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Virus - Basics & News Taxonomy & Families

Virus - Basics & News Taxonomy & Families. What is a virus ? Structure Genome Replication. A virus is a virus ( lat: poison ). Replication: a replicating biochemical complex without its own metabolism requires metabolism of living host cell for replication

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Virus - Basics & News Taxonomy & Families

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  1. Virus - Basics & NewsTaxonomy & Families What is a virus ? Structure Genome Replication

  2. A virus is a virus (lat: poison) • Replication: a replicating biochemical complex without its own metabolism • requires metabolism of living host cellfor replication • Structure: Submicroscopic Size, 30 - 150 nm • (exception:orthopox) • Genome: contains genetic information, DNA or RNA

  3. Virus - sizes

  4. Comparison of Size: Virus/Bakterium

  5. An infectious virus particle ‘Virion‘ • The genome (DNA or RNA) is always packed in a protein structure the ‘Capsid‘ • The combine Capsid/Genomestructure: ‘Nukleocapsid‘ • The capsid structure can be spherical (Icosaeder) or helical structure (Tubulus) • Some viruses have additional structures: a lipid envelope • engulfing the capsid

  6. non enveloped Virus: contains only nucleic acid and protein Tobacco mosaic virus: helical capsid Adenovirus: icosahedral capsid

  7. ‘enveloped viruses‘ Herpes Simplex Virus Paramyxovirus For enveloped viruses, the lipid envelope is always essential for infectivity. The envelops can be easily destoyed by ether & detergents

  8. Spherical capsids have an icosahedral structure • An Icosahedron has 20 triangular surfaces and three axes of symmetry Picornavirus: 5-fold axes of smmetry animated X-Ray structure

  9. Icosahedral capsids are built from capsomers: identical units of the same proteins X-Ray structure capsid of picornaviridae

  10. The capsid surface of non enveloped viruse must carry structures for binding to cellular receptors These both (non related) viruses bind to CAR but the binding structures look very different ‘Canyons‘ for binding to CAR (many enterovirus types) Fiber (‘Spikes‘) for bindingto CAR (many adenovirustypes)

  11. Comparison:replication of virus vs. bacterium • obligat intrazellulär • NIE auf Nährmedien, Agars usw. • lebende Zellen erforderlich: • Versuchstier • Brutei • Zellkultur • Eklipse bzw. Latenzperiode, • Adsorption, Penetration, Uncoating • Proteinsynthese & Genomreplikation • Assembly & Virusfreisetzung

  12. Classical Concept of ICTV • taxonomy system: family/genus/species • family names: ...-idae • relevant for virus family: • genome type (DNA, RNA; ds-, ss-, ) • capsid structure (helical, icosahedral) • enveloped/non enveloped

  13. RNA viruses RNA-Virus

  14. DNA viruses DNA-Virus

  15. Baltimore Systemway of mRNA production (->Proteinsynthesis) DNA Virus RNA Virus

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