AQA A Level Biology

Revision Notes

2.6.4 AIDS


Symptoms of AIDS

  • Immediately after infection with HIV people often suffer mild flu-like symptoms
  • These symptoms pass and for a period of time infected people might not know they are infected
  • After several months or years, the viral DNA replicated by the HIV virus particles becomes active
  • They gradually destroy and reduce the number of helper T cells present in a host
  • This is detrimental as helper T cells play an important role in the specific immune response
    • They stimulate B cells, the production of antibodies and increased rates of phagocytosis
  • When an individual can no longer produce antibodies they are said to have advanced acquired immunodeficiency syndrome (AIDS)
  • As they can no longer produce antibodies against pathogens they are immuno-comprised and unable to fight off infections
  • They begin to suffer from diseases that would usually cause very minor issues in healthy individuals
    • These diseases are described as opportunistic
    • Tuberculosis (TB) is a common example
  • It is these opportunistic diseases that cause an individual with advanced AIDS to die

Treatment of AIDS

  • As of yet, there is no cure for AIDS
  • There are many drugs that are very effective at slowing the spread of the virus within the body
  • When provided with adequate medical care individuals with HIV have the same life expectancy as those without the virus

Antibiotics and viruses

  • Antibiotics are commonly used to kill bacteria or limit bacterial growth
  • The mechanism by which they work can vary. Some interfere with the metabolism of bacterial cells while others prevent protein synthesis
  • Antibiotics are ineffective against viruses as they are non-living
  • Viruses are particles and not cells
    • They have no metabolism or cell structure for antibiotics to act on and disrupt

Exam Tip

Try not to confuse the terms HIV and AIDS. Many people often use them interchangeably when they actually mean different things.

  • HIV is a virus
  • AIDS is the disease caused by HIV


Alistair graduated from Oxford University in 2014 with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems and Societies.

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