Virus Structure

• Viruses are non-living structures which consist of nucleic acid (either DNA or RNA) enclosed in a protective protein coat called the capsid, sometimes covered with a lipid layer called the envelope.
• Function of attachment proteins: Attach to the cell surface of the host cell and allow the virus to enter the host cell
• Function of Lipid Envelope: Surrounds the virus and protects its genome
• Function of a capsid: protein coat that encapsulates the DNA/RNA
• Function of DNA and RNA in viruses: DNA and RNA are used to make viral proteins. (replication)
• What is the process of Viral Replication:

  1. Virus uses attachment proteins on it’s surface to bind to complimentary receptor proteins on the surface of a host cell.
  2. Virus injects its DNA or RNA into the host cell.
  3. Host Cell uses the DNA or RNA and Ribosomes to produce new Viral particles.
• After replication, How are virus particles released?

  1. Host cell bursts - all new particles are released at once
  2. “budding” - new particles leave one by one through the host cell membrane. (Often take a section of the membrane with them the “envelope” that surrounds some viruses)
• How do viruses cause disease?

  The Exiting of these Viruses, Damages host cells and causes disease.
• How does HIV cause disease?

  • For example, HIV infects cells of the immune system (such as helper T cells and macrophages)
  • When the newly replicated HIV particles exit, these host cells are destroyed
  • Over time, the immune system becomes severely compromised and this eventually leads to Acquired Immunodeficiency Syndrome (AIDS)