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Flashcards in Immunology Deck (97)
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1

What are the 2 viral glycoprotein spikes that bind to the primary CD4 receptor?

Gp120 and gp41

2

What are the 2 7-transmembrane G-protein coupled receptors?

CCR5 and CXCR4

3

Which receptors are expressed primarily on T cells, and is called a T-trophic virus when using these receptors?

CD4 and CXCR4

4

Which receptors are expressed on macrophages, and are called m-trophic when using these receptors?

CD5 and CXCR5

5

For viral entry, what does the Gp120 do to CD4 and CCR5 ?

Pulls the virus closer to the cell membrane

6

Later, gp120 binds T0 CD4 and CXC4 receptors, and causes a conformational change to expose which marker?

Gp41

7

What is the role of Gp41 for viral entry?

Fuses viral and cell membranes --> allows viral RNA to penetrate the cell

8

What would happen if you are deficient in CCR5 or CXCR4?

You're immune to HIV

9

What is released into the cell when the HIV virus is uncoating?

+ ssRNA
RT
Integrase
Protease

10

What is the role of reverse transcirptase for HIV?

RNA --> DNA

11

What does the HIV use to integrate into the host cell DNA?

Integrase

12

Which host enzyme transcribes the viral DNA?

RNA polymerase II

13

Which cytokine is stimulated for its transcription during extrinsic stimuli, which therefor stimulates gene transcription of the HIV genome, causing the release of viral RNA into the cytoplasm?

IL-2 and its R

14

What happens to the viral RNA once it's inside the cytoplasm?

proteins are synthesized from it

15

What is the enzyme that cuts long protein chains into individuals proteins?

Protease

16

After sexual transmission, what "tissue" does HIV infect?

MALT

17

Which cells mediate the initial stages of HIV infection?

M-trophic cells

(CD4/CCR5)

18

A mutation in the what gene shifts the tropism of HIV to T-trophic, which allows HIV to infect CD4+ T cells?

Gp120

19

What reduces the # of Th cells in HIV infections?

Direct HIV-induced cytolysis
Cytotoxic Tc immune cytolysis
Chronic activation in response to the large HIV Ag challenge --> rapid terminal differentiation

20

Infected T cells are killed by what 4 mechanisms?

Accumulation of nonintegrated circular DNA copies of genoma
Increased permability of plasma membrane
Syncytia formation
Induction of apoptosis

21

What do activated CD4 Th cells release to initiate immune response, which activates macrophages, other T cells, B cells, and NK cells?

Cytokines

22

Under what CD4 levels do Ag-specific immune responses not work and humoral response is uncontrolled?

< 200 cells/uL

23

What 2 factors cause the outgrowth of opportunistic intracellular infections when CD4 levels get < 200?

Lose activating of macrophages
Delayed type (IV) hypersensitivity

24

What are neutralizing antibodies generated against to cause Ab-dependent cellular cytotoxicity response?

Gp120

25

What happens to CD8 levels in HIV infections? Why?

They ↓ b/c they require activation by CD4

26

A reduction in CD8 cells cause the possibility of what type of infections in HIV?

viral

27

Why does the infeciton of lymphocytes and macrophages is a way for HIV to escape immune control?

inactivation of key element of immune defense

28

What happens to gp120 for HIV to escape immune control?

Antigenic drift and heavy glycosulation

29

During what time is stage 1, stage 2, and stage 3 of HIV infections?

Stage 1: 0-24mo
Stage 2: 24-65mo
Stage 3: 65 onwards

30

During stage 1 of the HIV infection, which of the following markers peaks from 0-12 months and then drops to low levels?

Virus
CD4/T-cell count
Anti-HIV-1 Ab

Virus