630 Microbiology for Teachers

Viruses

General Characteristics

• Morphology 

   

  • Nucleocapsid
    • nucleic acid 

   

  • capsid 

   

  • Envelope
    • membrane derived from host cell 

   

  • only certain animal viruses have envelopes 

   

• Physiology 

   

• Reproduction 

   

  • Attachment 

   

  • Penetration

   

  • Uncoating

   

  • Biosynthesis

   

  • Maturation

   

  • Release

   

• Importance and Habitat

   

Groups of Viruses

• Bacterial Viruses (Bacteriophages) - consequences of virus infection of a bacterial host cell include:
  • Lytic Infection - bacteriophage replication cycle
    • Attachment

   

  • Penetration and uncoating

   

  • Synthesis

   

  • Assembly

   

  • Release

   

  • Lysogeny
    • Bacteriophage DNA integrates into the host chromosome

   

  • No progeny virions are made

   

• Animal Viruses - consequences of virus infection of a animal host cell include:
  • Lytic infection

   

  • Attachment

   

  • Penetration

   

  • Enveloped viruses

   

  • Nonenveloped viruses

   

  • Uncoating

   

  • Synthesis

   

   

  • Assembly

   

  • Release

   

  • Persistent infection

   

  • Latent infection

   

  • Transformation

   

  • benign tumor

   

  • malignant tumor

   

• Plant Viruses - consequences of virus infection of a plant host cell include:
  • Similar in most respects to those seen for animal cells

   

  • Penetration is more difficult

   

Virus Classification by Genome and Physical Characteristics

• DNA Viruses
  • ds DNA
    • enveloped
      • Baculoviridae

   

  • Herpesviridae

   

  • Iridoviridae

   

  • Poxviridae

   

  • African Swine Fever Viruses

   

  • nonenveloped
    • Adenoviridae

   

  • Caulimoviridae

   

  • Myoviridae

   

  • Phycodnaviridae

   

  • Tectiviridae

   

  • Papovaviridae

   

  • ss DNA
    • nonenveloped
      • Circoviridae

   

  • Parvoviridae

   

  • ds/ss DNA
    • enveloped
      • Hepadnaviridae

   

• RNA Viruses
  • ds RNA
    • positive strand
      • nonsegmented
        • enveloped
          • Cystoviridae

   

  • segmented
    • nonenveloped
      • Birnaviridae
      • Reoviridae

   

  • ss RNA
    • positive strand
      • nonsegmented
        • enveloped
          • Coronaviridae

   

  • Flaviviridae

   

  • Togaviridae

   

  • Arterivirus

   

  • nonenveloped
    • Astrovirus

   

  • Caliciviridae

   

  • Picornaviridae

   

  • Potyviridae

   

  • DNA step in replication
    • enveloped
      • Retroviridae

   

  • negative strand
    • segmented
      • enveloped
        • Orthomyxoviridae

   

  • nonsegmented
    • enveloped
      • Filoviridae

   

  • Paramyxoviridae

   

  • Rhabdoviridae

   

  • negative and ambisense
    • segmented
      • enveloped
        • Arenaviridae

   

  • Bunyaviridae