HIV Essay

Question 1

Describe the overall structure of the human immunodeficiency virion

Answer 1

A retrovirus that is roughly spherical and is around 120nM

Question 2

What is the group-specific antigen (gag)

Answer 2

A structural protein expressed as gag/gag-pol poly protein. It is cleaved into capsule protein and matrix proteins

Question 3

What is the envelope protein (Env)

Answer 3

It is a gp 160 glycoprotein which is cleaved to gp 120 and 41. The gp makes the head and 41 is transmembrane proteins of the surface glycoprotein. GP 120 is involved in attachment with CD4 antigen and gp41 mediates fusion to host cells after binding to CCR5 (macrophages or CXCR4CT - cells).

Question 4

What is the role of reverse transcriptase

Answer 4

Converts single-stranded viral RNA genome into double-stranded DNA that is integrated into the host genome by the viral enzyme integrase

Question 5

What is the role of protease

Answer 5

Cleaves newly synthesised poly proteins. Without effective proteases HIV remains uninfectious

Question 6

What is the role of integrase

Answer 6

Enables HIV genetic material to be integrated into the DNA of the infected host cell in the form of “provirus”

Question 7

Describe how attachment occurs in the HIV life cycle

Answer 7

Binding of gp24 on the surface of the virion to CD4 on the surface of immune cells as well as gp41 to CR5/CXCR4. The virion cone penetrates the cell.

Question 8

Describe reverse transcription as a part of the HIV life cycle

Answer 8

Genomic viral RNA is copied into DNA. Viral DNA and virion protein translocates into the nucleus

Question 9

Describe integration as a stage of the HIV life cycle

Answer 9

Viral DNA integrates intothe host cell DNA to provirus

Question 10

Describe transcription as a stage of the HIV life cycle

Answer 10

Viral RNA is synthesised by cellular RNA polymerase II

Question 11

Describe translation as a stage of the HIV life cycle

Answer 11

mRNA is translation onto proteins and are processed by protease

Question 12

Describe budding as a stage of the HIV lifecycle

Answer 12

Venous are assembled at one cell membrane and bud-off.

Question 13

What % of infections are acute or symptomatic

Answer 13

50-90 percent

Question 14

What is seroconversion

Answer 14

When there is a detectable level of antibodies to HIV in the blood (present within months of infection)

Question 15

What symptoms occur 5-30 days after exposure

Answer 15

Mild flu-like symptoms such as fever, fatigue, malaise, headache, nausea, vomiting and diarrhoea

Question 16

What is malaise

Answer 16

A general feeling of discomfort on illness

Question 17

On average how many virions are produced and destroyed during acute/ primary infection.

Answer 17

10 ^10

Question 18

How long can the asymptomatic/persistant phase last

Answer 18

≥ 10 years

Question 19

What symptoms are present during the resistant phase

Answer 19

Mild symptoms (eg swollen glands) or no symptoms

Question 20

The levels of which cells drop doing the persistent phase

Answer 20

CD4 T cells

Question 21

What is another name for the symptomatic phase

Answer 21

AIDS

Question 22

What happens to immune cell levels during the symptomatic phase

Answer 22

CD4 and CD8 T cell levels deteriorate

Question 23

Example of opportunistic cancer and opportunistic infection

Answer 23

Kaposi sarcoma and tuberculosis

Question 24

What happens to viral replication during the symptomatic phase

Answer 24

Virus replication os reamplified

Question 25

What effects can HIV infection have on the intestinal mucosa

Answer 25

Diarrhoea, increased GI inflammation, increased intestinal permeability and malabsorption of bole and vitamin B12

Question 26

What does anti-retrovoral therapy (art) do?

Answer 26

Reduce viral load which disease

Question 27

How does reducing the viral load halt design

Answer 27

Prevents and reduces resistant variants
Leads to active immune reconstitution (increase in CD4 cells)
Prolongs and improves the quality of life

Question 28

What do nucleotide and nucleoside reverse transcriptase inhibitors (NRTIs) do and give examples

Answer 28

Block replication by incorporating onto the elongating strand of dna causing chain termination (cabacavir, didanusine and lamivudine).

Question 29

What does non-nucleoside reverse transcriptase inhibitors do (and give examples)

Answer 29

Inhibit hiv by bonding non-competitively to the revenge transcriptase (efavarinz and revtrapine)