Transcript Viruses
Viruses I – Structure of viruses Lecture 89 Mgr. M. Jelínek [email protected] Obsah 1) Virus as a entite 2) Introduction to virology 3) Composition of virion 4) Viral replication strategies 1) Viruses are the entities: • Physical – shape, weight, size • Biochemical – consisting of nucleid acids, proteins, phospholipids • Biological • Infectious agens Virus as a biological entite • Intracelullar obligate parasites +/• They have no ribosoms or energetic metabolism either • They have no binar division • They have a genom (RNA or DNA) + • They are affected by biological evolution + • They interact with living organisms +/- 2) Introduction to virology Viruses of procaryots: bacteriofages, cyanofages, mycofages, viruses of protozoans, viruses of plants, animals, Can we use human bacteriophages in medicine? Probably not, but... in ecology, research We can Subviral entities • Viroids Free chains of RNA, can cause deseases, mostly in plants Virusoids – „parasites of virus“, hepatitis D Briefly the history of virology • Babylonia, Antient Greek – knowledge of rabies • Chine – very simple vaccination against small pox • Egypt – hieroglyfs with people with polymyelitis • Breeding of plants • Vaccination – 18. century, England • L. Pasteur, vaccination against rabies virus The 20. century 1892: Dimitrij Ivanovski – tabbaco virus desease 1898: Loeffler a Frosh - foot and mouth disease 1901: Carlos J. Finlay, Colonel W. Reed -virus of yellow fever – building of Panama canal 1911: Peyton Raus - virus and sarkomas 1915, 1917: Twort, dHérelle - bacteriofags 1935: W. Stanley – tabbaco virus desease was observed Importance of virology • Stopping of spreading of dangerous or pandemic incectious diseases • Research of common diseases • New treatment approach – gene therapy, nanotechnologies • Metodical advances in molecular biology • Informations in ecology and evolution biology Important viral infection in the 20. century • • • • Influenza epidemies, most important 1919 Dengue fever, tick born encephalitis Ebola virus Virus HIV, 80´s The origin of viruses regressive theory (viruses developed from cellular parasites) origin in cellular RNA or DNA coevolution of viruses from beggining of life origin in catalytical, autoreplicated RNA molecules Methods of viral investigation • Centrifugation – diferencial centrifugation, ultracentrifugation, electrone microscopy • PCR, elektrophoresis, imunodetection, fluorescence microscopy • Cell cultures, animal models, plaque assays • Epidemiological methods, screening of population 3) Virion Composition of virion: • Nucleid acid (genom) • Capsid • Envelope (only enveloped viruses ) Nucleocapsid –virion, or capsid and genomu for coated viruses http://hiv.boehringer-ingelheim.com/com/HIV/Information_material/Images.jsp Viral nucleid acid = viral genom: RNA/DNA, circular/linear, ss/ds, segmented, nonsegmented Mostly 5 – 50 kb, 5 – 100 genes Genes for • Structural genes – proteins of capsids, glykoproteins of envelope, proteins of matrix • Non – structural genes – enzymes, oncogenes • Non – coding regulatory regions – promotors... • Genes ale often overlapped, are produced at clusters and so on Capsid Capsid is protein- made structure with genom in its inner Composition of capsids: • Identical structural protein units - capsomers. • Capsomere is composed from structure viral proteins Morfology of capsid: Basic types: • ikozahedron consists of 20 triangular areas with 12 peaks (globular proteins) • Helixal complex (viz cytoskelet), filium/bacillus viruses • Cell like viruses • Complicated structures of bacteriofags (head, flagellum, spikes) Převzato z: www.biol.vt.edu Viral envelope • Phosfolipid bilayer with origin in cell membrane • It contains glycoproteins – coded by viruses, they interacts with cell receptor • It contains glycoproteins – coded by viruses, they interacts with cell receptor Properties of viral envelope • Primary potects the genom • It helps to spread the viral genom • Viral and cellular membranes can fused Proteins of viral envelope - antigenes Other components • Virion can contain other proteins – enzymes, cellular proteins, viral chaperons • Proteins used against imunne system • Proteins for latency 4) Replication strategies of viruses • DNA viruses – ssDNA, dsDNA • RNA viruses – ssRNA, ds RNA • Retroviruses – RNA transcribed to DNA and back to RNA • Hepadnaviruses – DNA transcribed to RNA and back to DNA DNA RNA (+)ssRNA (-)ssRNA ssDNA dsRNA Viruses with reverse transcriptase Retroviruses RNA Hepadnaviruses DNA dsDNA HERPESVIRY HEPADNAVIRY dsDNA dsDNA I. VII. RETROVIRY POXVIRY PARVOVIRY ssDNA II. (+)ssRNA Reverzní transkripce VI. dsDNA mRNA (+)ssRNA (–)ssRNA REOVIRY (–)ssRNA ORTHOMYXOVIRY RHABDOVIRY V. dsRNA (+)ssRNA IV. PICORNAVIRY, TOGAVIRY III.