Human immunodeficiency virus

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Human immunodeficiency virus

• HIV

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Human immunodeficiency virus

• HIV is the cause of acquired immune deficiency
  syndrome (AIDS)
• It is a single stranded RNA virus

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Human immunodeficiency virus

• It has a spherical shape with a diameter of about
  0.1mm
• It is outer lipid membrane is taken from material
  surrounding the host cell

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Human immunodeficiency virus

• The genetic material is enclosed in a protein
  caspid
• Within the caspid is also some molecules of
  reverse transcriptase

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Human immunodeficiency virus

• It is a member of a group of viruses called
  retroviruses.
• These viruses reverse the normal flow of genetic
  information

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Human immunodeficiency virus

• The reverse transcriptase makes copies of DNA
  from the viral RNA.
• The viral DNA made is known as a provirus

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Human immunodeficiency virus

• The provirus is then spliced into the host cells
  own DNA in an act of piracy.
• The host cell is now ready to make copies of the
  virus

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Human immunodeficiency virus

• Visit
• http//www.cellsalive.com/hiv1.htm
• http//www.hopkins-aids.edu/hiv_lifecycle/hivcycle
  _txt.html
• For a good overview of the life-cycle of HIV

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HIV and AIDS

• HIV is passed from human to human by
• Sexual contact with an infected person
• Shared use of a hypodermic needle with an
  infected person
• Injection of contaminated blood or blood products
• From an infected mother to her fetus or suckling
  baby

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HIV and AIDS

• HIV attacks the body helper T cells
• These are WBC lymphocytes
• The T cells have proteins on their surface which
  bind to the HIV

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HIV and AIDS

• The virus latches onto the T cells and uses them
  like door handles to gain entry to the cell
• Once inside the virus RNA is released into the
  cytoplasm

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HIV and AIDS

• The reverse transcriptase transcribes the viral
  RNA into DNA

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HIV and AIDS

• The enzyme integrase splices the viral DNA into
  the host cell DNA

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HIV and AIDS

• The infective virus now exists as a segment of
  DNA in the host cell.
• The cell may pass through a period of latency as
  the viral DNA awaits a chemical signal to prompt
  the host cell to start to produce new virus

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HIV and AIDS

• The host cell then transcribes the viral DNA and
  starts to make many copies of the viral RNA and
  viral protein

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HIV and AIDS

• These molecules spontaneously assemble into new
  viral particles

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HIV and AIDS

• The virus escapes the T cell to infect other T
  cells
• The infected T cell eventually is destroyed by
  the virus.

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Treatment of AIDS

• There is no cure or vaccine for AIDS or HIV
  infection
• A number of anti-HIV drugs are available
• The most well known of these zidovudine (AZT)
  works by blocking the viral reverse transcriptase.