HIV and AIDS

Question 1

How is HIV transmitted?

Answer 1

• HIV is found in the blood and other bodily fluids
• HIV transmission occurs when the blood or body fluids gets transferred directly into the body
  This can happen through:
• unprotected sex
• direct blood to blood contact
• mother to child
• sharing needles

Question 2

Describe replication of HIV.

Answer 2

• attachment protein on HIV bonds. To protein receptor (CD4) on helper T cell
• the lipid envelope fuses with the cell surface membrane and the RNA and enzymes of HIV enter the cell
• the HIV reverse transcriptase converts the RNA into DNA and this is inserted into the cells DNA
• the HIV DNA is transcribed into mRNA to create new viral proteins and RNA to go into the new HIV
• the mRNA passes out the nuclear pore to a ribosome to create and assemble new viruses
• the HIV viruses break away from the helper T cell with a piece of its cell-surface membrane surrounding

Question 3

How does HIV cause the symptoms of AIDS?

Answer 3

• HIV specifically affects the helper T cells and kills them
• once the number of helper T cells reaches a critically low level then the person is suffering with AIDS
  They now can’t produce a sufficient immune response to pathogens:
• B cells cannot be activated therefore plasma cells can’t be formed and antibodies won’t be produced or released
• cytotoxic T cells aren’t stimulated so infected body cells can’t be killed
• phagocytosis also isn’t stimulated

Question 4

What happens if a person catches a disease with AIDS?

Answer 4

They cannot produce a sufficient immune response and can become seriously ill and ultimately die

Question 5

Why is HIV called a retrovirus?

Answer 5

Because it can write its DNA directly I to the host cells DNA allowing it to be replicated.

Question 6

Distinguish between HIV and AIDS

Answer 6

• HIV is the virus, AIDS is the disease.
• the HIV virus alone cannot cause death, only when the helper T cells drop to critically low levels can the virus become a disease and deathly
• HIV can become dormant and lay inside the cells DNA for years till a environmental trigger

Question 7

Why aren’t antibiotics affective against viral diseases like AIDS?

Answer 7

• Antibiotics kill bacteria by inhibiting their ability to synthesise the murein cell wall, therefore the cell is vulnerable to bursting through osmosis.
• Viruses don’t have cell walls and don’t have metabolic processes that can be inhibited, because they rely on host cell processes