scholarly journals SARS-CoV-2 Cellular Infection and Therapeutic Opportunities: Lessons Learned from Ebola Virus

Membranes ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 64
Author(s):  
Jordana Muñoz-Basagoiti ◽  
Daniel Perez-Zsolt ◽  
Jorge Carrillo ◽  
Julià Blanco ◽  
Bonaventura Clotet ◽  
...  
Keyword(s):  
Viral Entry ◽  
Ebola Virus ◽  
Lessons Learned ◽  
Productive Infection ◽  
Target Cells ◽  
Emerging Viruses ◽  
Highly Pathogenic ◽  
Life Threatening ◽  
Pathogenic Viruses ◽  
Cellular Machinery

Viruses rely on the cellular machinery to replicate and propagate within newly infected individuals. Thus, viral entry into the host cell sets up the stage for productive infection and disease progression. Different viruses exploit distinct cellular receptors for viral entry; however, numerous viral internalization mechanisms are shared by very diverse viral families. Such is the case of Ebola virus (EBOV), which belongs to the filoviridae family, and the recently emerged coronavirus SARS-CoV-2. These two highly pathogenic viruses can exploit very similar endocytic routes to productively infect target cells. This convergence has sped up the experimental assessment of clinical therapies against SARS-CoV-2 previously found to be effective for EBOV, and facilitated their expedited clinical testing. Here we review how the viral entry processes and subsequent replication and egress strategies of EBOV and SARS-CoV-2 can overlap, and how our previous knowledge on antivirals, antibodies, and vaccines against EBOV has boosted the search for effective countermeasures against the new coronavirus. As preparedness is key to contain forthcoming pandemics, lessons learned over the years by combating life-threatening viruses should help us to quickly deploy effective tools against novel emerging viruses.

scholarly journals Signal-regulatory protein alpha is an anti-viral entry factor targeting viruses using endocytic pathways

2021 ◽  
Vol 17 (6) ◽  
pp. e1009662
Author(s):  
Nicolás Sarute ◽  
Han Cheng ◽  
Zhonghao Yan ◽  
Karen Salas-Briceno ◽  
Justin Richner ◽  
...  
Keyword(s):  
Viral Entry ◽  
New World ◽  
Ebola Virus ◽  
Regulatory Protein ◽  
Target Cells ◽  
Surface Receptors ◽  
Tacaribe Virus ◽  
Targeted Mutation ◽  
Pathogenic Viruses

Signal-regulatory protein alpha (SIRPA) is a well-known inhibitor of phagocytosis when it complexes with CD47 expressed on target cells. Here we show that SIRPA decreased in vitro infection by a number of pathogenic viruses, including New World and Old world arenaviruses, Zika virus, vesicular stomatitis virus and pseudoviruses bearing the Machupo virus, Ebola virus and SARS-CoV-2 glycoproteins, but not HSV-1, MLV or mNoV. Moreover, mice with targeted mutation of the Sirpa gene that renders it non-functional were more susceptible to infection with the New World arenaviruses Junín virus vaccine strain Candid 1 and Tacaribe virus, but not MLV or mNoV. All SIRPA-inhibited viruses have in common the requirement for trafficking to a low pH endosomal compartment. This was clearly demonstrated with SARS-CoV-2 pseudovirus, which was only inhibited by SIRPA in cells in which it required trafficking to the endosome. Similar to its role in phagocytosis inhibition, SIRPA decreased virus internalization but not binding to cell surface receptors. We also found that increasing SIRPA levels via treatment with IL-4 led to even greater anti-viral activity. These data suggest that enhancing SIRPA’s activity could be a target for anti-viral therapies.

In Silico Perspective into Interactions and Mutations in Human TLR4 and Ebola Glycoprotein

2016 ◽  
pp. 209-231
Author(s):  
Sujay Ray ◽  
Arundhati Banerjee
Keyword(s):  
Viral Entry ◽  
Ebola Virus ◽  
Solvent Accessibility ◽  
Human Protein ◽  
Laboratory Research ◽  
Virus Infections ◽  
Conformational Switching ◽  
Toll Like Receptor 4 ◽  
Multiple Sequence ◽  
Life Threatening

Toll-Like Receptor-4 (TLR4) senses life-threatening Ebola virus Glycoprotein (GP) and produces pro-inflammatory cytokines, resulting in lethal Ebola virus infections. GP2-subunit of Ebola promotes viral entry via membrane fusion. The present study models, optimizes and demonstrates the 3D monomer of the responsible human protein. The essential residue (studied from wet-laboratory research) was observed to be functionally conserved from multiple-sequence alignment. Thus, after performing point-mutation, the mutant protein was satisfactorily re-modelled; keeping its functionality preserved. Comparable residual participation in GP2 and each of the proteins was examined, individually. Stability of the proteins and protein-GP2 complexes on mutation; were discerned via energy calculations, solvent-accessibility area and conformational switching, with supportive statistical significances. Therefore, this probe paves a pathway to examine the weaker interaction of the stable mutated human protein with Ebola GP2 protein, thereby defending the Ebola viral entry.

