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Flashcards in the immune system (HIV) Deck (17)
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1
Q

what does HIV stand for?

A

human immunodeficiency virus

2
Q

what is HIV?

A

virus that affects the immune system

3
Q

what does HIV eventually lead to?

A

AIDS

4
Q

what does AIDS stand for?

A

acquired immune deficiency syndrome

5
Q

what is AIDS?

A

condition where the immune system deteriorates and eventually fails
makes someone more vulnerable to other infection

6
Q

when do people with HIV develop AIDS?

A

when T helper cell numbers reach a critically low level

7
Q

what does HIV do?

A

infects T helper cells, which act as host cells for the virus
immune system cannot offer an effective response

8
Q

what is the structure of HIV?

A

core= contains genetic material (RNA) and some proteins
capsid= protein coat
envelope= lipid membrane stolen from the cell membrane of a previous host cell
attachment proteins= help HIV attach to the host T helper cell

9
Q

what enzymes are present in HIV?

A

reverse transcriptase, integrase, protease

10
Q

what is the role of reverse transcriptase?

A

catalyses the use of viral RNA to form viral DNA by reverse transcription

11
Q

what is the role of integrase?

A

catalyses the integration of the viral DNA into the genome of the host cell

12
Q

what is the role of protease?

A

catalyses the break up of large polypeptides into smaller pieces- essential in assembling new viral particles

13
Q

how do antiviral drugs work?

A

target specific enzymes, such as reverse transcriptase

14
Q

when do people with HIV develop symptoms?

A

during the initial period HIV rapidly replicates
the infected person develops flu like symptoms
after replication decreases this is known as the latency period
during this time people don’t get symptoms

15
Q

why don’t antibiotics work against viruses?

A

antibiotics kill bacteria by interfering with their metabolic reactions
viruses do not have their own enzymes/ribosomes, so use host cells
antibiotics cannot inhibit because they only target bacterial cells not human cells

16
Q

how can HIV spread?

A

unprotected sexual intercourse
infected body fluids
passed onto a positive mother to the foetus

17
Q

how does HIV infect host cells?

A

1) HIV binds to the CD4 receptor on T helper cells
2) viral and cellular membranes fuse
3) HIV virion penetrates the CD4 receptor membrane and enters the host cell
4) capsid is injected into the cytoplasm of the T Helper cell
5) capsid dissolves in a process called uncoating, which releases viral RNA
6) reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template
7) double stranded DNA is made and inserted into human DNA (categorised by intergrase)
8) viral RNA is transported out of the nucleus into HIV subunits and genetic material for new viruses
9) protease breaks polyproteins to make virions
10) in budding, virions are released out of the cell into circulation to infect other cells