity. J Virol 2013; 87:13579-88. [PMID: 24109210 DOI: 10.1128/jvi.02629-13] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Rotavirus nonstructural protein 4 (NSP4) induces dramatic changes in cellular calcium homeostasis. These include increased endoplasmic reticulum (ER) permeability, resulting in decreased ER calcium stores and activation of plasma membrane (PM) calcium influx channels, ultimately causing a 2- to 4-fold elevation in cytoplasmic calcium. Elevated cytoplasmic calcium is absolutely required for virus replication, but the underlying mechanisms responsible for calcium influx remain poorly understood. NSP4 is an ER-localized viroporin, whose activity depletes ER calcium, which ultimately leads to calcium influx. We hypothesized that NSP4-mediated depletion of ER calcium activates store-operated calcium entry (SOCE) through activation of the ER calcium sensor stromal interaction molecule 1 (STIM1). We established and used a stable yellow fluorescent protein-expressing STIM1 cell line (YFP-STIM1) as a biosensor to assess STIM1 activation (puncta formation) by rotavirus infection and NSP4 expression. We found that STIM1 is constitutively active in rotavirus-infected cells and that STIM1 puncta colocalize with the PM-localized Orai1 SOCE calcium channel. Expression of wild-type NSP4 activated STIM1, resulting in PM calcium influx, but an NSP4 viroporin mutant failed to induce STIM1 activation and did not activate the PM calcium entry pathway. Finally, knockdown of STIM1 significantly reduced rotavirus yield, indicating STIM1 plays a critical role in virus replication. These data demonstrate that while rotavirus may ultimately activate multiple calcium channels in the PM, calcium influx is predicated on NSP4 viroporin-mediated activation of STIM1 in the ER. This is the first report of viroporin-mediated activation of SOCE, reinforcing NSP4 as a robust model to understand dysregulation of calcium homeostasis during virus infections.
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Abstract
Rotavirus is an important gastrointestinal pathogen which can cause severe diarrhea in young animals and infants. Although rotavirus infections are usually latent, large-scale outbreak may occur if environmental factors change or the immune defense of hosts decreases. As rotavirus is a pathogen of zoonotic diseases, studies on rotavirus infections are of great importance in public health and clinical application. This article provides an overview of the progress in research on viral pathogen, clinical manifestations, as well as drug and vaccine research, with an aim to provide a reference for the prevention and treatment of rotavirus infections.
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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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Abstract
Viroporins are small virally encoded hydrophobic proteins that oligomerize in the membrane of host cells, leading to the formation of hydrophilic pores. This activity modifies several cellular functions, including membrane permeability, Ca2+ homeostasis, membrane remodelling and glycoprotein trafficking. A classification scheme for viroporins is proposed on the basis of their structure and membrane topology. Thus, class I and class II viroporins are defined according to the number of transmembrane domains in the protein (one and two, respectively), and subclasses are defined according to their orientation in the membrane. The main function of viroporins during viral replication is to participate in virion morphogenesis and release from host cells. In addition, some viroporins are involved in viral entry and genome replication. The structure and activity of several viroporins, such as picornavirus protein 2B (P2B), influenza A virus matrix protein 2 (M2), hepatitis C virus p7 and HIV-1 viral protein U (Vpu), have been analysed in detail. New members of this expanding family of viral proteins have been described, from both RNA and DNA viruses. In addition to having a common general structure, all of these new viroporins have the ability to increase membrane permeability. Viroporins represent ideal targets to block viral replication and the spread of infection. Although a number of selective inhibitors of viroporin ion channels have been analysed in detail, optimized screening systems promise to provide new and more potent antiviral compounds in the near future.