scholarly journals Nosocomial Transmission of Emerging Viruses via Aerosol-Generating Medical Procedures

Viruses ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 940 ◽  
Author(s):  
Seth D. Judson ◽  
Vincent J. Munster
Keyword(s):  
Health Care ◽  
Ebola Virus ◽  
Viral Infections ◽  
Nipah Virus ◽  
Hemorrhagic Fever ◽  
Nosocomial Transmission ◽  
Medical Procedures ◽  
Emerging Viruses ◽  
Pathogenic Viruses ◽  
Infection Control Guidelines

Recent nosocomial transmission events of emerging and re-emerging viruses, including Ebola virus, Middle East respiratory syndrome coronavirus, Nipah virus, and Crimean–Congo hemorrhagic fever orthonairovirus, have highlighted the risk of nosocomial transmission of emerging viruses in health-care settings. In particular, concerns and precautions have increased regarding the use of aerosol-generating medical procedures when treating patients with such viral infections. In spite of increasing associations between aerosol-generating medical procedures and the nosocomial transmission of viruses, we still have a poor understanding of the risks of specific procedures and viruses. In order to identify which aerosol-generating medical procedures and emerging viruses pose a high risk to health-care workers, we explore the mechanisms of aerosol-generating medical procedures, as well as the transmission pathways and characteristics of highly pathogenic viruses associated with nosocomial transmission. We then propose how research, both in clinical and experimental settings, could advance current infection control guidelines.

scholarly journals Establishment of a well-characterized SARS-CoV-2 lentiviral pseudovirus neutralization assay using 293T cells with stable expression of ACE2 and TMPRSS2

2020 ◽  
Author(s):  
Sabari Nath Neerukonda ◽  
Russell Vassell ◽  
Rachel Herrup ◽  
Shufeng Liu ◽  
Tony Wang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
293T Cell ◽  
Neutralization Assay ◽  
Target Cells ◽  
Highly Pathogenic ◽  
Angiotensin Converting Enzyme 2 ◽  
Pathogenic Viruses ◽  
Screening Assays ◽  
Assay Precision ◽  
Transmembrane Serine Protease

AbstractPseudoviruses are useful surrogates for highly pathogenic viruses because of their safety, genetic stability, and scalability for screening assays. Many different pseudovirus platforms exist, each with different advantages and limitations. Here we report our efforts to optimize and characterize an HIV-based lentiviral pseudovirus assay for screening neutralizing antibodies for SARS-CoV-2 using a stable 293T cell line expressing human angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). We assessed different target cells, established conditions that generate readouts over at least a two-log range, and confirmed consistent neutralization titers over a range of pseudovirus input. Using reference sera and plasma panels, we evaluated assay precision and showed that our neutralization titers correlate well with results reported in other assays. Overall, our lentiviral assay is relatively simple, scalable, and suitable for a variety of SARS-CoV-2 entry and neutralization screening assays.

scholarly journals Human Immunodeficiency Virus Type 1 Nef Functions at the Level of Virus Entry by Enhancing Cytoplasmic Delivery of Virions

2001 ◽  
Vol 75 (6) ◽  
pp. 2993-3000 ◽  
Author(s):  
Evelyne Schaeffer ◽  
Romas Geleziunas ◽  
Warner C. Greene
Keyword(s):  
Human Immunodeficiency Virus ◽  
Viral Entry ◽  
Receptor Expression ◽  
Endocytic Pathway ◽  
Productive Infection ◽  
Epifluorescence Microscopy ◽  
Target Cells ◽  
Positive Effects ◽  
Immunodeficiency Virus

ABSTRACT The Nef protein of the type 1 human immunodeficiency virus (HIV-1) plays a key although poorly understood role in accelerating the progression of clinical disease in vivo. Nef exerts several biological effects in vitro, including enhancement of virion infectivity, downregulation of CD4 and major histocompatibility complex class I receptor expression, and modulation of various intracellular signaling pathways. The positive effect of Nef on virion infectivity requires its expression in the producer cell, although its effect is manifested in the subsequent target cell of infection. Prior studies suggest that Nef does not alter viral entry into target cells; nevertheless, it enhances proviral DNA synthesis, arguing for an action of Nef at the level of viral uncoating or reverse transcription. However, these early studies discounting an effect of Nef on virion entry may be confounded by the recent finding that HIV enters cells by both fusion and endocytosis. Using epifluorescence microscopy to monitor green fluorescent protein-Vpr-labeled HIV virion entry into HeLa cells, we find that endocytosis forms a very active pathway for virus uptake. Virions entering via the endocytic pathway do not support productive infection of the host cell, presumably reflecting their inability to escape from the endosomes. Conversely, our studies now demonstrate that HIV Nef significantly enhances CD4- and chemokine receptor-dependent entry of HIV virions into the cytoplasmic compartment of target cells. Mutations in Nef either impairing its ability to downregulate CD4 or disrupting its polyproline helix compromise virion entry into the cytoplasm. We conclude that Nef acts at least in part as a regulator of cytosolic viral entry and that this action contributes to its positive effects on viral infectivity.

