scholarly journals Cellular Electron Cryo-Tomography to Study Virus-Host Interactions

2020 ◽  
Vol 7 (1) ◽  
pp. 239-262
Author(s):  
Emmanuelle R.J. Quemin ◽  
Emily A. Machala ◽  
Benjamin Vollmer ◽  
Vojtěch Pražák ◽  
Daven Vasishtan ◽  
...  
Keyword(s):  
Viral Entry ◽  
Cell Biology ◽  
Molecular Mechanisms ◽  
Virus Assembly ◽  
Three Dimensional ◽  
Surface Proteins ◽  
Host Cells ◽  
Phase Plate ◽  
Structural Cell ◽  
Host Interactions

Viruses are obligatory intracellular parasites that reprogram host cells upon infection to produce viral progeny. Here, we review recent structural insights into virus-host interactions in bacteria, archaea, and eukaryotes unveiled by cellular electron cryo-tomography (cryoET). This advanced three-dimensional imaging technique of vitreous samples in near-native state has matured over the past two decades and proven powerful in revealing molecular mechanisms underlying viral replication. Initial studies were restricted to cell peripheries and typically focused on early infection steps, analyzing surface proteins and viral entry. Recent developments including cryo-thinning techniques, phase-plate imaging, and correlative approaches have been instrumental in also targeting rare events inside infected cells. When combined with advances in dedicated image analyses and processing methods, details of virus assembly and egress at (sub)nanometer resolution were uncovered. Altogether, we provide a historical and technical perspective and discuss future directions and impacts of cryoET for integrative structural cell biology analyses of viruses.

scholarly journals Optical nanoscopy reveals SARS-CoV-2-induced remodeling of human airway cells

2021 ◽  
Author(s):  
Wilco Nijenhuis ◽  
Hugo G.J. Damstra ◽  
Emma J. van Grinsven ◽  
Malina K. Iwanski ◽  
Patrique Praest ◽  
...  
Keyword(s):  
Viral Entry ◽  
Three Dimensional ◽  
Host Cells ◽  
Apical Surface ◽  
Ciliated Cells ◽  
Host Interactions ◽  
Human Airway ◽  
Cell Remodeling ◽  
Key Aspects ◽  
Airway Cells

A better understanding of host cell remodeling by the coronavirus SARS-CoV-2 is urgently needed to understand viral pathogenesis and guide drug development. Expression profiling and electron microscopy have frequently been used to study virus-host interactions, but these techniques do not readily enable spatial, sub-cellular and molecular analysis of specific cellular compartments. Here, we use diffraction-unlimited fluorescence microscopy to analyze how SARS-CoV-2 infection exploits and repurposes the subcellular architecture of primary human airway cells. Using STED nanoscopy, we detect viral entry factors along the motile cilia of ciliated cells and visualize key aspects of the viral life cycle. Using Tenfold Robust Expansion (TREx) microscopy, we analyze the extensively remodeled three-dimensional ultrastructure of SARS-CoV-2-infected ciliated cells and uncover Golgi fragmentation, emergence of large and atypical multivesicular bodies enclosing viral proteins, ciliary clustering, and remodeling of the apical surface. These results demonstrate a broadly applicable strategy to study how viruses reorganize host cells with spatial and molecular specificity and provide new insights into SARS-CoV-2 infection in primary human cell models.

scholarly journals An endometrial organoid model of Chlamydia-epithelial and immune cell interactions

2020 ◽  
Author(s):  
Lee Dolat ◽  
Raphael H. Valdivia
Keyword(s):  
Epithelial Cell ◽  
Cell Biology ◽  
Immune Cell ◽  
Three Dimensional ◽  
Time Lapse ◽  
Cell Types ◽  
Infection Process ◽  
Host Cells ◽  
Cell Diversity ◽  
Intracellular Organelles

ABSTRACTOur understanding of how the obligate intracellular bacterium Chlamydia trachomatis reprograms the cell biology of host cells in the upper genital tract is largely based on observations made in cell culture with transformed epithelial cell lines. Here we describe a primary spherical organoid system derived from endometrial tissue to recapitulate epithelial cell diversity, polarity, and ensuing responses to Chlamydia infection. Using high-resolution and time-lapse microscopy, we catalogue the infection process in organoids from invasion to egress, including the reorganization of the cytoskeleton and positioning of intracellular organelles. We show this model is amenable to screening C. trachomatis mutants for defects in the fusion of pathogenic vacuoles, the recruitment of intracellular organelles, and inhibition of cell death. Moreover, we reconstructed a primary immune cell response by co-culturing infected organoids with neutrophils, and determined that the effector TepP limits the recruitment of neutrophils to infected organoids. Collectively, our model details a system to study the cell biology of Chlamydia infections in three dimensional structures that better reflect the diversity of cell types and polarity encountered by Chlamydia upon infection of their animal hosts.Summary statement3D endometrial organoids to model Chlamydia infection and the role of secreted virulence factors in reprogramming host epithelial cells and immune cell recruitment

scholarly journals MicroRNAs and Mammarenaviruses: Modulating Cellular Metabolism

