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Immuno > HIV > Flashcards

HIV Flashcards

1
Q

HIV is a part of what family of viruses?

A

Lentivirus

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2
Q

There are two types of HIV, HIV-1 and HIV-2. Which one is common in the U.S.? Where is the other found?

A

Type one is common in the U.S., HIV-2 is west Africa

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3
Q

How long does it take for the HIV virus to cause an acute illness after initial infection?

A

2-6 weeks

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4
Q

What are the first symptoms of HIV?

A

non-specific, flu-like symptoms

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5
Q

How long does seroconversion take in an HIV infection?

A

6-9 weeks

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6
Q

True or false: there is a “window period” in HIV patients, where they are infected with HIV, but do not produce antibodies

A

True

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7
Q

What are the stages of HIV/AIDS?

A
  1. Acute stage (nonspecific symptoms)
  2. Latent phase
  3. ARC (severe symptoms)
  4. AIDS
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8
Q

What type of CAs are AIDS patients susceptible to?

A

Kaposi’s sarcoma

Non-hodgkin’s lymphoma

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9
Q

What causes cachexia of AIDS pts?

A

TNF-alpha

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10
Q

Which cells does HIV attack?

A

mainly CD4+ cells (Th cells)

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11
Q

What is the clinical definition of AIDS?

A

CD4+ count below 200 cells/mm^3

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12
Q

Once in the bloodstream, the virus attaches to what CD4 protein on T lymphocytes or mononuclear phagocytes? What happens after this?

A

gp120

This undergoes a conformational change to allow gp41 to insert into the plasmamembrane

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13
Q

What are the different coreceptors that various HIV strains will binds to?

A

CCR5 (called “R5” viruses)

CXCR4(called “R4” viruses).

(both are called “R5X4” virus strains)

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14
Q

HIV viruses that preferentially use CCR5 coreceptors usually infect which cells?

A

Macrophages

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15
Q

HIV viruses that preferentially use CXR4 coreceptors usually infect which cells?

A

T-cell

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16
Q

True or false: there is no switching the preference of HIV viruses between the CCR5 and CXR4 corecptor

A

False–will shift throughout infection

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17
Q

What are the two options for an HIV virus once it has entered a cell?

A

Replicate or insert into DNA

18
Q

What is a proviral state?

A

Where a virus exists only in the DNA of a host cell

19
Q

What signals HIV viruses in the proviral state to replicate?

A

NF(kappa)B is known to bind to HIV long terminal repeats (LTR’s) which control transcription of viral genes.

20
Q

What are the two cytokines that induce HIV transcription and viral replication in T lymphocytes?

A

Tumor necrosis factor-alpha and IL-2

21
Q

What are the 6 cytokines that induce HIV transcription in macrophages?

A

IL-1, IL-3, IL-6, TNF-α, IFN-gamma and GM-CSF

22
Q

What is the major role that macrophages play in helping the HIV virus?

A

Infected monocytes and macrophages are not as susceptible to lysis by the virus as T cells and may serve as an in vivo reservoir for the virus. This may serve to transport the virus throughout the body.

23
Q

Normal individuals have a peripheral blood CD4:CD8 of (BLANK), however AIDS patients may have a ratio as low as (BLANK).

A

2, 0.5

24
Q

What are the five ways in which the HIV virus kills Th cells?

A
  1. lysis of T cells
  2. interfere with protein production
  3. Syncytia formation of infected and uninfected T cells
  4. ADCC by antibody binding to gp120
  5. CTL destruction
25
Q

What are the two other mechanisms in AIDS that lead to immunodeficiency besides the death of T cells?

A
  1. Binding of free gp120 of uninfected T cells

2. Destruction of follicular network of lymphoid organs

26
Q

What is the protein HIV produces that down regulates class I MHC? What is the effect of this?

A

Nef protein which makes infected cells invisible to CTL’s

27
Q

True or false: Individuals who are infected with a strain of HIV that has a defective Nef gene do not progress to AIDS

A

True

28
Q

What accounts for the initial decline in the amount of HIV virus seen in pts: antibodies or CTLs?

A

CTLs

29
Q

What are the two major reasons that immune responses to the HIV virus are not effective?

A
  1. Insertion of DNA = undetectable

2. Virus has high mutation rate d/t reverse transcriptase

30
Q

What is the most frequent cause of death in pts with AIDS?

A

Fatal pneumonia from Pneumocystis carinii

31
Q

What are the three major obstacles/features of the HIV virus that makes vaccine development problematic?

A
  1. Genetic diversity/mutation
  2. Transmission occurs w/in cells
  3. Viral progression in the face of the immune response
32
Q

1% of caucasians carry a mutation in what gene that leads to resistance against developing HIV-1?

A

CCR5–(still susceptible to CXR4 strains)

33
Q

How long does it take for antibodies against HIV proteins to be detected serologically?

A

6-9 weeks

34
Q

What is the initial screening technique used to test for HIV?

A

ELISA

35
Q

What are the components of the ELISA for HIV?

A

Binding H9 antigens to a solid phase. pts serum antibodies bind. tagged antibodies to the pts antibody

36
Q

What are the two major sources of false positive tests of the ELISA for HIV?

A
  1. Multiparous females

2. Autoimmune pts

37
Q

What is used to r/o a false positive ELISA for HIV?

A

Second ELISA, then western blot.

38
Q

What is the PCR testing for HIV?

A

Detecting viral DNA by adding DNA polymerase + specific primer to DNA of pts

39
Q

What is RT-PCR?

A

Same as PCR, but detects RNA presence by using reverse trancriptase, then DNA pol.

40
Q

Which test would you use to determine whether a neonate has been infected with HIV from the parent? Why wouldn’t you use one of the other tests?

A

PCR or antigen detection ELISA. Cannot use others since mother’s antibodies will be present in baby.

Immuno (16 decks)

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