scholarly journals Detection of Cell-Cell Fusion Mediated by Ebola Virus Glycoproteins

2006 ◽  
Vol 80 (6) ◽  
pp. 2815-2822 ◽  
Author(s):  
Séverine Bär ◽  
Ayato Takada ◽  
Yoshihiro Kawaoka ◽  
Marc Alizon
Keyword(s):  
Membrane Fusion ◽  
Viral Entry ◽  
Ebola Virus ◽  
Low Ph ◽  
Viral Envelope ◽  
Target Cells ◽  
Direct Role ◽  
Influenza Virus Hemagglutinin ◽  
Ph Dependent

ABSTRACT Ebola viruses (EboV) are enveloped RNA viruses infecting cells by a pH-dependent process mediated by viral glycoproteins (GP) involving endocytosis of virions and their routing into acidic endosomes. As with well-characterized pH-dependent viral entry proteins, in particular influenza virus hemagglutinin, it is thought that EboV GP require activation by low pH in order to mediate fusion of the viral envelope with the membrane of endosomes. However, it has not yet been possible to confirm the direct role of EboV GP in membrane fusion and the requirement for low-pH activation. It was in particular not possible to induce formation of syncytia by exposing cells expressing EboV GP to acidic medium. Here, we have used an assay based on the induction of a β-galactosidase (lacZ) reporter gene in target cells to detect cytoplasmic exchanges, indicating membrane fusion, with cells expressing EboV GP (Zaire species). Acidic activation of GP-expressing cells was required for efficient fusion with target cells. The direct role of EboV GP in this process is indicated by its inhibition by anti-GP antibodies and by the lack of activity of mutant GP normally expressed at the cell surface but defective for virus entry. Fusion was not observed when target cells underwent acidic treatment, for example, when they were placed in coculture with GP-expressing cells before the activation step. This unexpected feature, possibly related to the nature of the EboV receptor, could explain the impossibility of inducing formation of syncytia among GP-expressing cells.

scholarly journals Establishment of a well-characterized SARS-CoV-2 lentiviral pseudovirus neutralization assay using 293T cells with stable expression of ACE2 and TMPRSS2

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0248348
Author(s):  
Sabari Nath Neerukonda ◽  
Russell Vassell ◽  
Rachel Herrup ◽  
Shufeng Liu ◽  
Tony Wang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
293T Cell ◽  
Neutralization Assay ◽  
Target Cells ◽  
Highly Pathogenic ◽  
Angiotensin Converting Enzyme 2 ◽  
Pathogenic Viruses ◽  
Screening Assays ◽  
Assay Precision ◽  
Transmembrane Serine Protease

Pseudoviruses are useful surrogates for highly pathogenic viruses because of their safety, genetic stability, and scalability for screening assays. Many different pseudovirus platforms exist, each with different advantages and limitations. Here we report our efforts to optimize and characterize an HIV-based lentiviral pseudovirus assay for screening neutralizing antibodies for SARS-CoV-2 using a stable 293T cell line expressing human angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). We assessed different target cells, established conditions that generate readouts over at least a two-log range, and confirmed consistent neutralization titers over a range of pseudovirus input. Using reference sera and plasma panels, we evaluated assay precision and showed that our neutralization titers correlate well with results reported in other assays. Overall, our lentiviral assay is relatively simple, scalable, and suitable for a variety of SARS-CoV-2 entry and neutralization screening assays.

scholarly journals The Silent Partners

2020 ◽  
Author(s):  
Gal Almogy
Keyword(s):  
Hospital Admission ◽  
Health Systems ◽  
Emerging Viruses ◽  
Time And Space ◽  
Highly Pathogenic ◽  
Admission Rates ◽  
Current Health ◽  
Rapid Extinction ◽  
Pathogenic Viruses

