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CMBM 3 > HIV > Flashcards

HIV Flashcards

1
Q

Describe retroviruses.

A

enveloped
single stranded (+)
two copies

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2
Q

How do retroviruses replicate?

A

through DNA intermediate using reverse transcriptase

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3
Q

Which two retrovirus cause disease?

A

Deltaretrovirus - complex (HTLV)

Lentivirus - complex (HIV-1, HIV-2)

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4
Q

What is RNA dependent DNA pol used for?

A

A DNA polymerase enzyme that catalyzes the process of reverse transcription.

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5
Q

What is integrase

A

viral protein that helps entry

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6
Q

What three major proteins do retroviruses have?

A

gag
pol
env

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7
Q

What are the 6 accessory genes for HIV1?

A 
tat
rev
nef
vif
vpr
vpu
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8
Q

Where does the retrovirus assemble and bud?

A

plasma membrane

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9
Q

Gag encodes for?

A

Structure:
matrix
capsid
nucleocapsid

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10
Q

Pol encodes for?

A

enzymes
reverse transcriptase (acts in cytoplasm)
integrase (integrates provirus DNA into host DNA)
protease (cleaves GAG protein; inhibits replication cycle)

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11
Q

Env encodes for?

A

Envelope proteins:
Surface Glycoproteins
Transmembrane Protein

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12
Q

What are the two regulatory proteins for HIV?

A

tat (transactivator - increase transcription)

rev (regulator of viral expression)

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13
Q

Is nef (negative regulation factor) a regulator?

A

NO, it down regulates CD4 and MHC class II

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14
Q

Why would nef downregulate CD4 and MHC II?

A

Virus wants to replicate before cell is attacked.

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15
Q

What is the function of vpu (Viral protein U)?

A

promotes degradation of CD4 and enhances release of virus from cell membrane

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16
Q

What is the function of vpr (Viral Protein R)? ***

A
  • transports DNA to nucleus

- increases virion production

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17
Q

What is the function of vif (viral infectivity)? ***

A

affects particle infectivity

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18
Q

Which two coreceptors are used for binding?

A

CCR5 (CD4 and macrophages)

CXCR4 (CD4 and T cell lines)

19
Q

Viral DNA is formed be what process?

A

reverse transcription

20
Q

What regulates transcription?

A

tat (transactivator)

21
Q

What allows export of virus from nucleus?

A

rev (regulator of viral expression)

22
Q

What helps virus release from cell membrane?

A

vpu (viral protein U)

23
Q

How are HTLVs transmitted?

A

blood, sexual, vertical

24
Q

HTLV-2 is more common in what population?

A

IV drug users

25
Q

Where is HTLV-1 prevalent?

A

Japan, Caribbean, tropics

26
Q

What are the clinical manifestations of HTLV-1?

A 
inflammation
spinal cord atrophy
hyper-reflexivity
leg weakness
urinary and fecal incontinence
27
Q

What is HTLV-2 associated with?

A

atypical T-cell hairy leukemia

28
Q

Where did HIV come from?

A

chimpanzee (SIV-simian immunodeficiency virus)

29
Q

List the four groups of HIV-1.

A

Group M - major
Group N - man from Cameroon
Group O - outlier “West Central Africa”
Group P - woman from Cameroon (gorilla simian immunodeficiency)

30
Q

How many clades (subtypes) of group M are identified?

A

9 (A, B, C, D, E, F, G, H, I, J, K)

31
Q

HIV-2 has how many groups?

A

8 (A, B, C, D, E, F, G, H)

32
Q

Which receptor does an M-tropic R5 virus use?

A

CCR5

33
Q

Which receptor does a T-tropic X4 virus use?

A

CXCR4

34
Q

Which protein is embedded in the membrane?

A

Gp41

35
Q

Which protein is the head of the stalk?

A

Gp120

36
Q

Describe the two types of conformational changes due to gp41 and gp120.

A

GP120 binds to Tcell and promotes binding of chemokine receptor.
GP41 undergoes a conformational change that exposes the fusion peptide which inserts into the Tcell membrane.

37
Q

Patients initiating treatment for Tb should also be screened for what infection?

A

HIV

38
Q

What is the 2-step laboratory test to diagnose?

A

Serum ELISA

confirmed by Western blot or Immunofluorescense

39
Q

What are some alternative tests for initial diagnosis?

A

rapid oral antibody test

results in 5 to 40 minutes

40
Q

What are some tests that may be performed post-diagnosis?

A

Quantition of virus in blood: HIV-1RT-PCR
Early marker of infection: Western blot for p24 antigen
correlate of HIV disease: CD4/CD8 Tcell ratio

41
Q

Be able to read western blot

A

Negative: total absence of bands associated with HIV1 (gp160/120, p24)

Positive: presence of at least 2 of the following bands:
p24
gp41
gp120/160

42
Q

How does a western blot work?

A

Control lane with proteins that are present in HIV-1
Patient’s serum lane is compared for bands

+Positive Must have at least 2 bands
p24
gp41
gp120/160

43
Q

What does p24 band indicate in HIV infection?

A

early infection

44
Q

What is acute HIV infection?

A

time between infection and seroconversion

  • must see detectable HIV RNA or DNA or p24
  • cannot be antibody based test

CMBM 3 (28 decks)

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