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Introduction: Medical Virology Akram Astani Department of Microbiology University of Yazd

Introduction: Medical Virology Akram Astani Department of Microbiology University of Yazd. VIRUSES?. Basics of Virology. First document of a virus infection. Ruma 1.500 B.C. History of Virology: discovery of viruses.

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Introduction: Medical Virology Akram Astani Department of Microbiology University of Yazd

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  1. Introduction: Medical Virology Akram Astani Department of Microbiology University of Yazd

  2. VIRUSES? Basics of Virology

  3. First document of a virus infection Ruma 1.500 B.C.

  4. History of Virology:discovery of viruses • 1882 A. Mayer: transmission of tobacco mosaic disease by plant extract; pathogen can not be isolated • 1892 D. Ivanofsky: agent of tobacco-mosaic disease is ‚non filtratable‘ and can not be propagated in culture medium • 1898 M. Beijerinck: the pathogen can be propagated in live tissue The pathogen is: ultrafiltratable does not replicate outside of live tissue ultravisible ‚Contagium vivum fluidum‘; later Virus (lat. poison)

  5. History of virology:some important milestones • 1898: Loeffler and Frosch; foot and mouth disease virus (1. animal virus) • 1901: W. Reed; yellow fever virus (first human virus) • 1911: first discovery of a tumor virus (Rous Sarcoma Virus) • 1915: discovery of bacteriophages (Twort; d‘Herelle) • 1935: Crystallization of TMV (Stanley) • 1949: propagation of Polio virus (Enders, Weller, Robbins) • 1970: discovery of reverse Transcriptase (Baltimore, Temin) • 1977: Last case of pox (Somalia) • 1983: discovery of HIV Peyton Rous

  6. Medical importance of viral diseases Leading causes of death in 2008 (World Health Report): Measles: 1.4% (2000)

  7. Viral origin Two theories of viral origin can be summarized as follows: May be derived from DNA or RNA nucleic acid components of host cells may be degenerate forms of intracellular parasites.

  8. Differences between viruses and bacteria con. bacteria rickettsia chlamydia viruses Obligat. Intracell. - + + + Nucleic acid DNA and RNA DNA and RNA DNA and RNA DNA or RNA Protein synthesis + + + - Energy metabolism + + - - Replication cell division cell division cell division Assembly Sensitivity towards antibiotics + + + - CHLAMYDIA: Obligate intracellular bacterial parasite which depends on eucaryotic cell for energy.

  9. ‚Frontiers‘ of Virology Viroid Virosoids Prion genome circular RNA ss RNA - hosts plant plant, human human, animal Example Coconut *Hepatitis D Virus Kuru Cadang Cadang * Need a helper virus (HBV) to replicate

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