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2525
Author(s):  
Jorlan Fernandes ◽  
Renan Lyra Miranda ◽  
Elba Regina Sampaio de Lemos ◽  
Alexandro Guterres
Keyword(s):  
Metabolic Pathways ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
Mirna Expression Profile ◽  
Metabolic Reprogramming ◽  
Host Cells ◽  
Emerging Viruses ◽  
Cellular Mirnas ◽  
Host Interactions ◽  
Causative Agents

Mammarenaviruses are a diverse genus of emerging viruses that include several causative agents of severe viral hemorrhagic fevers with high mortality in humans. Although these viruses share many similarities, important differences with regard to pathogenicity, type of immune response, and molecular mechanisms during virus infection are different between and within New World and Old World viral infections. Viruses rely exclusively on the host cellular machinery to translate their genome, and therefore to replicate and propagate. miRNAs are the crucial factor in diverse biological processes such as antiviral defense, oncogenesis, and cell development. The viral infection can exert a profound impact on the cellular miRNA expression profile, and numerous RNA viruses have been reported to interact directly with cellular miRNAs and/or to use these miRNAs to augment their replication potential. Our present study indicates that mammarenavirus infection induces metabolic reprogramming of host cells, probably manipulating cellular microRNAs. A number of metabolic pathways, including valine, leucine, and isoleucine biosynthesis, d-Glutamine and d-glutamate metabolism, thiamine metabolism, and pools of several amino acids were impacted by the predicted miRNAs that would no longer regulate these pathways. A deeper understanding of mechanisms by which mammarenaviruses handle these signaling pathways is critical for understanding the virus/host interactions and potential diagnostic and therapeutic targets, through the inhibition of specific pathologic metabolic pathways.

scholarly journals Sulfated Glycans and Related Digestive Enzymes in the Zika Virus Infectivity: Potential Mechanisms of Virus-Host Interaction and Perspectives in Drug Discovery

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Vitor H. Pomin
Keyword(s):  
Neural Development ◽  
Zika Virus ◽  
Molecular Mechanisms ◽  
Surface Proteins ◽  
Host Cells ◽  
Future Research ◽  
Virus Infectivity ◽  
Virus Attachment ◽  
Chemical Structures ◽  
Host Interaction

As broadly reported, there is an ongoing Zika virus (ZIKV) outbreak in countries of Latin America. Recent findings have demonstrated that ZIKV causes severe defects on the neural development in fetuses in utero and newborns. Very little is known about the molecular mechanisms involved in the ZIKV infectivity. Potential therapeutic agents are also under investigation. In this report, the possible mechanisms of action played by glycosaminoglycans (GAGs) displayed at the surface proteoglycans of host cells, and likely in charge of interactions with surface proteins of the ZIKV, are highlighted. As is common for the most viruses, these sulfated glycans serve as receptors for virus attachment onto the host cells and consequential entry during infection. The applications of (1) exogenous sulfated glycans of different origins and chemical structures capable of competing with the virus attachment receptors (supposedly GAGs) and (2) GAG-degrading enzymes able to digest the virus attachment receptors on the cells may be therapeutically beneficial as anti-ZIKV. This communication attempts, therefore, to offer some guidance for the future research programs aimed to unveil the molecular mechanisms underlying the ZIKV infectivity and to develop therapeutics capable of decreasing the devastating consequences caused by ZIKV outbreak in the Americas.

scholarly journals Probing Molecular Insights of Zika Virus-Host Interactions

2018 ◽  
Author(s):  
Ina Lee ◽  
Sandra Bos ◽  
Ge Li ◽  
Shusheng Wang ◽  
Gilles Gadea ◽  
...  
Keyword(s):  
Viral Entry ◽  
Zika Virus ◽  
Protein Structures ◽  
Fetal Brain ◽  
Protein S ◽  
Cell Receptor ◽  
Host Cells ◽  
Host Interactions ◽  
Neurologic Disorders ◽  
Viral Virulence

