HIV Case Flashcards Preview

IHO Week 6 > HIV Case > Flashcards

Flashcards in HIV Case Deck (50):
1

How long can the latency period last in HIV?

up to 10 years

2

When do symptoms of HIV begin to appear?

when enough CD4 T cells have been destroyed

3

What are the ways hIV can be transmitted?

sexual transmission
exposure to infected blood products
use of contaminated clotting factors by hemophliacs
sharing contaminated needs
transplantation of infected organs
perinatal transmission

4

Describe the primary HIV Syndrome. WHen does it occur?

It's a flu-like illness occuring 6-12 weeks after infections

5

How many months does it take after hte primary HIV syndrome for the HIV antibody test to be positive? What's this called?

3-6 months
seroconversion

6

How can primary HIV syndrome be diagnosed n?them

viral load titer assay

7

What's the normal CD4 count? Below what level do people become at risk for opportunistic infections?

500-1200
below 500 they start to get opportunistic infections

8

What diseases are predictive of the progression to AIDS?

persistent shingels infecitons
oral candidiasis
oral hairy leukoplakia
kaposia sarcoma

9

A CD4 count below what maes a person considered to have advanced HIV or AIDS?

200

10

What infections are people at risk for under CD4 of 200?

pneumocystis carinii pneumonia
cryptococcal meningitis
toxoplasmosis

11

If CD4 is below 50, what are they at risk for?

mycobacterium avium
CMV
lymphoma
dementia

death

12

THe first antibodies that appear are to what viral proteins?

p24 and p55

(then p51, p120 and gp41)

13

What screening test do we use for HIV?

ELISA serology test

14

Why do we have to follow-up a positive ELISA?

it's sensitive but no specific

15

What's the confirmation test of choice?

western blot

16

HOw many bands are required for the diagnosis on western blot?

3 or more

17

RIsk of dying in three years after diagnosis is linked to what 5 indicators?

CD4 count below 200
viral load over 100,000
older than 50
injection drug user
having prior AIDs-defining illness

18

At this point in history, what percentage of HIV patients are alive 10 years post diagnosis?

84%
now considered a chronic disease

19

What are the CDC's HIV screening guildelines?

routine HIV testing to all peopl 13-64 years of age at least once regardless of risk, with repeat testing annually for persons with risk factros

20

What's the most common opportunistic infection in HIV?

pneumocystis jiroveci (carinii)

21

How do you diagnose a pneumocystic jirovecci infection?

symptoms
CXR
sputum silver stain

22

What are the classic symptoms of pneumocystis?

SOB, dry cough, fever

23

What sort of pneumonia is pnemocystis?

interstitial

24

What is HIV's genomic organization?

two copies of +ssRNA

25

What's the capsid symmetry?

icosahedral

26

Does it have an envelope?

yes

27

What are the two main glycoproteins that pierce through the envelop?

gp120 and gp41

28

What is the trophism for HIV?

CD4+ cells - usually T cells, but also CD4+ monocytes and macrophages

29

What are the three functional viral enzymes present wihtin the virus capsule that can become active as soon as the virus penertrates the host cells?

reverse transcriptase, protease and integrase

30

How does HIV gain entry into the host cell?

Two interactions occur: gp120 interacts with CD4 and then the gp41 interacts with either CXCR4 or CCR5

31

Mutation of which protein leads to immunity to HIV?

CCR5

32

CXCR4 can also bind what other molecule? What does this do in terms of HIV infection?

stromal derived factor 1 (SDF-1)

If inhibits HIV transmission

33

What does reverse trasncriptase do when the HIV gets inside the host cell?

It acts as an RNA-dependent DNA polymerase to creates a molecule of ssDNA from the ssRNA template
Then it acts as a DNA-dependent DNA polymerase to create the dsDNA

34

What happens to the newly synthesized dsDNA?

it gets integrated into the host genome by integrase

35

what do we call the virus once it's itnegrated into the genome?

provirus

36

What polymerase is used to replicate the viral genome once it's a provirus?

host RNA polymerase II

37

What are the two reasons HIV wants to replicate it's genome?

1. you need to reprogram the cell so that the cell will use it's transcription apparatus to suit HIV's needs
2. You need to get the viral enzymes and viral genome copies necessary to make more viral particles

38

Describe how HIV's genome is organized differently from ours

It differs mostly in its efficiency

It's small, so it uses all three reading frames to code for its genes

39

What are the three genes we need to know?

gag, pol and env

40

what does gag encode for?

capside proteins

41

what's the most important capsid protein and why?

p24, because we can use it for a diagnostic test

42

what does pol encode for?

the enzymes: reverse transcriptase, protease and integrase

43

what does env encode for?

the envelope proteins: gp120 and gp41

44

What are the two functions for the 3' and 5' LTRs on the HIV genome?

1. they act as integration sites for integrase
2. they are strong promoters for transcription factors in the host like NFkB, Sp1 and TBP

45

What are Tat and Rev and how do their functions differ? Which is active first?

they are virally encoded transcription factors

Tat is active first, then Rev

Tat promotes the early pattern of gene expression = spliced RNA so you get the enzymes needed for establishing the infection in the host cell

Rev is later and it promotes both spliced and unspliced RNA, which is used as the genomes for new viral particles

46

What happens to viral load after that first viremia spike? Why?

It drops down a bit and then only gradually increases for a while during clinical latency

because at that point you still have functional CD4 cells to work against it

47

What's the first antigen detectable in an HIV infection?

p24 antigen

48

What can we detect a few weeks after p24?

antibodies against p24

49

What antibody comes after p24?

anti-env antiodies

50

What's the goal of therapy for patients with HIV?

to reduce the level of circulating virus