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History of genetics
Learn introductory genetics with Braimy- B.Sc agriculture
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a) Attachment:

  • The attachment refers to the first encounter of virus particles with host cells, which involves two kinds of host proteins on the plasma membrane: (1) attachment factors and (2) viral receptors.
  • The attachment factor on the cell surface recruits and holds the virus particles, thereby facilitating the interaction of the viral particle with the entry receptor.

b) Penetration:

  • Following attachment of the virus particle on the target cells, the next step is the penetration into the cytoplasm.
  • The mechanism for the penetration differs, whether enveloped or not. For enveloped viruses, one of the following two mechanisms is used: direct fusion and receptor-mediated endocytosis.
  • For nonenveloped naked viruses, receptor-mediated endocytosis is used for penetration.

c) Intracellular Trafficking:

  • Following successful penetration inside cells, the virus particles need to get to an appropriate site in the cell for genome replication. This process is termed intracellular trafficking.
  • For viruses that replicate in the cytoplasm, the viral nucleocapsids need to be routed to the site for replication.
  • In addition, for viruses that replicate in the nucleus, the viral nucleocapsids need to enter the nucleus. For many DNA viruses, the viral nucleocapsids are routed to the perinuclear area via microtubule-mediated transport.

d) Uncoating:

  • As the virus particles approach to the site of replication, from the cell periphery to the perinuclear space, the viral genome becomes exposed to cellular machinery for viral gene expression, a process termed uncoating.
  • For viruses that replicate in the nucleus, the viral genome needs to enter the nucleus via a nuclear pore.
  • For viruses with a larger genome, the docking of nucleocapsids to a nuclear pore complex causes a partial disruption of the capsid (eg, adenovirus) or induces a minimal change in the viral capsid (eg, herpes virus), allowing the transit of DNA genome into the nucleus.

e) Assembly: Viral particles are assembled from proteins and NA.

f) Maturation: Completed particles are referred to as virions.

g) Release: by exocytosis (budding) or by lysis of the host cell.

Virus: Reproduction | Texas Gateway

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