The recent Zika virus (ZIKV) outbreak in Americas surprised all of us because of its rapid spread and association with neurologic disorders including fetal microcephaly, brain and ocular anomalies and Guillain-Barré syndrome. In responding to this global health outcry, unprecedented and world-wide efforts are taking place to study the ZIKV etiology. Much have been learned about this virus in the areas of epidemiology, clinical manifestation, viral sequences and protein structures, as well as effects of ZIKV infection on fetal brain development and microcephaly. However, the molecular mechanism underlying ZIKV-mediated neurologic disorders remains elusive. Some critical questions include: 1) what type of virologic changes has taken place that increased the viral virulence? 2) which ZIKV protein(s) is responsible for the enhanced viral pathogenicity? And 3) how the newly adapted and pathogenic ZIKV strains alter their interactions with host cells leading to neurologic disorders? The goal of this review is to explore the molecular insights into the ZIKV-host interactions with special focuses on host cell receptor usage for viral entry, host cellular and immune antiviral responses, ZIKV counteraction and ZIKV-induced cytopathic effects. Our hope with this literature review is to inspire additional studies focusing on molecular studies of ZIKV-host Interactions.

scholarly journals Electron tomography of cells

2011 ◽  
Vol 45 (1) ◽  
pp. 27-56 ◽  
Author(s):  
Lu Gan ◽  
Grant J. Jensen
Keyword(s):  
Electron Microscope ◽  
Cell Biology ◽  
3D Imaging ◽  
Imaging Technique ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Molecular Organization ◽  
Biological Structure ◽  
Structural Cell ◽  
Projection Images

AbstractThe electron microscope has contributed deep insights into biological structure since its invention nearly 80 years ago. Advances in instrumentation and methodology in recent decades have now enabled electron tomography to become the highest resolution three-dimensional (3D) imaging technique available for unique objects such as cells. Cells can be imaged either plastic-embedded or frozen-hydrated. Then the series of projection images are aligned and back-projected to generate a 3D reconstruction or ‘tomogram’. Here, we review how electron tomography has begun to reveal the molecular organization of cells and how the existing and upcoming technologies promise even greater insights into structural cell biology.

scholarly journals Identification of Residues Controlling Restriction versus Enhancing Activities of IFITM Proteins on Entry of Human Coronaviruses

2017 ◽  
Vol 92 (6) ◽  
Author(s):  
Xuesen Zhao ◽  
Mohit Sehgal ◽  
Zhifei Hou ◽  
Junjun Cheng ◽  
Sainan Shu ◽  
...  
Keyword(s):  
Aspartic Acid ◽  
Viral Entry ◽  
Molecular Mechanisms ◽  
Biological Activities ◽  
Viral Envelope ◽  
Host Factors ◽  
Host Cells ◽  
Restriction Factors ◽  
Structural Motifs ◽  
Infectious Entry

ABSTRACTInterferon-induced transmembrane proteins (IFITMs) are restriction factors that inhibit the infectious entry of many enveloped RNA viruses. However, we demonstrated previously that human IFITM2 and IFITM3 are essential host factors facilitating the entry of human coronavirus (HCoV) OC43. In a continuing effort to decipher the molecular mechanism underlying IFITM differential modulation of HCoV entry, we investigated the roles of structural motifs important for IFITM protein posttranslational modifications, intracellular trafficking, and oligomerization in modulating the entry of five HCoVs. We found that three distinct mutations in IFITM1 or IFITM3 converted the host restriction factors to enhance entry driven by the spike proteins of severe acute respiratory syndrome coronavirus (SARS-CoV) and/or Middle East respiratory syndrome coronavirus (MERS-CoV). First, replacement of IFITM3 tyrosine 20 with either alanine or aspartic acid to mimic unphosphorylated or phosphorylated IFITM3 reduced its activity to inhibit the entry of HCoV-NL63 and -229E but enhanced the entry of SARS-CoV and MERS-CoV. Second, replacement of IFITM3 tyrosine 99 with either alanine or aspartic acid reduced its activity to inhibit the entry of HCoV-NL63 and SARS-CoV but promoted the entry of MERS-CoV. Third, deletion of the carboxyl-terminal 12 amino acid residues from IFITM1 enhanced the entry of MERS-CoV and HCoV-OC43. These findings suggest that these residues and structural motifs of IFITM proteins are key determinants for modulating the entry of HCoVs, most likely through interaction with viral and/or host cellular components at the site of viral entry to modulate the fusion of viral envelope and cellular membranes.IMPORTANCEThe differential effects of IFITM proteins on the entry of HCoVs that utilize divergent entry pathways and membrane fusion mechanisms even when using the same receptor make the HCoVs a valuable system for comparative investigation of the molecular mechanisms underlying IFITM restriction or promotion of virus entry into host cells. Identification of three distinct mutations that converted IFITM1 or IFITM3 from inhibitors to enhancers of MERS-CoV or SARS-CoV spike protein-mediated entry revealed key structural motifs or residues determining the biological activities of IFITM proteins. These findings have thus paved the way for further identification of viral and host factors that interact with those structural motifs of IFITM proteins to differentially modulate the infectious entry of HCoVs.

