HIV and viruses

Question 1

What does HIV stand for?

Answer 1

Human immunodeficiency virus

Question 2

What does HIV lead to?

Answer 2

Acquired immune deficiency system (AIDS)

Question 3

What does HIV do to helper T-cells?

Answer 3

Infects and kills them

Question 4

What do the helper T-cells act as for the virus?

Answer 4

Host cells

Question 5

What is the effect of not having enough helper T-cells?

Answer 5

They send chemical signals that activate phagocytes, cytotoxic t-cells and b-cells so without enough the body is not able to develop an effective response to infections

Question 6

When does someone with HIV develop AIDS?

Answer 6

When the number of helper T-cells in the body reach a critically low level

Question 7

What is the latency period?

Answer 7

When HIV replicate slows after replication is rapid after initial infection.

Question 8

What happens during the latency period?

Answer 8

It can last for years and the infected person won’t experience any symptoms so they won’t know the have it

Question 9

What is the average time between infection with HIV and development of AIDS without treatment?

Answer 9

10 years

Question 10

What are initial symptoms of AIDS?

Answer 10

Minor infections of mucous membranes and recurring respiratory infections

Question 11

What are some symptoms as AIDS progresses?

Answer 11

They become more susceptible to more serious infections including chronic diarrhoea, severe bacterial infections and tuberculosis

Question 12

What happens during the late stages of AIDS?

Answer 12

Patients have a very low number of immune system cells and can develop a range of serious infections such as toxoplasmosis of the brain and candidiasis of the respiratory system

Question 13

What are the components of a virus particle?

Answer 13

Core
Envelope
Capsid
Attachment proteins

Question 14

What does the core contain?

Answer 14

Genetic material in the form of RNA

Enzyme reverse transcriptase

Question 15

What are attachment proteins used for?

Answer 15

Helping the HIV attach to the host helper T-cell

Question 16

When can HIV only reproduce?

Answer 16

When inside the cells of the organism it has infected

Question 17

What is the first stage in HIV replication?

Answer 17

The attachment protein attaches to a receptor molecule on the cell membrane of the host helper T-cell

Question 18

What is the second stage in HIV replication?

Answer 18

The capsid is released into the cell where it uncoats and releases genetic material (RNA) into the cell’s cytoplasm

Question 19

What is the third stage in HIV replication?

Answer 19

In the cell, reverse transcriptase is used to make a complimentary strand of DNA from the viral RNA template

Question 20

What is the fourth stage in HIV replication?

Answer 20

Double stranded DNA is made and inserted into the human DNA

Question 21

What is the fifth stage in HIV replication?

Answer 21

Host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA

Question 22

What is the last stage in HIV replication?

Answer 22

The viral proteins are assembled into new viruses, which bud from the cell and go on to infect other cells

Question 23

Why dont antibiotics work on viruses?

Answer 23

Antibiotics target the bacterial enzymes and ribosomes but viruses dont have their own enzymes and ribosomes, only the ones from the host cell

Question 24

What are anti-viral drugs?

Answer 24

They are designed to target the few virus-specific enzymes that exist

Question 25

What is the best way to control HIV?

Answer 25

Reducing its spread

Question 26

How is HIV spread?

Answer 26

Through unprotected sex, through infected bodily fluids, to a baby from a HIV-positive mother whilst pregnant