Reoviridae

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Reoviridae
Reoviruses Respiratory Enteric Orphan
virus three serotypes that infect man (types
1, 2, 3) usually mild upper respiratory
disease found world-wide Rotaviruses Three
serotypes cause widespread illness in man Groups
A, B, C Significant agents for diarrheal
illnesses Orbiviruses Most infect vertebrates
other than man but Changuinola virus causes
disease in humans Coltiviruses Colorado tick
fever virus causes human disease
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Reovirus Properties

• Particles
• Spherical, with icosahedral (532) symmetry
• Nonenveloped
• Total diameter 85 nm (excluding s1 fibers)
• Two concentric protein capsids outer capsid
  subunits in T13 lattice, arrangement of inner
  capsid subunits unknown
• 8 structural proteins 4 proteins in outer capsid
  (l2, m1 mostly as cleavage fragments m1N and
  m1C, s1, and s3) and 4 proteins in inner capsid
  (l1, l3, m2, and s2)
• Subviral particles (ISVPs and cores) can be
  generated from fully intact particles (virions)
  by controlled proteolysis.
• Cell-attachment protein s1 can extend from the
  virion and ISVP surface as a long fiber.
• Protein l2 forms pentamers that protrude from the
  core surface.

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Reovirus Structure
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Reovirus Properties

• Genome
• Double-stranded RNA
• 10 gene segments in three size classes (L, M, S)
• Total size 23,500 base pairs
• Gene segments encode either one or two proteins
  each.
• Gene segments are transcribed into full-length
  mRNAs.
• Plus strands of gene segments have 5' caps.
• Nontranslated regions at segment termini are
  short.
• Gene segments can undergo reassortment between
  virus strains.

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B
A
l2
s2
l3 RNA pol
l1
m2
C
D
() ssRNA
5 cap
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