Despite great advances in understanding the dynamics of viral epidemics, the emergence of rapidly spreading, highly pathogenic viruses remains a realistic and catastrophic possibility, which current health systems may not be able to fully contain. An intriguing feature in many recent zoonotic viral outbreaks is the presence of ‘superspreaders’, which are infected individuals that cause dramatically more new cases than the average. Here I study the effect of superspreaders on the early dynamics of emerging viruses that have not gained the capacity for efficient human-to-human transmission, i.e viruses with R0 < 1. I show that superspreaders have a higher chance of rapid extinction, but under ‘crowded’ conditions can lead to ‘outbreaks’, causing far more cases than regular viruses. Hence I suggest that outbreaks of highly pathogenic superspreaders are more likely when they coincide in time and space with an unrelated outbreak leading to increased hospital admission rates. These superspreader outbreaks may be difficult to detect, especially in the context of a different epidemic in progress, and can significantly affect mortality patterns observed in affected areas.

scholarly journals An Ebola Virus-Like Particle-Based Reporter System Enables Evaluation of Antiviral DrugsIn Vivounder Non-Biosafety Level 4 Conditions

2016 ◽  
Vol 90 (19) ◽  
pp. 8720-8728 ◽  
Author(s):  
Dapeng Li ◽  
Tan Chen ◽  
Yang Hu ◽  
Yu Zhou ◽  
Qingwei Liu ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Viral Entry ◽  
Ebola Virus ◽  
Firefly Luciferase ◽  
Luciferase Reporter ◽  
Target Cells ◽  
Reporter System ◽  
Biosafety Level

ABSTRACTEbola virus (EBOV) is a highly contagious lethal pathogen. As a biosafety level 4 (BSL-4) agent, however, EBOV is restricted to costly BSL-4 laboratories for experimentation, thus significantly impeding the evaluation of EBOV vaccines and drugs. Here, we report an EBOV-like particle (EBOVLP)-based luciferase reporter system that enables the evaluation of anti-EBOV agentsin vitroandin vivooutside BSL-4 facilities. Cotransfection of HEK293T cells with four plasmids encoding the proteins VP40, NP, and GP of EBOV and firefly luciferase (Fluc) resulted in the production of Fluc-containing filamentous particles that morphologically resemble authentic EBOV. The reporter EBOVLP was capable of delivering Fluc into various cultured cells in a GP-dependent manner and was recognized by a conformation-dependent anti-EBOV monoclonal antibody (MAb). Significantly, inoculation of mice with the reporter EBOVLP led to the delivery of Fluc protein into target cells and rapid generation of intense bioluminescence signals that could be blocked by the administration of EBOV neutralizing MAbs. This BSL-4-free reporter system should facilitate high-throughput screening for anti-EBOV drugs targeting viral entry and efficacy testing of candidate vaccines.IMPORTANCEEbola virus (EBOV) researches have been limited to costly biosafety level 4 (BSL-4) facilities due to the lack of animal models independent of BSL-4 laboratories. In this study, we reveal that a firefly luciferase-bearing EBOV-like particle (EBOVLP) with typical filamentous EBOV morphology is capable of delivering the reporter protein into murine target cells bothin vitroandin vivo. Moreover, we demonstrate that the reporter delivery can be inhibited bothin vitroandin vivoby a known anti-EBOV protective monoclonal antibody, 13C6. Our work provides a BSL-4-free system that can facilitate thein vivoevaluation of anti-EBOV antibodies, drugs, and vaccines. The system may also be useful for mechanistic study of the viral entry process.

scholarly journals The Role of the Host Ubiquitin System in Promoting Replication of Emergent Viruses

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 369
Author(s):  
Karl M. Valerdi ◽  
Adam Hage ◽  
Sarah van van Tol ◽  
Ricardo Rajsbaum ◽  
Maria I. Giraldo
Keyword(s):  
Virus Replication ◽  
Defense Mechanism ◽  
Replication Cycle ◽  
Post Translational Modification ◽  
Cellular Functions ◽  
Emerging Viruses ◽  
Highly Pathogenic ◽  
Ubiquitin System ◽  
Pathogenic Viruses

Ubiquitination of proteins is a post-translational modification process with many different cellular functions, including protein stability, immune signaling, antiviral functions and virus replication. While ubiquitination of viral proteins can be used by the host as a defense mechanism by destroying the incoming pathogen, viruses have adapted to take advantage of this cellular process. The ubiquitin system can be hijacked by viruses to enhance various steps of the replication cycle and increase pathogenesis. Emerging viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), flaviviruses like Zika and dengue, as well as highly pathogenic viruses like Ebola and Nipah, have the ability to directly use the ubiquitination process to enhance their viral-replication cycle, and evade immune responses. Some of these mechanisms are conserved among different virus families, especially early during virus entry, providing an opportunity to develop broad-spectrum antivirals. Here, we discuss the mechanisms used by emergent viruses to exploit the host ubiquitin system, with the main focus on the role of ubiquitin in enhancing virus replication.

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