Medical Microbiology, Jawetz (????? ???)

1

• Medical Microbiology, Jawetz (????? ???)
• 2) Medical Microbiology , Murray , 1998
•   (????? ??? ) 3) Zinssser microbiology
•  

2
Introduction to Virology

• Viruses are intracellular obligate parasites
  which means that they cannot replicate or express
  their genes without the help of a living cell.
• When a virus infects a cell, it marshals the
  cell's ribosomes, enzymes and much of the
  cellular machinery to replicate.
• Virus particles can only be
  observed by an electron microscope.

3
Introduction to Virology

• The classification of viruses is based on the
  type of nucleic acid contained within
• RNA viruses---also known as a retrovirus
• DNA viruses

4
Introduction to Virology

• Recognizing the shape, size, and structure of
  different viruses is critical to the study of
  disease.
• virion,  an entire virus particle, consisting of
  an outer protein shell called a capsid and an
  inner core of nucleic acid
• Some viruses are surrounded by protein coat known
  as an envelope.
• The core is responsible for infectivity and the
  capsid provides specificity to the virus.
• Most viruses have sizes of 20250 nanometers

5
Introduction to Virology

• Replication
• Viruses replicate within a host cell while
  utilizing the host cells nucleic acids.

6
Introduction to Virology

• Viral life cycle consists of six stages within
  the host cell
• Attachment virus binds to the host cell.
• Penetration virus injects its genome into host
  cell.
• Uncoating
• Multiplication
• viral genome replicates using the host's cellular
  machinery
• Assembly viral components and enzymes are
  produced and begin to assemble
• Release newly produced viruses are expelled from
  the host cell

7
Introduction to Virology

• The cultivation of viruses is complex and
  includes three common methods
• Chicken egg culture
• Cell culture
• Animal inoculation

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Introduction to Virology

• Viral Diseases-Examples
• Influenza
• HIV or AIDS
• Hepatitis
• Smallpox
• rabies virus
• Sever Acute Respiratory Syndrome (SARS)

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Virus capsid

• Very tiny particle of matter composed of a core
  of nucleic acid and a covering of protein that
  protects the virus

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Viruses

• Have characteristics of both living and nonliving
  material
• Are on the borderline between living and non
  living

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Viruses

• Made up of some of the material found in cells
  but are not cells because they do not have a
  nucleus or other cell parts.

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Viruses

• Do not grow and cannot reproduce outside a living
  cell
• Once inside a living cell, virus reproduces using
  energy and materials in the invaded cell

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Viruses

• Harm cells during reproduction
• And by using material that the cell needs to
  function properly

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Virus

• Viral diseases cause the animal to be sick by
  preventing certain cells in the body from
  functioning properly

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Virus

• More difficult to treat than bacterial diseases
• Antibiotics are not effective against viral
  infections

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Viral diseases

• Best means of dealing with them is prevention

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General Virology
VIRUS STRUCTURE
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Virion

• Virion is the infectious particle
• composed of nucleic acid, protein capsid, /-
  envelope
• may be extracellular or intracellular

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Capsid

• Functions
• Protection of NA
• Attachment
• Helical vs Icosahedral Symmetry -
• Tobacco mosaic virus is a ssRNA virus composed of
  6000 nucleotides. The capsid is made of 2100
  copies of a single protein subunit that contain
  158 amino acids.

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How do helical viruses differ?

• Helical- one axis of symmetry down center
• Multiple structural units

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Icosahedral symmetry

• 20 identical equilateral triangles
• Structural units on faces to give morphological
  capsomers
• Pentons (5 fold axis of symmetry)
• Hexons
• 3 fold through face
• 2 fold through edge

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Envelope

• Attachment
• Entry
• Assembly- matrix proteins
• Release
• Proteins are viral
• Lipids are host
• Rare in plants or bacteria

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VIRUS GENOMES
DNA
RNA
Single Stranded
or -
Double Stranded
Segmented
Double Stranded Segmented
Circular
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HELICAL ICOSAHEDRAL
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DNA VIRUSES
PARVOVIRIDAE
POLYOMAVIRIDAE
ADENOVIRIDAE
HERPESVIRIDAE
HEPADNAVIRIDAE
POXVIRIDAE
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RNA VIRUSES
TOGAVIRIDAE
FLAVIVIRIDAE
BUNYAVIRIDAE
REOVIRIDAE
PICORNAVIRIDAE
RHABDOVIRIDAE
ARENAVIRIDAE
CORONAVIRIDAE
PARAMYXOVIRIDAE
ORTHOMYXOVIRIDAE
RETROVIRIDAE
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34
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35

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36
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37
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39
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40

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41

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• ?? ??? ???? ???? ??????? ?? 2 ??????? ???? ??
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• ?????? ? ????????? ? ???? ?? ??? ???? ??????
  Naked ?? Enveloped
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  ???????.

42

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• ?????? ?????? ?? ????? ?????.
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43
. ???? ????? ??? DNA ??? ???? ????? ?? ?????
DNA ?? ??????? ????? ? ?? ???????? ??????? ?????
??? ????? ????. ???? ????? ?? ????????? ?? DNA
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????? ?? ????????? ????? ?? DNA ? ?? ???????.
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44
???? ????? ??? RNA???? ??? ????? ?? ????????
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????? ???? ????? ??? RNA????

• ????? ????? ?? ????? RNA ?? ??????? ????? ? ????
  ?????? ?? ???????? ?????? ????? ????????.
• ??????? ????? ?? ????? ???? ?? RNA ?? ???????
  ?????. ?? ???? ???????? ??? ???? ??? ????? ?
  ?????? A ?? ??? ???? ???? ?????.
• ???? ????? ?? ????? RNA ?? ??????? ????? ?
  ???????? ???? ???? ?? ??????? ?? ??? ???? ????
  ????.
• ???? ????? ?? ??? ??????? ????? RNA ?? ???? ??
  ?????? ?????? ??? ????? ????? ?????? ? ???? ??
  ??? ?? ??? ???? ???? ????.

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???????

• ???? ??????? ???? ???? ?? ??????? ?? mRNA ?????
  ????? ? ???????????? ?????? ?? ????.
• ???mRNA ?? ??????? ???? ????? ??? ? ??????? ???
  ???? ???? ???? ????? ?? ??? ??????? ???? ?????
  ???? ??????? ??? ?????????? ?????? ?? ???.

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Segmented RNA

• ???? ?? ????? ?? ????? ???? ???? ???? ????? ?? ??
  ???? ?? ????? ??? ????? ??? ?? ???.
• ????? ???? ????? ??? ????? ????? ??? ?????????
  ????? ??? ??? ????? ??? ???? ????? ?? ? ????
  ????? ??

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???????

• ??? RNA ????? ?? ????? mRNA ??? ??? ? ???????
  ???? ??????? ?? ????? ??? RNA ?? ??????? ????
  ?????? ?? ???.
• ????? ???? ?? RNA ??????? ?????? ?? RNA ?? ?? ???
  ??? ?? ???? ????? RNA ?? ??????? ???? ?????.(????
  ??? ?????????? ???? RNA ??????? ?????.)