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Infection > HIV/AIDS > Flashcards

HIV/AIDS Flashcards

1
Q

Where is HIV most endemic?

A

Africa

South Africa

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2
Q

Worldwide are there more males or females with HIV?

A

Females

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3
Q

UK are there more males or females? More hetero or men who have sex with men?

A

Men 67%

MSM 57%

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4
Q

Of heterosexual HIV transmission in UK what is the largest ethnic group affected?

A

Black african

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5
Q

What is a problem with heterosexual transmission/diagnosis?

A

They present later

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6
Q

What is the risk of contraction of Hep B hep C and HIV from needle stick?

A

B 1 in 3
C 1 in 30
HIV 1 in 300

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7
Q

What are patients with HIV at risk of?

A

Atypical infections
Yeast/fungi/protozoa
Reactivation of latent viral infections
Chronic infections

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8
Q

What is a retrovirus? What do you need to do before it can be read?

A

Single stranded positive sense RNA strand that uses reverse transcriptase to make DNA in infected host cell

Need to make a negative sense strand before reading

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9
Q

What % live with HIV don’t know they’re infected?

A

17%

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10
Q

What happens after the retrovirus has been converted to DNA?

A

Is then transcribed back to RNA in the usual way once incorporated in host DNA

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11
Q

What is HIV

A

Human immunodeficiency virus

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12
Q

Name some structures of a virus and what they do

A

ss or ds DNA or RNA
Capsid (protein shell protecting nucleic acid)
Envelope - present or not
Antigens - in envelope
Spikes - help adhere to cell surfaces
Envelope - or not (contains envelope proteins –> antigens) Derived from host cell membrane

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13
Q

What is the baltimore classification?

A

I –> VII

Based on type of DNA/RNA and method of replication

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14
Q

What happens to ss DNA when it incorporates into host?

A

Makes a 2nd copy straight away

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15
Q

What happens to ssRNA - sense vs ssRNA + sense when it gets into host?

A

ssRNA - sense can be read straight away

+ sense need to make a - sense strand before it can be read

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16
Q

What is better ss or ds in terms of mutations that inhibit viral growth?

A

ds is better as if ss subject to am mutation that will inhibit virus it has nothing to compare to to fix. whereas double strand can use the other strand to fix mutation

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17
Q

How is virus size suited to function?

A

It is small as they cannot exist outside host cell so they need to be small to get into host
Must be able to bind to host

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18
Q

How does a virus replicate in host?

A

Uses host machinary

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19
Q

Name some enveloped viruses

A 
Herpes 
HIV
Hep B Hep C
Ebola
Influenza
RSV (respiratory syncytial virus)
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20
Q

Name some non enveloped viruses

A

Paravirus
Adenovirus
Norovirus
HPV (Human Papilloma Virus)

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21
Q

Which is more likely to cause recurrent viruses enveloped or non enveloped?

A

Enveloped –> due to the antigen proteins in envelope that virus can change to become unrecognisable by immune system again

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22
Q

What is the best way to diagnose a virus?

A

Viral PCR

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23
Q

Which type of lymphocyte does HIV infect? Which other type of cell?

A

Ones with CD4 receptor (intracellular) T helper cells

Also monocytes/macrophages

24
Q

What is the response of T helper cells?

A

Signal cytotoxic T cells to kill

Active B cells to produce antibodies

25
Q

What are 3 important enzymes in HIV?

A

Reverse transcriptase
Integrase
Protease

26
Q

What is the nucleic acid of HIV?

A

ss RNA + sense strand

27
Q

What are the 10 stages of HIV replication?

A

1) Free virus
2) Attaches to cell with CD4 receptor and fuses
3) Empties viral contents into cell
4) ss RNA + sense converted to ds DNA by reverse transcriptase
5) viral DNA incorporated into host DNA by integrase
6) Transcription of cell DNA when cell divides makes viral proteins
7) Assembly of viral protein chains - come together
8) Proteins budded off in host cell membrane
9) Viral particles free from host cell
10) Maturation - protein chains in new viral particle cut by proteases into individual proteins that come together to make new working virus

28
Q

How do you catch HIV?

A

Bodily fluids - broken mucosal skin/blood/broken skin

29
Q

Name 4 ways HIV can be transmitted

A

Sex
Needles
Vertical transmission
Transfusion

30
Q

What are the 4 stages of HIV infection –> AIDs?

