HIV

• HIV = the human immunodeficiency virus

  Leads to symptoms of AIDS
• Reverse transcriptase: converts viral RNA into DNA
• Integrase: allows the viral DNA to be inserted into the DNA of the host cell
• Protease: breaks up large polyproteins into smaller ones in order to assemble the virions
• HIV replication:

  1. The HIV virion enters the host cell, injecting the capsid into the cytoplasm into the T-helper cell
  2. Uncoating - the capsid partially dissolves, releasing the viral RNA
  3. The enzyme reverse transcriptase converts viral RNA to DNA
  4. Integrase causes the viral DNA to integrate into the genome of the host cell
  5. Protease breaks up large polyproteins into smaller pieces in order to assemble the virion. The new virions are released via exocytosis
• How HIV causes symptoms of AIDS:

  • affects T helper cell levels so cell-mediated immunity can’t occur
  • the person can’t fight off normal viruses and dies from these
• Why antibiotics aren’t effective against aids:

  • antibiotics kill bacterial infections, not viral infections
  • antibiotics destroy the murien cell wall of bacteria and cause water to enter the cell and it bursts and the bacterium dies
• The ELISA test - detects the presence of a protein:

  • antigens are immobilised on the surface
  • secondary detection antibodies are applied over the surface - these have enzymes on them
  • wash the plate with solution to remove any unattached antibodies
  • add the enzymes substrate. If antigens are present a detectable colour change will occur