2.8 - DNA Replication Virus (Part 1)

• Viruses


  Acellular entities that assume some properties of life that allow them to be obligate intracellular parasites

  
• Viruses


  • Need hosts in order to thrive
  • Have a limited number of species as well as specific types of tissues for each viral species' host range
• Viral infection


  1. Attachment of the virion to the host cell

  2. Penetration when the virion enters the host cell

  3. Uncoating of the virion's capsid

  4. Replication of the viral genomic material, transcription and translation of viral proteins

  5. Assembly of viral particles to form progeny virions

  6. Release of progeny virions

  
• Lytic cycle


  A virus that causes the infection is described as virulent as upon the release of virion progeny, the host cell is lysed or broken apart to allow the progeny virions to go out of the host cell and infect other cells

  
• Lysogenic cycle


  The virus upon infecting a host does not immediately kill the infected cell but instead allows its genetic material to be incorporated into the host cell's genome. The viral infection is latent (hidden), until it is transduced and activated to eventually switch on to the lytic cycle.

  
• SARS-CoV-2 is described as a lytic virus as it is quite virulent upon infection of the respiratory tract
• SARS-CoV-2 is not a phage virus because it does not incorporate its genetic material in host cells (just like phage viruses do in bacterial cells)
• Asymptomatic individuals may still transmit the virus to other individuals
• Learning about the basic concepts of viral infection makes us better understand medical interventions done to combat COVID-19 such as the production of vaccines