Host cytoskeleton and membrane network remodeling in the regulation of viral replication

Figures

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  Figure 1. Morphology and assembly of the cytoskeleton. A Cellular distribution of actin filaments, microtubules, and intermediate filaments. B G-actin monomer is gradually assembled into F-actin. C The monomers of intermediate filaments are gradually assembled into a tetramer, unit-length filament (ULF) and mature filament. D α- and β-tubulin monomers are dimerized to form tubulin heterodimer, which then is assembled into hollow tubular structures with a diameter of about 25 nm

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  Figure 2. Types of viral factory. According to the differences in morphology and structure, cytoplasmic viral factories can be divided into four categories, including viroplasm, spherule, DMV and tube. Spherules can originate from mitochondria, peroxisome, chloroplast, endosome and endoplasmic reticulum. DMVs originate from the endoplasmic reticulum, and tubes originate from Golgi. Nuclear viral factories exist in the dorsal side of cellular nucleus

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  Figure 3. Spherical viral factories originating from the endoplasmic reticulum. A Schematic representation of the Flavivirus (ZIKV, DENV) replication and assembly compartments. Genome replication occurs within VPs formed upon ER membrane invagination. Vi: virions. B Electron tomography of ZIKV-induced VPs in hNPCs. A slice through a tomogram is shown depicting ZIKV-induced vesicles (Ve) within the rough ER as well as Vi. Scale bar: 100 nm (adapted from ref. (Cortese et al. 2017) with copyright permission from Creative Commons license). C Slice through the tomogram showing the pore-like openings (colored arrowheads) of ZIKV induced vesicles toward the cytoplasm. A potential ZIKV budding event (Vi) on the ER tubule opposing the vesicle pore can be observed. Scale bar: 100 nm (adapted from ref. (Cortese et al. 2017) with copyright permission from Creative Commons license). D Schematic representation of DMVs formed by ER protrusions. Typical viruses include HCV, MERS-CoV, SARS-CoV-1, SARS-CoV-2. DMVs are responsible for viral genome replication. E Tomogram showing DMVs in VeroE6 cells infected with SARS-CoV-2 at 16 hpi. Scale bar: 100 nm (adapted from ref. (Klein et al. 2020) with copyright…

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  Figure 4. Viral infection induces cytoskeleton remodeling into cage-like structure. Virus infection can cause severe rearrangement of the cytoskeleton, and all three kinds of cytoskeleton form a cage-like structure enclosing the near-nuclear virus factory. Microfilaments form actin ring around the virus components, endoplasmic reticulum, Golgi apparatus, etc.; intermediate filaments form an intermediate filament cage to completely wrap the virus factory; microtubules form a grid shape microtubule cage