Viroporins belong to a growing family of virally encoded proteins that form aqueous channels in the membranes of host cells. Here, Carrasco and colleagues review the structure and diverse biological functions of these proteins during the viral life cycle, as well as their potential as antiviral therapeutic targets. Viroporins are small, hydrophobic proteins that are encoded by a wide range of clinically relevant animal viruses. When these proteins oligomerize in host cell membranes, they form hydrophilic pores that disrupt a number of physiological properties of the cell. Viroporins are crucial for viral pathogenicity owing to their involvement in several diverse steps of the viral life cycle. Thus, these viral proteins, which include influenza A virus matrix protein 2 (M2), HIV-1 viral protein U (Vpu) and hepatitis C virus p7, represent ideal targets for therapeutic intervention, and several compounds that block their pore-forming activity have been identified. Here, we review recent studies in the field that have advanced our knowledge of the structure and function of this expanding family of viral proteins.
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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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Genetic divergence of rotavirus nonstructural protein 4 results in distinct serogroup-specific viroporin activity and intracellular punctate structure morphologies. J Virol 2012; 86:4921-34. [PMID: 22357281 DOI: 10.1128/jvi.06759-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Nonstructural protein 4 (NSP4) viroporin activity is critical for the replication and assembly of serogroup A rotavirus (RVA); however, the dramatic primary sequence divergence of NSP4s across serogroups raises the possibility that viroporin activity is not a common feature among RVs. We tested for NSP4 viroporin activity from divergent strains, including RVA (EC and Ty-1), RVB (IDIR), and RVC (Cowden). Canonical viroporin motifs were identified in RVA, RVB, and RVC NSP4s, but the arrangement of basic residues and the amphipathic α-helices was substantially different between serogroups. Using Escherichia coli and mammalian cell expression, we showed that each NSP4 tested had viroporin activity, but serogroup-specific viroporin phenotypes were identified. Only mammalian RVA and RVC NSP4s induced BL21-pLysS E. coli cell lysis, a classical viroporin activity assay. In contrast, RVA, RVB, and RVC NSP4 expression was universally cytotoxic to E. coli and disrupted reduction-oxidation activities, as measured by a new redox dye assay. In mammalian cells, RVB and RVC NSP4s were initially localized in the endoplasmic reticulum (ER) and trafficked into punctate structures that were mutually exclusive with RVA NSP4. The punctate structures partially localized to the ER-Golgi intermediate compartment (ERGIC) but primarily colocalized with punctate LC3, a marker for autophagosomes. Similar to RVA NSP4, expression of RVB and RVC NSP4s significantly elevated cytosolic calcium levels, demonstrating that despite strong primary sequence divergence, RV NSP4 has maintained viroporin activity across serogroups A to C. These data suggest that elevated cytosolic calcium is a common critical process for all rotavirus strains.
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Abstract
Diarrhea, a disease of poverty and poor sanitation, kills an estimated two million children each year. Oral rehydration therapy is a very simple and inexpensive treatment that has significantly reduced mortality from secretory diarrhea caused by rotavirus, cholera and enterotoxigenic Escherichia coli. The efficacy and adoption of oral rehydration therapy would be enhanced by a drug that reduces fluid loss associated with these diseases and alleviates disease symptoms. Secretion and absorption by the intestine offer a number of potential drug targets to reduce fluid loss. Among these, the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is the most attractive because it is the primary driver of secretion in cases of diarrhea caused by enterotoxigenic bacteria. CFTR can be inhibited by both natural products and synthetic small molecules. iOWH032 is a synthetic CFTR inhibitor that has recently entered clinical trials for this indication.
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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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Yang W, McCrae MA. The rotavirus enterotoxin (NSP4) promotes re-modeling of the intracellular microtubule network. Virus Res 2011; 163:269-74. [PMID: 22036730 DOI: 10.1016/j.virusres.2011.10.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 10/14/2011] [Accepted: 10/15/2011] [Indexed: 01/07/2023]
Abstract
Expression of the rotavirus enterotoxin (NSP4) in transfected monkey kidney cells was found to result in a dramatic re-modeling of the microtubule (MT) network. This important centrosome organized cytoskeletal element was dissolved by expression of NSP4 and re-formed in a ring array at the periphery of the cell, similar to that seen following normal virus infection. Site directed mutagenesis of the N-linked glycosylation sites in NSP4 was employed to show that glycosylation of NSP4 was not required for it to promote changes in the MT network. This result together with experiments using conventional inhibitors indicated that NSP4's ability to cause elevation of intracellular calcium levels was also not necessary to effect the changes in the MT network. Use of the centrosome function inhibitor nocodazole demonstrated that NSP4 based remodeling of the MT network was dominant over the normal organizational role of the centrosome. Finally the remodeling of the MT network was shown not to be linked to cellular apoptosis or necrosis. The potential importance of this newly recognised role for NSP4 in the overall process of intracellular pathogenesis by rotaviruses is discussed.