Two repetitive, biofilm-forming proteins from Staphylococci: from disorder to extension

2015 ◽  
Vol 43 (5) ◽  
pp. 861-866 ◽  
Author(s):  
Fiona Whelan ◽  
Jennifer R. Potts
Keyword(s):  
Medical Device ◽  
Staphylococcus Epidermidis ◽  
Molecular Mechanisms ◽  
Surface Proteins ◽  
Initial Surface ◽  
Surface Attachment ◽  
Bacterial Surface ◽  
Host Interactions ◽  
And Function

Staphylococcus aureus and Staphylococcus epidermidis are an important cause of medical device-related infections that are difficult to treat with antibiotics. Biofilms, in which bacteria are embedded in a bacterially-produced exopolymeric matrix, form on the surface of the implanted medical device. Our understanding of the molecular mechanisms underlying the initial surface attachment and subsequent intercellular interactions as the biofilm matures is improving. Biofilm accumulation can be mediated by a partially deacetylated form of poly-N-acetylglucosamine (PNAG) but, more recently, the role of bacterial surface proteins is being recognized. Here we describe the structure and function of two S. aureus cell surface proteins, FnBPA and SasG, implicated in host interactions and biofilm accumulation. These multifunctional proteins employ intrinsic disorder for distinct molecular outcomes. In the case of FnBPA, disorder generates adhesive arrays that bind fibronectin (Fn); in the case of SasG, disorder is, counterintuitively, used to maintain a strong extended fold.

scholarly journals Histopathological features of SARS-CoV-2 infection and relationships with organoid technology

2021 ◽  
Vol 49 (9) ◽  
pp. 030006052110443
Author(s):  
İrem İnanç ◽  
Esra Erdemli
Keyword(s):  
Viral Entry ◽  
Three Dimensional ◽  
Human Cells ◽  
Host Cells ◽  
Angiotensin Converting Enzyme 2 ◽  
Antiviral Compounds ◽  
Global Pandemic ◽  
Species Specific

Coronavirus disease 2019 (COVID-19) following infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused a global pandemic that is still having serious effects worldwide. This virus, which targets the lungs in particular, can also damage other tissues. Angiotensin converting enzyme 2 (ACE-2) plays a key role in viral entry into host cells. The presence of ACE-2 in various tissues may permit viral infection. Studies of COVID-19 often make use of postmortem tissues. Although this information provides various useful results, it is also necessary to conduct in vitro studies to understand optimal treatment approaches. Because the virus may show species-specific differences, in vitro technologies using human cells are particularly important. Organoid technologies, three-dimensional structures that can be obtained from human cells, are playing increasingly important roles in studies of SARS-CoV-2. This technology offers a significant advantage in terms of mimicking in vivo tissue structures and testing antiviral compounds. In this mini-review, we summarize studies of SARS-CoV-2 using both histopathological and organoid technology approaches.

Application of low-voltage, high-resolution SEM in the study of complex intracellular structures

1990 ◽  
Vol 48 (3) ◽  
pp. 18-19
Author(s):  
Hans Ris
Keyword(s):  
High Resolution ◽  
Cell Biology ◽  
Low Voltage ◽  
Three Dimensional ◽  
Nuclear Pore ◽  
Structural Cell ◽  
Macromolecular Assemblies ◽  
New Information ◽  
A Cell ◽  
Ultrathin Sections

Cellular architecture is a dynamic web of complex macromolecular assemblies accomplishing the diverse functions of a cell. Conventional electron microscopy on ultrathin sections or negatively stained preparations can provide little information on more extended three dimensional assemblies. High voltage and intermediate voltage TEM provide high resolution in much thicker specimens but are limited by problems of contrast and overlap of structures. In recent years new SEMs have become available that provide the high topographic contrast and three dimensionality of SEM at a resolution comparable to conventional TEM. I have used the low voltage high resolution SEM Hitachi S-900 at the Madison IMR and shall show some examples that illustrate the usefulness of LVSEM in structural cell biology. Most striking is the new information obtained about the nuclear pore complex (NPC). This structure is extremely important in controlling the selective and unidirectional transport of large molecules into and out of the nucleus.

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