viruses

• viruses are non living.
• viruses are classified based on their nucleic acid type
• types of viruses

  • DNA
  • RNA
  • RNA Retrovirus
• examples of RNA Retrovirus

  • HIV
• examples of RNA viruses

  • tobacco mosaic
  • ebola
• examples of DNA viruses


  -lambda phage
• Lambda Phage


  • complex structure
  • DNA nucleic acid
  • host cells are bacteria and e-coli
• Tobacco mosaic virus


  • helix shape
  • have +ssRNA which can be directly translated to proteins
  • host cells are tobacco plants
• HIV virus


  • icosahedral shape
  • have single strand RNA
  • reverse transcriptase used to produced cDNA
  • host cells are white blood cells
• Ebola virus


  • envelope helix shape
  • have -ssRNA which needs to be transcribed to mRNA before being translated
  • host cells are humans
• lytic cycle


  • virulent virus DNA injected into host cell cytoplasm
  • viral protein made
  • genetic info/DNA replicated
  • virions assemble
  • cells LYSE
• lysogen pathway


  • non virulent virus injected into host cell cytoplasm
  • as a provirus
  • virus produces repressor proteins (stops transcription)
  • latent virus enters lytic cycle (when host cycle is weak)
• How do antivirals work?

  inhibit replication by...

  • forgetting viral enzyme so cant replicate DNA
  • forgetting viral antigen to prevent entry to host
• What is the focus of disease control?

  SPREAD OF INFECTION
• summary of ebola outbreak

  • poor hygiene caused virus to spread
  • 4900 deaths
  • no vaccine so focus was on reducing spread
• methods of control of virus

  • quarantine
  • sterilisation of equipment
  • rapid testing of people