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Virus Entry

Virus Entry. Steps in virus entry. Penetration through cellular membranes. Intracellular transport. Steps in virus entry. How do virions get into eukaryotic cells? Enveloped and nonenveloped viruses have distinct penetration strategies Some viruses can pass directly from cell to cell.

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Virus Entry

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  1. Virus Entry Steps in virus entry Penetration through cellular membranes Intracellular transport

  2. Steps in virus entry • How do virions get into eukaryotic cells? • Enveloped and nonenveloped viruses have distinct penetration strategies • Some viruses can pass directly from cell to cell

  3. Steps in virus entry Fig. 4.1 Exit and entry of enveloped viruses occurs by vesicle transport.

  4. Steps in virus entry • A variety of cell surface proteins can serve as specific virus receptors Fig. 4.2 Cell surface glycoproteins used as virus receptors.

  5. Steps in virus entry • Receptors interact with viral glycoproteins, surface protrusions, or “canyons” in the surface of the virion • Many viruses enter the cell via receptor-mediated endocytosis

  6. Steps in virus entry • Passage from endosomes to the cytosol is often triggered by low pH

  7. Steps in virus entry • Membrane fusion is mediated by specific viral “fusion proteins” • Fusion proteins undergo major conformational changes that lead to membrane fusion • Nonenveloped viruses penetrate by membrane lysis or pore formation

  8. Steps in virus entry Fig. 4.4 A model for influenza virus hemagglutinin mediated membrane fusion.

  9. Intracellular transport • Virions and capsids are transported within the cell in vesicles or on microtubules • Import of viral genomes into the nucleus • The many ways in which viral genomes are uncoated and released

  10. Intracellular transport • Virions and capsids are transported within the cell in vesicles or on microtubules • Import of viral genomes into the nucleus • The many ways in which viral genomes are uncoated and released

  11. Virus Entry

  12. Amantadine Bafilomycin A1 Budding Carboxylic ionophors Caveolae Caveolin Class I fusion proteins Class II fusion proteins Clathrin-Coated pits Coiled-coil Cytoplasm Cytosol Dynactin Dynein Early endosome Endosome Fission (Membrane) Fusion (Membrane) Fusion peptide Glycolipid Glycoprotein Hemifusion Immunoglobulin family Importin Integrins Karyopherin Ligand Lysosome Lysosomotropic agent Neuraminidase Plasmodesmata Proteoglycan Receptor-mediated endocytosis Sialic acid Syncytium (plural: synctia) Type I transmembrane protein Vesicle transport Key Terms

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