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Affiliation(s)
- Weiming Yang
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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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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Zambrano JL, Ettayebi K, Maaty WS, Faunce NR, Bothner B, Hardy ME. Rotavirus infection activates the UPR but modulates its activity. Virol J 2011; 8:359. [PMID: 21774819 PMCID: PMC3149005 DOI: 10.1186/1743-422x-8-359] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 07/20/2011] [Indexed: 12/15/2022] Open
Abstract
Background Rotaviruses are known to modulate the innate antiviral defense response driven by IFN. The purpose of this study was to identify changes in the cellular proteome in response to rotavirus infection in the context of the IFN response. We also sought to identify proteins outside the IFN induction and signaling pathway that were modulated by rotavirus infection. Methods 2D-DIGE and image analysis were used to identify cellular proteins that changed in levels of expression in response to rotavirus infection, IFN treatment, or IFN treatment prior to infection. Immunofluorescence microscopy was used to determine the subcellular localization of proteins associated with the unfolded protein response (UPR). Results The data show changes in the levels of multiple proteins associated with cellular stress in infected cells, including levels of ER chaperones GRP78 and GRP94. Further investigations showed that GRP78, GRP94 and other proteins with roles in the ER-initiated UPR including PERK, CHOP and GADD34, were localized to viroplasms in infected cells. Conclusions Together the results suggest rotavirus infection activates the UPR, but modulates its effects by sequestering sensor, transcription factor, and effector proteins in viroplasms. The data consequently also suggest that viroplasms may directly or indirectly play a fundamental role in regulating signaling pathways associated with cellular defense responses.
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Affiliation(s)
- Jose Luis Zambrano
- Immunology and Infectious Diseases, Montana State University, Bozeman, MT 59718, USA
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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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Chen F, Wang H, He H, Song L, Wu J, Gao Y, Liu X, He C, Yang H, Chen L, Wang L, Li G, Li Y, Kaplan DE, Zhong J. Short hairpin RNA-mediated silencing of bovine rotavirus NSP4 gene prevents diarrhoea in suckling mice. J Gen Virol 2010; 92:945-51. [PMID: 21148273 DOI: 10.1099/vir.0.027680-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
While RNA interference (RNAi) has been widely used to study rotavirus gene function in vitro, the potential therapeutic role for RNAi in vivo has not been explored. To this end, we constructed two recombinant lentiviral vectors containing short hairpin RNA (shRNA) against non-structural protein-4 (NSP4) of bovine rotavirus (BRV), RNAi-351 and RNAi-492. RNAi-351 and RNAi-492 strongly suppressed the transient expression of a FLAG-tagged NSP4 fusion protein in 293T cells. In BRV-susceptible MA104 cells, RNAi-492 more potently silenced NSP4 mRNA than RNAi-351 and combination of the two shRNAs almost completely silenced viral NSP4 gene expression. While 100% of suckling mice exposed to BRV and control shRNA developed severe diarrhoea, no suckling mice exposed to BRV in the presence of RNAi-492 or a combination of RNAi-492/RNAi-351 developed severe diarrhoea, and only 20 and 3.3% developed mild diarrhoea, respectively. In addition, RNAi-492 and RNAi-351 markedly abrogated rotaviral replication in MA104 cells and significantly inhibited BRV replication in mouse pups. These results indicated that shRNAs silencing NSP4 gene had substantial antiviral properties and inhibited replication of BRV in a sequence-specific manner that may have clinical application.
