Lecture 7- Immune evasion Flashcards

1
Q

different roles of adaptive and innate immunity

A

innate more for fast pathogens and early response, adaptive can become important for limiting growth and initiating clearance

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2
Q

examples of innate responses to salmonella

A

complement, enterocytes producing defensins, changes in mucus production

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3
Q

example of a parasite and a specific immune response related to it

A

nematodes- Th2 mediates explusion, mast cells, IgE important
also see changes in mucus and gut motility

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4
Q

6 evasion strategies

A

speed
inhibition
avoid detection
change rapidly
spoke-screen effects
‘wrong response’

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5
Q

speed- example

A

colds and flu, replicate quickly and spread before adaptive immunity can kick in

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6
Q

inhibition- example

A

cytomegalovirus- uses a ‘decoy receptor’ to prevent chemokine action
HIV can reduce levels of MHC I on the surface of cells, inhibiting responses from Th/NK cells etc

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7
Q

avoiding detection- example

A

plasmodium- using RBCs, which lack MHC
papilloma virus- replication only at outer skin layers, which have less strong immune detection mechanisms

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8
Q

rapid change- example

A

influenza- antigenic variation, has 8 RNA segments making up its antigen and these can change (recomb., point mutations etc)
covid- variants, idea of ‘escape variants’
can also happen in parasites within a host- trypanosome surface glycoproteins

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9
Q

what are smoke-screen effects

A

causing a response to a non-protective antigen/part of the pathogen

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10
Q

smoke-screen effects- example

A

N. meningitidis, can create a large volume of T cells against non-protective antigens
non-specific activation of the immune system can be induced

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11
Q

‘wrong response’ examples

A

virokine production- secreted from host cells to create a better environment for host infection

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12
Q

example of an impact on the complement system

A

pseudomonas- inactivation of C3b and C5a, prevents recruitment of innate immune cells

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13
Q

how can bacteria prevent phagocytosis

A

‘slippery’ capsules, and shedding the surface antibodies quickly- e.g. S. pneumonia

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14
Q

example of how cross-species events can lead to pathology

A

adaptation to oriignal host, e.g. covid-2- bats have high IFN but low PRR response, so covid interferes w IFN but less PRR- leads to greater inflammation

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