Viruses

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13 pages, 2621 KiB

Open AccessArticle

Structural Investigation of Orf Virus Bcl-2 Homolog ORFV125 Interactions with BH3-Motifs from BH3-Only Proteins Puma and Hrk

by Chathura D. Suraweera, Mark G. Hinds and Marc Kvansakul

Viruses 2021, 13(7), 1374; https://doi.org/10.3390/v13071374 - 15 Jul 2021

Cited by 4 | Viewed by 2374

Abstract

Numerous viruses have evolved sophisticated countermeasures to hijack the early programmed cell death of host cells in response to infection, including the use of proteins homologous in sequence or structure to Bcl-2. Orf virus, a member of the parapoxviridae, encodes for the [...] Read more.

Numerous viruses have evolved sophisticated countermeasures to hijack the early programmed cell death of host cells in response to infection, including the use of proteins homologous in sequence or structure to Bcl-2. Orf virus, a member of the parapoxviridae, encodes for the Bcl-2 homolog ORFV125, a potent inhibitor of Bcl-2-mediated apoptosis in the host. ORFV125 acts by directly engaging host proapoptotic Bcl-2 proteins including Bak and Bax as well as the BH3-only proteins Hrk and Puma. Here, we determined the crystal structures of ORFV125 bound to the BH3 motif of proapoptotic proteins Puma and Hrk. The structures reveal that ORFV125 engages proapoptotic BH3 motif peptides using the canonical ligand binding groove. An Arg located in the structurally equivalent BH1 region of ORFV125 forms an ionic interaction with the conserved Asp in the BH3 motif in a manner that mimics the canonical ionic interaction seen in host Bcl-2:BH3 motif complexes. These findings provide a structural basis for Orf virus-mediated inhibition of host cell apoptosis and reveal the flexibility of virus encoded Bcl-2 proteins to mimic key interactions from endogenous host signalling pathways. Full article

(This article belongs to the Special Issue Voyages through the Multiple Scales of Virus Biology)

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17 pages, 6142 KiB

Open AccessArticle

Light Sheet Microscopy-Assisted 3D Analysis of SARS-CoV-2 Infection in the Respiratory Tract of the Ferret Model

by Luca M. Zaeck, David Scheibner, Julia Sehl, Martin Müller, Donata Hoffmann, Martin Beer, Elsayed M. Abdelwhab, Thomas C. Mettenleiter, Angele Breithaupt and Stefan Finke

Viruses 2021, 13(3), 529; https://doi.org/10.3390/v13030529 - 23 Mar 2021

Cited by 14 | Viewed by 4471

Abstract

The visualization of viral pathogens in infected tissues is an invaluable tool to understand spatial virus distribution, localization, and cell tropism in vivo. Commonly, virus-infected tissues are analyzed using conventional immunohistochemistry in paraffin-embedded thin sections. Here, we demonstrate the utility of volumetric three-dimensional [...] Read more.

The visualization of viral pathogens in infected tissues is an invaluable tool to understand spatial virus distribution, localization, and cell tropism in vivo. Commonly, virus-infected tissues are analyzed using conventional immunohistochemistry in paraffin-embedded thin sections. Here, we demonstrate the utility of volumetric three-dimensional (3D) immunofluorescence imaging using tissue optical clearing and light sheet microscopy to investigate host–pathogen interactions of pandemic SARS-CoV-2 in ferrets at a mesoscopic scale. The superior spatial context of large, intact samples (>150 mm³) allowed detailed quantification of interrelated parameters like focus-to-focus distance or SARS-CoV-2-infected area, facilitating an in-depth description of SARS-CoV-2 infection foci. Accordingly, we could confirm a preferential infection of the ferret upper respiratory tract by SARS-CoV-2 and suggest clustering of infection foci in close proximity. Conclusively, we present a proof-of-concept study for investigating critically important respiratory pathogens in their spatial tissue morphology and demonstrate the first specific 3D visualization of SARS-CoV-2 infection. Full article

(This article belongs to the Special Issue Voyages through the Multiple Scales of Virus Biology)

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Review

Jump to: Research

15 pages, 5084 KiB

Open AccessReview

Imaging of Virus-Infected Cells with Soft X-ray Tomography

by Damià Garriga, Francisco Javier Chichón, Bárbara M. Calisto, Diego S. Ferrero, Pablo Gastaminza, Eva Pereiro and Ana Joaquina Pérez-Berna

Viruses 2021, 13(11), 2109; https://doi.org/10.3390/v13112109 - 20 Oct 2021

Cited by 7 | Viewed by 2582

Abstract

Viruses are obligate parasites that depend on a host cell for replication and survival. Consequently, to fully understand the viral processes involved in infection and replication, it is fundamental to study them in the cellular context. Often, viral infections induce significant changes in [...] Read more.

Viruses are obligate parasites that depend on a host cell for replication and survival. Consequently, to fully understand the viral processes involved in infection and replication, it is fundamental to study them in the cellular context. Often, viral infections induce significant changes in the subcellular organization of the host cell due to the formation of viral factories, alteration of cell cytoskeleton and/or budding of newly formed particles. Accurate 3D mapping of organelle reorganization in infected cells can thus provide valuable information for both basic virus research and antiviral drug development. Among the available techniques for 3D cell imaging, cryo–soft X-ray tomography stands out for its large depth of view (allowing for 10 µm thick biological samples to be imaged without further thinning), its resolution (about 50 nm for tomographies, sufficient to detect viral particles), the minimal requirements for sample manipulation (can be used on frozen, unfixed and unstained whole cells) and the potential to be combined with other techniques (i.e., correlative fluorescence microscopy). In this review we describe the fundamentals of cryo–soft X-ray tomography, its sample requirements, its advantages and its limitations. To highlight the potential of this technique, examples of virus research performed at BL09-MISTRAL beamline in ALBA synchrotron are also presented. Full article

(This article belongs to the Special Issue Voyages through the Multiple Scales of Virus Biology)

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