HIV Infection


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•  Effects of HIV on the immune system and methods of transmission

The Human Immunodeficiency Virus (HIV) is a retrovirus that infects helper T cells, disabling the body’s adaptive immune system

  • It causes a variety of symptoms and infections collectively classed as Acquired Immuno-Deficiency Syndrome (AIDS)

Effects of HIV

  • HIV specifically targets the helper T lymphocytes which regulate the adaptive immune system
  • Following infection, the virus undergoes a period of inactivity (clinical latency) during which infected helper T cells reproduce
  • Eventually, the virus becomes active again and begins to spread, destroying the T lymphocytes in the process (lysogenic cycle)
  • With a reduction in the number of helper T cells, antibodies are unable to be produced, resulting in a lowered immunity
  • The body becomes susceptible to opportunistic infections, eventually resulting in death if the condition is not managed

Progression of AIDS

AIDS progression

Transmission of HIV

  • HIV is transmitted through the exchange of body fluids (including unprotected sex, blood transfusions, breastfeeding, etc.)
  • The risk of exposure to HIV through sexual contact can be minimised by using latex protection (i.e. condoms)
  • A small minority of people are immune to HIV infection (they lack the CD4+ receptor on TH cells that HIV requires for docking)
  • HIV is a global issue, but is particularly prevalent in poorer nations with poor education and health systems

Mechanisms of HIV Infection

HIV transmission