HIV and Viruses

Question 1

What is HIV?

Answer 1

HIV (human immunodeficiency virus) is a virus that affects the immune system. It eventually leads to AIDS (acquired immune deficiency syndrome)

Question 2

What does HIV do?

Answer 2

Infects and kills helper T-cells, which act as host cells

Question 3

When do people with HIV develop AIDS?

Answer 3

When helper T-cell numbers in the body reach a critically low level

Question 4

What is the structure of HIV?

Answer 4

1. A core that contains RNA and some proteins (including reverse transcriptase needed for replication)
2. An outer coating of protein called a capsid
3. An outer layer called and envelope - made from membrane stolen from previous host cell
4. Sticking out from the envelope are copies of an attachment protein that help HIV attach to helper T-cells

Question 5

How does HIV replicate?

Answer 5

1. The attachment protein attaches to a receptor molecule on the cell membrane of the host helper T-cell
2. The capsid is released into the cell, it uncoats and releases RNA
3. Inside the cell, reverse transcriptase is used to make a complimentary strand of DNA from the viral RNA template
4. From this, double stranded DNA is made and inserted into the human DNA
5. Host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA
6. The viral proteins are assembled into new viruses, which bud from the cell and go on to infect other cells

Question 6

When infected with HIV, what is a latency period?

Answer 6

During initial infection period, HIV replicated rapidly and the infected person may experience severe flu-like symptoms. After this, HIV replication drops to a lower level. During the latency period the infected person won’t experience any symptoms

Question 7

Why don’t antibiotics work against viruses?

Answer 7

Abx kill bacteria by interfering with their metabolic reactions - they target bacterial enzymes and ribosomes - these are different to humans ones. Abx are only designed to target bacterial ones so they don’t damage human cells. Viruses don’t have their own enzymes and ribosomes - they use human ones so abs can’t inhibit them

Question 8

What are antiviral drugs designed to do?

Answer 8

Target the few virus-specific enzymes that exist

Question 9

Is there a cure for HIV?

Answer 9

No, but antiviral drugs can be used to slow down the progression of HIV infection and AIDS