Types of Viruses

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Polyhedral virus

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  • Capsid is regular polyhedron with 20 triangular faces (Poliovirus)
  • Nucleic acid packed in the center

Helical Virus

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  • Long Rods
  • Capsid is cylindrical with helical structure (Tobacco Mosaic Virus)
  • Helical nucleocapsid placed within an envelope (Influenza)

Spherical Virus

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  • Roughly spherical
  • Sometimes envelope is covered with spikes (Carbohydrates)
  • Ex: Rice Tungro spherical virus

Function of Capsid/ Envelope

  • Protection
  • Attachment of virus to host cells
  • Introduction of nucleic acid into host cell

Complex Virus

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  • Head - Polyhedral
  • Tail - Helical
  • Icosahedral Shape
  • Found in Bacteriophages
  • Ex: Small pox, Rabies