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Hugh's Intersystems > HIV > Flashcards

HIV Flashcards

1
Q

What is the function of HIV Rev protein?

A

It stabilised and transports unspliced and partially spliced RRE+ HIV RNA to the cytoplasm

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1
Q

What does Vif protein do?

A

Degrades APOBEC3

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1
Q

What does Pneuocystis jirovecii cause?

A

Pneumonia

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2
Q

What does TRIM5a do?

A

A endogenous human protein that destabilises the viral capsid

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2
Q

What viral protein is required for reactivation of transcription after a peroid of latency?

A

Tat

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2
Q

Apart from depleting T cells, what other effects does HIV infection have on the immune system in general?

A

Reduces neutrophil killing of bacteria

Increase B cell production of antibodies, including autoantibodies

Decrease macrophage phagocytosis, chemotaxis and killing

Decreases NK function

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3
Q

Which does HIV preferentially bind to early in infection, CCR5 or CXCR4?

A

CCR5

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3
Q

Why has vaccine development been so difficult?

A

Because envelope gp120 is highly variable

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4
Q

Which nucleoside is acyclovir an analogue of?

A

Guanosine

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5
Q

Is T cell depletion only caused by direct destruction of infected cells?

A

No, indirect destruction of uninfected cells also occurs.

eg Via incorporation of uninfected cells into syncitia

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5
Q

What adverse consequences of infection are seen despite viral control with HAART?

A

HIV-associated metabolic syndrome

Excess pathogens

Loss of Tregs

Microbial translocation through gut

CVS disease

Liver disease

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6
Q

How is it possible for HIV RNA production to occur in patients on HAART?

A

Latency in CD4+ T cells - particularly memory T cells

Replication in sanctuaries away from HAART therapy ie Brain, testis and gut

Replication in immunologically privileged sites

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7
Q

What type of virus is HIV?

A

Lentivirus

Icosahedral capside

Enveloped

+ssRNA

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8
Q

What is ribavirin?

A

A guanosine analogue that can target multiple viruses

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9
Q

What is the name of the viral protein that drives membrane fusion?

A

gp41

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11
Q

What does the HIV provirus’ promoter respond to?

A

Viral Tat protein

NFcappaB - a transcription factor involved in T cell activation

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12
Q

At mutation in delta32 CCR5 confers what for the human?

A

Homozygous confers resistant

Heterozygous confers slowed disease progression

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13
Q

Which has phosphate groups, nucleosides or nucleotides?

A

Nucleotides

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14
Q

What does the gag gene encode for?

A

Matrix

Capsid

Nucleocapsid

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15
Q

What long does primary HIV last?

A

1-4 weeks

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17
Q

What does APOBEC3G do?

A

It is an endogenous human protein that induces lethal hyper-mutations

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18
Q

What are some strategies HIV uses to block the expression of MHC-1?

A

Lysosomal degradation of MHC-1 by Nef and Vpu

Directing MHC-1 into the proteosome by Vpu

Tat inhibiting MHC-1 gene transcription

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19
Q

What causes chronic immune-activation? What is the consequence of it?

A

Lost of gut mucosal barrier > microbial products leak into systemic circulation > PAMPs stimulate immune cells > pro-inflammatory cytokines are elevated

  • CD4+ T-cells enter cell-cycle and die
  • CD8+ T cells become trapped in lymph nodes
  • B-cells make auto-Ab
20
Q

Why must you use 3 drugs in a combination therapy?

A

The chance of spontaneous viral mutation to evade 3 antivirals is highly improbable

21
Is decline in CD4 cells faster or slower with hepatitis G co-infection?
Slower
22
What is required for maturation of the viral particular after budding?
Activity of viral protease
23
What is the incubation period of primary HIV infection?
2-4 weeks
23
Why don't most antibodies to the HIV env neutralise the virus?
It is highly glycosylated
23
Why does acyclovir only target viral DNA replication?
Because it requires viral thymidine kinase to add the first phosphate group
25
What is the presentation of primary HIV infection?
Flu-like illness - Fever - Myalgia/arthralgia - Nausea/vomiting/diarrhoea - Weight loss
26
What is Kaposi's sarcoma caused by?
Infection by human herpesvirus 8
27
What does HAART stand for?
Highly active anti-retroviral therapy
27
How does Raltegravir work?
Inhibits integrase to block strand transfer
29
Where is the sequence variation highest in the HIV-1 genome?
In the *env* V region
30
How often to nucleotide changes occur to transcription of DNA from RNA?
Once per genome replication
31
How is viral fusion/entry inhibited by antivirals?
Coreceptor antagonists - For CCR5 = Maraviroc - For CXC4 = AMD-11070 Preventing unfolding - Enfuvirtide
32
How do the protease inhibitors of HIV maturation work?
They have analogous regions that maturation enzyme will bind to instead of the viral target
34
What does Vpu do?
Facilitates the release of fully infectious virions and counteracts innate immunity factors (degrades CD4, antagonizes tetherin, inhibits surface expression of CD1d)
36
Describes HIV's structure in terms of its layers
Outer bilipid membrane Matrix protein beneath, complexing with the envelope Capsid Nucleocapsid contain the RNA genome
37
What percentage of T-cells are lost within primary HIV-1 infection?
\>60% of mucosal T-cells
38
What do nucleoside analogues lack that prevents them from being added to the growing DNA chain by polymerase?
3' OH
40
Via what mechanism does HIV get from a local infection into the blood?
Virus infection dendritic cells \> these fuse with CD4+ T cells \> both travel to regional lymph nodes \> HIV is spread to activated CD4 T cells \> those infected cells enter the bloodstream
41
What is the of the coreceptors that HIV binds to after initially binding to CD4?
CCR5 CXCR4
42
Which can be detected first, HIV antigen or anti-HIV antibody?
HIV p24 Antigen
44
Which strain of HIV-1 is transmitted between people?
R5
45
What does tetherin do?
It is a endogenous human protein that inhibits virus release
46
Which protein is required for the maturation of HIV particles?
Gag-Pol precursor protein
47
What structural property do all nucleoside reverse transcriptase inhibitors share?
They lack the 3' OH
48
What is the limitation of targeting coreceptors with antagonists?
The other coreceptor is selected for
49
Why is the function of the long terminal repeat?
Acts as the HIV gene promoter once the provirus have been integrated into the host genome
50
What viral ligand binds CD4 of T cells and macrophages?
gp120
51
Which coreceptor is associated with greater pathogenicity?
CXCR4
53
Epidemiologically, how does the distribution of HIV infection differ in Australia compared to the rest of the world?
In Australia homosexual male are predominantly affected while in worldwide it is predominantly heterosexual women
54
Where does reverse transcription occur?
Within the viral capsid when it is in the cytoplasm of the infected cell
55
How is the long terminal repeat created?
Duplication of the end of the viral RNA sequence
56
In general, how do non-nucleoside reverse transcriptase inhibitors work?
Directly inhibit the reverse transcriptase enzymes by some mechanism

Hugh's Intersystems (15 decks)

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