viruses i – structure of viruses lecture 89 mgr. m. jelínek [email protected]
TRANSCRIPT
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Obsah
1) Virus as a entite
2) Introduction to virology
3) Composition of virion
4) Viral replication strategies
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1) Viruses are the entities:
• Physical – shape, weight, size
• Biochemical – consisting of nucleid acids, proteins, phospholipids
• Biological
• Infectious agens
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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 +/-
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2) Introduction to virology
Viruses of procaryots: bacteriofages, cyanofages, mycofages, viruses of protozoans, viruses of plants, animals, human Can we use
bacteriophages in medicine?
Probably not, but...
in ecology, research
We can
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Subviral entities
• Viroids
Free chains of RNA, can cause deseases, mostly in plants
Virusoids – „parasites of virus“, hepatitis D
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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
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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
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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
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Important viral infection in the 20. century
• Influenza epidemies, most important 1919
• Dengue fever, tick born encephalitis
• Ebola virus
• Virus HIV, 80´s
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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
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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
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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
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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
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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
Capsid
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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)
Morfology of capsid:
Převzato z: www.biol.vt.edu
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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
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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
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Other components
• Virion can contain other proteins – enzymes, cellular proteins, viral chaperons
• Proteins used against imunne system
• Proteins for latency
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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
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RNA
(+)ssRNA (-)ssRNA dsRNA
DNA
ssDNA dsDNA
Viruses with reverse transcriptase
RetrovirusesRNA
Hepadnaviruses DNA
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mRNAmRNA
dsDNA
HERPESVIRY
POXVIRY
I.I. ssDNA
II.II.
PARVOVIRY
dsDNA
dsRNA
III.III.
REOVIRY
IV.IV.(+)ssRNAPICORNAVIRY, TOGAVIRY
(–)ssRNA
(–)ssRNA
(+)ssRNA
V.V.ORTHOMYXOVIRYRHABDOVIRY
(+)ssRNARETROVIRY
Reverzní transkripceVI.VI.
dsDNAHEPADNAVIRY
VII.VII.