HIV & AIDS

• What kind of virus is HIV?

  retrovirus
• Is HIV transmitted by a vector?


  No
• Can HIV survive outside of the human body?


  No
• How is HIV transmitted?

  By direct exchange of bodily fluids.
• Name ways that HIV is transmitted by exchange of bodily fluids.

  Sexual intercourse

  Blood donation

  Sharing needles

  Mother to child across a placenta

  Mixing of blood between mother and child during birth

  Breast milk
• Name the structural features of HIV.

  Two RNA strands

  Proteins e.g. reverse transcriptase

  Protein coat - capsid

  Viral envelope- lipid bilayer and glycoproteins

  Attachment proteins
• What is the lipid bilayer derived from?

  The cell membrane of the host helper T cell that the particle escaped from.
• What type of cells does HIV infect?

  lymphocyte helper T cells
• How does HIV avoid being recognised and destroyed by lymphocytes?

  By repeatedly changing it's protein coat.
• What is the first step of HIV reproduction?

  Attachment proteins (gp120 proteins) on the HIV bind to CD4 receptor proteins on T helper lymphocytes and macrophages.
• What is the second step of HIV reproduction?

  The virus’s lipid envelope fuses with the helper T-cell’s cell surface membrane.
• What is the third step of HIV reproduction?

  HIV RNA and HIV enzymes (reverse transcriptase and integrase) are enter the helper T cell.
• What is the fourth step of HIV reproduction?

  Reverse transcriptase takes the viral RNA and using host nucleotides coverts the RNA into a single strand of DNA.
• What is the fifth step of HIV reproduction?

  That single-stranded DNA is again reverse transcribed into a double-stranded DNA.
• What is the sixth step of HIV reproduction?

  Integrase grabs hold of the DNA and carries it through a nuclear pore into the nucleus of the cell.
• What is the seventh step of HIV reproduction?

  Within the nucleus of the cell the viral DNA finds the host chromosome. The integrase enzyme makes a nick in the hosts DNA and allows for HIV and allows for HIV to insert itself into the host chromosome.
• What is the eighth step of HIV reproduction?

  RNA polymerase transcribes the DNA in mRNA.
• What is the ninth step of HIV reproduction?

  The mRNAs encode for different viral proteins, capsid, enzymes, using the hosts ribosomes.
• What is the tenth step of HIV reproduction?


  A new HIV particle is assembled.
• What is the eleventh step of HIV reproduction?

  The particle buds of and protease enzyme breaks down the polyprotein chain so the HIV particle can fully mature.
• What is stage 1 (primary) of HIV infection?

  Short, flu-like illness - occurs one to six weeks after

  infection

  And/or no symptoms at all

  Infected person can infect other people
• What is stage 2 of HIV like?

  Lasts for an average of ten years

  This stage is free from symptoms

  There may be swollen glands

  The level of HIV in the blood drops to very low levels

  HIV antibodies are detectable in the blood
• What is stage 3 of HIV like?

  The symptoms are mild

  The immune system deteriorates because helper

  T-cells are killed

  Emergence of opportunistic infections and cancers
• What is stage 4 of HIV like?

  The immune system weakens because the helper T-cell count is so low.

  The illnesses become more severe leading to an AIDS diagnosis.
• what does hiv stand for?

  Human immunodeficiency virus
• What does AIDS stand for?

  acquired immune deficiency syndrome
• What are the signs and symptoms of HIV?

  pneumocystis carinii

  dramatic weight loss

  gum and mouth infections

  Kaposi's sarcoma
• When is someone said to have aids?

  when they can no longer produce antibodies
• What does aids stand for?

  Acquired immunodeficiency syndrome
• What does syndrome mean?

  a collection of symptoms which occur together and

  characterise a particular medical condition
• What does AIDS leave people vulnerable to ?

  Opportunistic infections – infections normally controlled in

  healthy people but potentially life-threatening in HIV infected

  people