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Affiliation(s)
- Fangyuan Chen
- Dairy Cattle Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
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Rotavirus disrupts calcium homeostasis by NSP4 viroporin activity. mBio 2010; 1. [PMID: 21151776 PMCID: PMC2999940 DOI: 10.1128/mbio.00265-10] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 10/27/2010] [Indexed: 12/22/2022] Open
Abstract
Many viruses alter intracellular calcium homeostasis. The rotavirus nonstructural protein 4 (NSP4), an endoplasmic reticulum (ER) transmembrane glycoprotein, increases intracellular levels of cytoplasmic Ca2+ ([Ca2+]cyto) through a phospholipase C-independent pathway, which is required for virus replication and morphogenesis. However, the NSP4 domain and mechanism that increases [Ca2+]cyto are unknown. We identified an NSP4 domain (amino acids [aa] 47 to 90) that inserts into membranes and has structural characteristics of viroporins, a class of small hydrophobic viral proteins that disrupt membrane integrity and ion homeostasis to facilitate virus entry, assembly, or release. Mutational analysis showed that NSP4 viroporin activity was mediated by an amphipathic α-helical domain downstream of a conserved lysine cluster. The lysine cluster directed integral membrane insertion of the viroporin domain and was critical for viroporin activity. In epithelial cells, expression of wild-type NSP4 increased the levels of free cytoplasmic Ca2+ by 3.7-fold, but NSP4 viroporin mutants maintained low levels of [Ca2+]cyto, were retained in the ER, and failed to form cytoplasmic vesicular structures, called puncta, which surround viral replication and assembly sites in rotavirus-infected cells. When [Ca2+]cyto was increased pharmacologically with thapsigargin, viroporin mutants formed puncta, showing that elevation of calcium levels and puncta formation are distinct functions of NSP4 and indicating that NSP4 directly or indirectly responds to elevated cytoplasmic calcium levels. NSP4 viroporin activity establishes the mechanism for NSP4-mediated elevation of [Ca2+]cyto, a critical event that regulates rotavirus replication and virion assembly. Rotavirus is the leading cause of viral gastroenteritis in children and young animals. Rotavirus infection and expression of nonstructural protein 4 (NSP4) alone dramatically increase cytosolic calcium, which is essential for replication and assembly of infectious virions. This work identifies the intracellular mechanism by which NSP4 disrupts calcium homeostasis by showing that NSP4 is a viroporin, a class of virus-encoded transmembrane pores. Mutational analyses identified residues critical for viroporin activity. Viroporin mutants did not elevate the levels of cytoplasmic calcium in mammalian cells and were maintained in the endoplasmic reticulum rather than forming punctate vesicular structures that are critical for virus replication and morphogenesis. Pharmacological elevation of cytoplasmic calcium levels rescued puncta formation in viroporin mutants, demonstrating that elevation of calcium levels and puncta formation are distinct NSP4 functions. While viroporins typically function in virus entry or release, elevation of calcium levels by NSP4 viroporin activity may serve as a regulatory function to facilitate virus replication and assembly.
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Toxin mediated diarrhea in the 21 century: the pathophysiology of intestinal ion transport in the course of ETEC, V. cholerae and rotavirus infection. Toxins (Basel) 2010; 2:2132-57. [PMID: 22069677 PMCID: PMC3153279 DOI: 10.3390/toxins2082132] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 08/09/2010] [Indexed: 12/31/2022] Open
Abstract
An estimated 4 billion episodes of diarrhea occur each year. As a result, 2–3 million children and 0.5–1 million adults succumb to the consequences of this major healthcare concern. The majority of these deaths can be attributed to toxin mediated diarrhea by infectious agents, such as E. coli, V. cholerae or Rotavirus. Our understanding of the pathophysiological processes underlying these infectious diseases has notably improved over the last years. This review will focus on the cellular mechanism of action of the most common enterotoxins and the latest specific therapeutic approaches that have been developed to contain their lethal effects.
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