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SP1 Virology > Lecture 5 2/6/24 > Flashcards

Lecture 5 2/6/24 Flashcards

1
Q

What factors impact whether or not an animal is resistant to infection?

A

-genetics
-endocrine
-age
-other factors

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2
Q

How does genetics play a role in resistance to infection?

A

related but different species can have slightly different genes that make them more (or less) resistant

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3
Q

How do corticosteroids impact viral immunity?

A

they are immunosuppressive

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4
Q

Why are pregnant animals often immunosuppressed?

A

due to the hormones that maintain pregnancy

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5
Q

How can nutrition play a role in viral immunity?

A

affects:
-mucous membrane and skin integrity
-phagocytes
-immune response

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6
Q

What affects can obesity have that impact immune response?

A

-pro-inflammatory
-immunosuppressive

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7
Q

How do polymicrobial infections impact viral immunity?

A

-deplete immune resources
-skew immune response
-alter pathology

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8
Q

Why are elderly animals more prone to infection?

A

-waning adaptive immunity
-innate immunity in higher gear, leading to more inflammatory responses

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9
Q

Why are young animals more prone to infection?

A

-immature immune systems
-B and T cells that function less optimally
-lack protective Ab titers
-some cell types are more susceptible at a younger age

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10
Q

How does colostrum protect a neonate?

A

-vaccinating mother leads to secretion of IgA into colostrum
-gut absorption of IgA leads to some level of protection

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11
Q

Why can maternal antibodies be a problem?

A

-interfere with vaccination and reduce vaccine efficacy
-prevent vaccination from mounting a memorable immune response

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12
Q

What is the window of susceptibility?

A

time at which maternal antibody level is no longer sufficient at protecting from infection, but is still high enough to prevent a protective vaccine response

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13
Q

What is the purpose of “boosting” a vaccine?

A

intent is to increase coverage of infant animals that may be in or out of the window of susceptibility, since we do not know exactly when the window is

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14
Q

Why is an antibody titer not always representative of a young animal’s actual immune status?

A

maternal antibodies can be picked up on a titer and cannot be differentiated from the animal’s own immune response

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15
Q

What are toll-like receptors?

A

pattern recognition receptors that recognize pathogen-associated molecular patterns

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16
Q

Which toll-like receptors are involved in viral immunity?

A

-TLR3
-TLR4
-TLR7
-TLR9

17
Q

Which RNA helicases in the cytoplasm of host cells are able to recognize viral RNA intermediates?

A

-RIG-1
-MDA5

18
Q

What are the characteristics of interferon?

A

-PRRs alter gene expression to produce type 1 interferon
-virus-infected cells produce type 1 interferon to protect neighboring cells
-type 1 interferon is released in paracrine manner to induce an antiviral state in nearby uninfected cells

19
Q

What are the characteristics of NK cells?

A

-first cells to respond to viral infection
-activated within hours
-produce large amounts of IFN-gamma, which leads to macrophage activation

20
Q

How do NK cells kill?

A

-NK cells express both activating and inhibitory receptors
-balance of receptors controls release of toxic granules
-lack of activation of an NK cell’s inhibitory receptors leads to NK cell degranulation

21
Q

What are the characteristics of macrophages?

A

-release cytokines that activate NK and CD8+ T cells following virus phagocytosis
-restrict viral spread by inactivating extracellular virions via free radicals and nitric oxide

22
Q

What are the general characteristics of adaptive immunity?

A

-requires antigenic priming
-can take days to activate
-results in memory generation

23
Q

What are the three components of the adaptive immune response?

A

-B cells
-CD8+ T cells
-CD4+ T cells

24
Q

What are the functions of antibodies produced by B cells/plasma cells?

A

-block viruses from interacting with host receptors/neutralization
-opsonize viruses to trigger phagocytosis via macrophages
-bind viral antigens on host cell surface to target them for ADCC by NK cells
-activate complement

25
Q

How can antibodies neutralize a virus?

A

-interfere with virion binding to cell receptors
-block uptake into cells
-prevent uncoating of genomes within endosomes
-lyse enveloped viruses via complement pathway

26
Q

What are the steps of antibody/complement opsinization?

A

-microbe is opsonized by antibody
-opsonized microbe bind to phagocytic receptors
-phagocyte receptor signals activate the phagocyte
-opsonized microbe is phagocytosed and killed

27
Q

What are the steps of ADCC?

A

-antibody binds to virus proteins expressed on cell surface
-NK cell receptors recognize BOUND antibody
-NK cells kill the antibody-coated cell

28
Q

How do enveloped viruses evade antibodies?

A

-bud from internal membrane, so no viral proteins on plasma membrane
-cell-to-cell spread through syncytia formation
-heavily glycosylated receptors
-rapid mutation of receptors

29
Q

How do persistent viruses evade antibodies?

A

latency within cells

30
Q

How do CD4+ T cells help CD8+ T cells?

A

-virus enters APC and exogenous antigens are presented to CD4+ T cell
-CD4+ T cell helps CD8+ T cell via cytokine production
-activated CD8+ T cell kills virus-infected cell

31
Q

How do CD4+ T cells help B cells?

A

-virus binds to IgM on B cell surface
-viral antigens are loaded onto MHCII molecules and presented to CD4+ T cell
-CD4+ T cell helps B cells via cytokine production
-B cells differentiate into plasma cells

32
Q

How do TH1 responses differ from TH2 responses in viral immunity?

A

-TH1 cytokines promote viral clearance through cell-mediated immunity
-TH2 cytokines promote viral persistence

33
Q

What are the characteristics of CD8+ T cells?

A

-effector function is to kill viral-infected cells
-T cell receptor recognizes viral peptide loaded on MHCI
-only kill infected cells, not extracellular virions
-generally effective against most viral diseases

34
Q

How can viruses evade T cells?

A

-encode proteins resistant to proteasome-mediated lysis and prevent MHC loading
-encode proteins that prevent transport of peptides into ER to prevent MHC loading
-down-regulation of MHCI

35
Q

What are the characteristics of memory in adaptive immunity?

A

-allows adaptive immunity to remember a pathogen after the initial contact
-key concept in vaccine strategy and design
-allows immune system to recognize pathogen faster and more efficiently

36
Q

What happens if the immune response is too weak/innappropriate?

A

-induction of TH2 response leads to less robust CD8+ T cell response
-wrong cytokine can be fatal
-CD8+ T cell response can take too long

37
Q

What happens if the immune response is too aggressive?

A

-too much inflammation
-potential for a cytokine storm

SP1 Virology (22 decks)

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