Viral Structure

Viral Structure

Virion
1. Mature, released virus that can infect host cell
Genome
1. DNA
  1. Single or double stranded
  2. Linear or helical
2. RNA
  1. + sense
  2. - sense
  3. ambisense
Outer protection
1. capsid
  1. icosahedral
    1. polyhedron w/ 20 faces
  2. rigid structure
  3. resists drying, acid, detergent
2. Enveloped
  1. icosahedral capsid or helical ribonucleocapsid beneath envelope
  2. outer layer membrane
    1. lipids, proteins, glycoproteins
  3. disrupted by drying, acids, detergents, solvents
Viral Attachment
1. depends on capsid structure and glycoproteins in envelope
2. Tropism
  1. affinity for specific tissue type
3. attachment is very specific
  1. specific host cell receptors
4. Viral Attachment Proteins
5. naked capsid viruses
  1. small viruses: structural composition to adhere to specific host cell receptors
  2. large virus: structural composition and fiber-like proteins extending out of capsid to adhere
6. enveloped virus
  1. glycoproteins extend out from vision
    1. VAPs
      1. specificity
7. Viral Penetration
  1. naked capsid
    1. receptor-mediated endocytosis
    2. Viropexis
      1. Direct penetration of genome through host cell membrane via interaction between capsid and membrane
        picornaviruses
        papovaviruses
  2. enveloped viruses
    1. viral membrane fusion with host cell membrane
  3. Viral uncoating
    1. DNA
      1. carried to nucleus
        Not poxviruses
    2. RNA
      1. stays in cytoplasm
        Not orthomyxoviruses or retroviruses
    3. poxvirus
      1. encode own mRNA w/ vision-contained enzymes
    4. Retroviruses
      1. own polymerases for RNA synthesis
    5. RNA viruses
      1. encode own enzymes for transcription and replication
        host cell can't replicate viral RNA

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	Created by Corrie DeGraffenreid about 12 years ago