A

1) Seroconversion (Primary infection)
2) Latent infection
3) Symptomatic infection
4) Severe infection - AIDs

31
Q

Why is the viral load in blood relevant in transmission?

A

Increased viral load increased chance of transmission

32
Q

What happens during seroconversion?

A 
May feel general malaise/flu/splenomegaly/rash/lymphadenopathy
It is the point antibodies are made 
Viral load is at highest 
Most infectious
CD4 count dips then starts to increase
33
Q

What happens during latent infection?

A

CD4 count goes up
Big immune response
Viral load goes down <500
Viral load set point is set

34
Q

What does viral load set point determine?

A

Determines how severe virus gets - determines disease progression

35
Q

When do symptoms first appear?

A

<500cells/ul

36
Q

When are symptoms severe/lifethreatening

A

<200cells/ul

37
Q

What happens during symptomatic infection

A

CD4 goes down - symptoms get worse

Viral load goes up as immune system failing

38
Q

What happens during sever infection/AIDS

A

AIDS developed

<200cells/ul

39
Q

What is the CD4 count for stage I II III IV of HIV/AIDS?

A

> 500
<500
<350
<200

40
Q

What kind of infections might you see around 500 count of CD4

A

Herpes simplex
Varicella zoster
Bacterial skin infections
Fungal skin/oral

41
Q

What kind of infections might you see around 400 count of CD4

A

Kaposi’s sarcoma
Human Herpes Virus 8 (HHV8) that can cause cancer
Appears as red/purple spots under skin

42
Q

What kind of infections occur at lower CD4 counts 2-300

A

PCP (Pneumocystis Pneumonia)
CMV (Cytomegalovirus)
Lymphoma

43
Q

What kinds of things affect HIV transmission (4)?

A

Viral load
Method of transmission (e.g. type of sex vs needlestick vs transfusion)
Condom use
Breaks in skin or mucosa

44
Q

Which is the easiest way to transmit HIV? What next?

A

Transfusion 90-100%

Then anal intercourse

45
Q

Which factors help live a long life with HIV?

A

General health
Adherence to medication
Early diagnosis
Good treatment for complications

46
Q

How do you test for HIV (3)? What are the pros/cons for each

A

1st - screening - rapid <1 hour test finger prick can give good negative predictive value but problem with false positive

serology –> detect antibody and antigen - result on same day - issue with false negative

viral PCR –> detects HIV nucleic acid - very sensitive detects within a few days of transmission
Expensive and slow –> not for initial screening used for follow up and treatment response.

47
Q

Who should be tested?

A

Everyone if incidence is >2 in 1000

48
Q

What are 8 indications to be tested for HIV?

A

1) Derm - e.g. recurrent shingles
2) CNS - e.g. meningitis
3) Any blood abnormality
4) Onc - lymphoma/anal cancer
5) Gynae - Cervical intraepithelial neoplasia
7) Any STI
8) Resp - bacterial pneumonia/TB

49
Q

When should you start HIV treatment?

A

Straight away no matter of viral load as evidence says better outcomes

50
Q

What outcomes of HIV treatment do you want (6)?

A 
Undetectable viral load 
Increased CD4 count 
Reduce general inflammation
Reduce risk of transmission
Good quality of life
Normalise lifespan
51
Q

How do you treat HIV?

A

3 antiretroviral drugs (targets the 3 important enzymes)

52
Q

Why isn’t there a vaccine?

A

Because it is enveloped and the proteins mutate and are different in everyone so impossible to target

53
Q

Why give 3 ARVs?

A

Reduces chance of mutation
Suppresses replication more
One drug doesn’t suppress replication enough to avoid mutations

54
Q

How else can you reduce transmission of HIV?

A 
Increase condoms 
Prevent mother to child transmission
ARV treatment as prevention
Medical circumcision is protective in men
Post-exposure prophylaxis
55
Q

How could stem cells treat HIV?

A

From elite controllers who are the long term non-progressors - hasn’t worked yet

56
Q

What are the ethical implications of HIV?

A

Consider mother/child transmission
Consider legal requirement to tell people who they have been in contact with (anonymous)
Consider work risks e.g. nurse etc
Consider needlestick - having to take blood form infected patient to test for HIV
Psychological impact and stigma

Infection (14 decks)

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