How HIV develops into AIDS?

Question 1

When was HIV first isolated?

Answer 1

1983

Question 2

What is HIV?

Answer 2

An RNA retroviruses with 2 main types.

Question 3

What is HIV-1?

Answer 3

Main cause of AIDS. Kills without treatment.

Question 4

What is HIV-2? How is if different to HIV-1?

Answer 4

Less virulent. Slower progression to AIDS.

Question 5

Where is HIV-2 an endemic?

Answer 5

West Africa

Question 6

What percentage of people with HIV-2 have a low/undetectable viral load?

Answer 6

30-40%

Question 7

How is a viral load calculated?

Answer 7

Number of HIV-2 genomes per millilitre of blood.

Question 8

How many human proteins does HIV recruit upon infection? What do these do?

Answer 8

273 human proteins. Mostly prevent immune system from terminating infection.

Question 9

What is meant by a lentivirus group?

Answer 9

Budding viruses with a complex genome that is tightly compressed. Many virion proteins that are generated through RNA splicing and cleavage vis viral protease. (HIV belongs to this group)

Question 10

By what amount does CD4 fall before opportunistic infections occur?

Answer 10

Below 200 cd4 cells/per cu mm.

Question 11

Examples of common infections post HIV?

Answer 11

Pneumocystis carinii, cytomegalovirus, herpes simplex virus

Question 12

Examples of fungi infections post HIV?

Answer 12

Candida, aspergillus, cryptococcus

Question 13

Example of common protozoan infections post HIV?

Answer 13

Toxoplasma

Question 14

How is HIV transmitted? Name 4.

Answer 14

Sexually, blood, blood products, maternally

Question 15

Which cell are infected with he HIV origionally?

Answer 15

CD4+ cells and macrophages.

Question 16

List the stages of HIV infections. Key words gp120, CD4, dendritic, mucosal, gp140.

Answer 16

. Envelope gp120 of HIV binds to CD4 molecules on helper T-cell surface, macrophages, dendritic cells and microglia.
. DC cells populate mucosa and project dendrites through the epithelial cells to gain exposure to mucosal surface.
. Binding of the CD4 molecule creates the fusion link between gp41 virus and host-cell chemokine receptors CCR5 and CXR4.
.

Question 17

How does HIV utilise the co-receptor CCR5?

Answer 17

They use this to infect memory T-cells, macrophages and Dendritic cells.

Question 18

How does HIV utilise co-receptor CXCR4?

Answer 18

Infect resting T-cells using this receptor.

Question 19

What does the gp120 envelope protein bind to?

Answer 19

CD4. This enables it to then bind to CCR5 or CXCR4.

Question 20

What does the gp120 and CCR5/CXR4 binding allow?

Answer 20

Release of gp41 which causes viral envelope to fuse with plasma membrane and release core of the virus into the cell cytoplasm.

Question 21

What happens when RNA genome enters the cytoplasm?

Answer 21

It is reverse transcribed into ds cDNA.

Question 22

What happens to ds cDNA?

Answer 22

DNA migrates to nucleus in association with viral integrase and integrates cells genome.

Question 23

What does cDNA integrate the cell genome as?

Answer 23

Provirus

Question 24

What induces some provirus transcription? What does this cause?

Answer 24

T-cell activation. Provirus transcribes into mRNA that directs synthesis of proteins Tat and Rev.

Question 25

What is the job of proteins Tat and Rev?

Answer 25

They change the pattern of provirus transcription and make it produce mRNA. These encode for protein constituents of the virion and RNA molecules that correspond to the HIV genome.

Question 26

Where do envelope proteins eventually travel to?

Answer 26

To the plasma membrane.

Question 27

Where do other viral proteins and viral genomic RNA eventually travel to?

Answer 27

Assemble into the nucleocapsids.

Question 28

What happens to new particles?

Answer 28

Bud from the cell and acquire lipid envelopes and envelope glycoproteins.