Immunity Against Infection II Flashcards
How can viruses be EC when usually ic
Early stage of infection before they get into cells
Need complement, ab, phagocytosis, neutralisation,MHC II presentation
What is needed once they become ic
MHC I presentation on all cells
Activate th1 to activate CD8 and NK cells
What is the first response to viral infection
Type 1 ifn a and ifn b
What do ifn a and b induce which prevents viral replication
2’-5’ oligoadenylate synthetase : degrades rna
Kinase PKR : inhibits viral protein synthesis
Other than activating oligoadenylate synthetase and kinase pkr, what does ifn a and b do
Upregulate MHC I (stimulate CD8)
Upregulate dendritic and macrophage cells (apc)
Induce NK anti viral response
Induce chemokines to recruit lymphocytes
After induction of ifn a and b which stimulates apc and NK, what is released to promote th1 response (CD8 and NK stimulation)
Type II ifn y (from NK cells and apc like macrophages)
What is an issue with ifn a used to treat cancers
Can cause too much chemokine/cytokine production forming a storm
How do NK cells kill viral cells after stimulation by both ifn a/b and also by ifn y th1 response
Granules with perforin and granzymes
Which NK receptors activate them to kill viral cells by releasing granules
Activating receptors (recognise viral cell things like carbohydrates)
Which receptors inhibit killing of healthy cells by NK cells
Inhibitory receptors. They when bound non specifically to MHC I will make NK cells not kill it (killed by CD8 instead)
Which response comes last to clear viral infections
Cell mediated
What activates CD8
Ifn y which stimulates th1 response
Also MHC I presentation
Which2 ways do CD8 cells kill viral cells (apoptosis)
Secrete granzymes and perforin
Or binding of its FAS ligand to a Fas on host cell
What ensures local release of granules from CD8
Cell to cell contact via cams
Cytoskeleton rearrangements
What cytokine do CD8 release important in viral killing
Ifn y
Why are antibodies important in viral infections
In early stages before cell entrance.
Antibodies stop adherence eg iga
They cause complement lysis of enveloped viruses
Cause opsonisation via macrophages
Which antigens from influenza are used for the vaccine to produce antibodies
Hemagluttinin
Neuraminidase
What cells does hiv target
CD4, macrophages and dendrites (leads to opportunistic infections like candida,kaposi sarcoma)
Which cells control hiv to an extent
CD8 responses
Why is hiv hard to vaccinate
Antibodies don’t protect against it
What is dampened down by sars cob 2 which causes cytokine storm instead and viral replication
Ifn type 1
Which type of prr are inhibited by covid
Rig 1
What pro inflammatory tf is upregulated by covid
Nfkb
Why are antibodies important for parasite killing
Allow opsonisation
Adcc - coat large parasites for eosinophil killing via fc receptors
Also can cause lysis via complement
Which parasite is killed by igE stimulating eosinophils
Helminths - coated and killed
Why is the T cell/macrophage response also important for parasites
Some are intracellular and can survive in vesicles/macrophages
Hidden from antibody response
Give an example of a parasite ic so needs macrophages/th1 cell response
Leishmania (stay in macrophages)
