4 host defense Flashcards
what is the parts of the innate immune system?
Innate Immunity
Recognition of patterns by PRRs Type I IFN secretion
Secretion of other soluble mediators: Cytokines – IL-1, TNFα,
IFNγ, chemokines, etc… Complement
NK cells
– direct killing of virus-infected cells by NK cells
– and, NK cells are a huge source of IFNγ pro
what is responsible fo the early antiviral host defense?
the innate immune response.
what cant you used INF gamma to treat a viral infection?
it is used in certain leukemias but it is limited by its side effects?
what kind of immune response does INF gamma cause?
it causes a Th1 immune response
too much causes flu like sympotoms
IFN-γ acEvates
macrophages.
acEvated macrophages, DC produce IL-12, TNF, IL1β
IL-12 does good things for NK cells, T cells
what cytokine is the actiovator for NK cells?
what secretes this?
IL-12 is the activator for cytokines.
it is from dendritic cells.
what aare the cytokines in the type 1 interferon response?
IFN -alpha
IFN - beta
what causes the release of the type 1 interferons?
the PRR recognize stuff that the cell does not have like dsRNA and it causes a IRF interferon response factor that binds to the ISRE
this makes IFN alpha and beta and causes them to be released.
they go out and bind to nearby cells causing them to go in to an antivirla state.
what is the reaction when the IFN alpha and beta bind to the receptor on others?
it makes the jak stat and this binds to DNA and causes them to make PKR and OAS
protein kinase R
oligoadenylate synthase.
what is PKr?
what is it activated by?
what does it do? by blocking what?
it is protein Kinase R
it binds to dsRNA and phosphorylates eIF-2alpha
eIF-2 alpha
delivers Met tRNA to the 40S ribosome to initiate polypeptide synthesis
PKR stops translation.
what is OAS?
what is it activated by?
what does it do once activated?
Type I IFNs activate PKR and 2’-5’ Oligoadenylate Synthase
OAS, like PKR, binds to and is activated by dsRNA
OAS makes oligo AAAA
oligo AAAA activates RNAse L – an endoribonuclease.
RNAse L degrades mRNA
OAS degrades mRNA
IFN-α and IFN-β induce ?
what happens to viral protein sythesis?
what happens to surface MHC I
what happens to NK cells?
causes the antiviral state.
decrease of viral protein sythesis
increase surface class 1 MHC
increase NKcells.
what are the proinflammatory cytokines?
what ones can induce fever?
major pro-inflammatory cytokine (TNF, IL-1, IL-6)
• Induces death signaling
pyrogen TNF, IL-1
what cytokine promotes the NK production of IFN gamma?
IL12
how do NK cells decide to kill a cell?
NK cells kill targets after assessing the balance between”
- inhibitory signals from class I molecules”
- activating signals from NK activating ligands”
In a “first response” to virus infection, cells upregulate Type I IFNs Cells also upregulate NK activating ligands in response to virus infection
p53 tells the cell to die or to survive?
what does it do?
it tells the cells to die
it makes bak pores that let out the cytochrome C
this activates caspase which goes into dna and breaks it up.
what does bcl-2 and bcl-XL do?
they stop the programmed cell death from happening.
Viruses encode proteins to prevent IFN binding!
viruses can stop the IFN signalling from within.
bind to PKR and inactivate it.
stop the activation of the PKR
stop eif2a from binding to PKR and activating it.
what PRR does influenza impair?
RIG-I
that senses the dsRNA fragments.
the viral IL-1β binding protein serves to sequester IL-1β and stop its ___________ activity
its pyrogenic activity
what are “control” proteins?
they are proteins that cells make to stop the complemnt proteins from binding to the cell surface and activating.
what do viruses do to get around the complemet proteins?
they make homologs of the control proteins that prevent the assembly of the MAC complex.
