Flashcards in Immunology Deck (97)
What are the 2 viral glycoprotein spikes that bind to the primary CD4 receptor?
Gp120 and gp41
What are the 2 7-transmembrane G-protein coupled receptors?
CCR5 and CXCR4
Which receptors are expressed primarily on T cells, and is called a T-trophic virus when using these receptors?
CD4 and CXCR4
Which receptors are expressed on macrophages, and are called m-trophic when using these receptors?
CD5 and CXCR5
For viral entry, what does the Gp120 do to CD4 and CCR5 ?
Pulls the virus closer to the cell membrane
Later, gp120 binds T0 CD4 and CXC4 receptors, and causes a conformational change to expose which marker?
What is the role of Gp41 for viral entry?
Fuses viral and cell membranes --> allows viral RNA to penetrate the cell
What would happen if you are deficient in CCR5 or CXCR4?
You're immune to HIV
What is released into the cell when the HIV virus is uncoating?
What is the role of reverse transcirptase for HIV?
RNA --> DNA
What does the HIV use to integrate into the host cell DNA?
Which host enzyme transcribes the viral DNA?
RNA polymerase II
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
What happens to the viral RNA once it's inside the cytoplasm?
proteins are synthesized from it
What is the enzyme that cuts long protein chains into individuals proteins?
After sexual transmission, what "tissue" does HIV infect?
Which cells mediate the initial stages of HIV infection?
A mutation in the what gene shifts the tropism of HIV to T-trophic, which allows HIV to infect CD4+ T cells?
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
Infected T cells are killed by what 4 mechanisms?
Accumulation of nonintegrated circular DNA copies of genoma
Increased permability of plasma membrane
Induction of apoptosis
What do activated CD4 Th cells release to initiate immune response, which activates macrophages, other T cells, B cells, and NK cells?
Under what CD4 levels do Ag-specific immune responses not work and humoral response is uncontrolled?
< 200 cells/uL
What 2 factors cause the outgrowth of opportunistic intracellular infections when CD4 levels get < 200?
Lose activating of macrophages
Delayed type (IV) hypersensitivity
What are neutralizing antibodies generated against to cause Ab-dependent cellular cytotoxicity response?
What happens to CD8 levels in HIV infections? Why?
They ↓ b/c they require activation by CD4
A reduction in CD8 cells cause the possibility of what type of infections in HIV?
Why does the infeciton of lymphocytes and macrophages is a way for HIV to escape immune control?
inactivation of key element of immune defense
What happens to gp120 for HIV to escape immune control?
Antigenic drift and heavy glycosulation
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