2: CELLS - HIV

Question 1

What is HIV?

Answer 1

• human immunodeficiency virus
• a virus that affects the immune system
• eventually leads to AIDS

Question 2

What is AIDS?

Answer 2

• acquired immune deficiency syndrome
• a condition where the immune system deteriorates and eventually fails, making the patient vulnerable to other illnesses

Question 3

What cells does HIV infect/act as host cells for HIV?

Answer 3

helper T-cells

Question 4

When do people with HIV develop AIDS?

Answer 4

when the Th-cell count drops below a certain level

Question 5

What happens to someone with HIV in the initial infection period?

Answer 5

• they experience flu-like symptoms
• HIV replicates rapidly

Question 6

What is the latency period?

Answer 6

• the period after the initial infection when HIV replication drops to a lower level
• the infected person won’t experience any symptoms
• can last for decades

Question 7

What are the initial symptoms of AIDS?

Answer 7

• minor infections of mucous membranes
• recurring respiratory problems

Question 8

What more serious infections can a patient become susceptible with as AIDS progresses?

Answer 8

• chronic diarrhoea
• severe bacterial infections
• tuberculosis
• toxoplasmosis of the brain
• candidiasis of the respiratory system

Question 9

What factors affect the progression of HIV to AIDS/survival time with AIDS?

Answer 9

• existing infections
• strain of HIV
• age
• access to healthcare

Question 10

What is the structure of HIV?

Answer 10

• spherical structure
• core containing genetic material (RNA) and some proteins
• outer layer called capsid
• extra outer layer called envelope made up of membrane stolen from the cell membrane of previous host cell
• attachment proteins on envelope which allow HIV to stick to host cell

Question 11

Describe the process of HIV replication

Answer 11

• the attachment protein attaches to a receptor molecule on the cell membrane of the host Th-cell
• capsid is released into the cell where it uncoats and releases the genetic material (RNA) into the cell’s cytoplasm
• inside the cell, reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template
• from this, double stranded DNA is made and inserted into the human DNA
• host cell enzymes are used to make viral proteins from viral DNA found within the human DNA
• viral components assembled into viruses which bud from the cell and go on to infect other cells. this ruptures and kills the host cell

Question 12

How can HIV be spread?

Answer 12

• unprotected sexual intercourse
• infected bodily fluids (eg: blood from sharing contaminated needles)
• passed from a mother to her foetus

Question 13

What is used to slow down progression of HIV/AIDS in an infected person?

Answer 13

• antiviral drugs
• antiviral drugs target virus-specific enzymes (eg: reverse transcriptase)