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Immunology > Evasion of the Immune Response by Pathogens (23) > Flashcards

Evasion of the Immune Response by Pathogens (23) Flashcards

1
Q

Bacteria can interfere with _____ pathways. How?

A

TLR signaling pathways
redirecting the signaling pathways from pro-inflammatory to anti-inflammatory pathways

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2
Q

What is NF-kB?

A

protein complex that controls transcription of DNA, cytokine production, and cell survival

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3
Q

How does bacteria interfere with TLR signaling pathways?

A

make modified PAMPs
can bind to TLR-2 but are not recognized
so NO signal transduction occurs

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4
Q

What are MAPKs and their role in bacterial interference with TLR signaling pathways?

A

mitogen-activated protein kinase - type of protein kinase specific to the aa serine and threonine

involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock, and pro inflammatory cytokines

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5
Q

How does misdirection occur in bacterial interference with TLR signaling pathways?

A

when products from candida, Herminia, or mycobacteria trigger signaling through TLR2, leading to production of IL-10 (an anti-inflammatory cytokine)

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6
Q

Which bacteria neutralize defensins?

A

staphylokinase from s. aureus

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7
Q

Which bacteria destroys cathelicidins?

A

staphylococcal enzyme

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8
Q

Which bacteria binds and decreases defensin activity?

A

salmonella

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9
Q

Which bacteria blocks beta-defensing expression by airway epithelial cells?

A

klebsiella pneumoniae

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10
Q

What does s. aureus do?

A

inhibits phagocytosis by expressing Protein A
which binds to Fc portion of IgG
so, it prevents antibodies to bind to Fc receptor on phagocytic cells or activating the classical complement pathway

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11
Q

_____ bacteria such as pneumococci possess a thick hydrophilic capsule that phagocytes find difficult to bind to

A

Encapsulated

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12
Q

Streptococci produce ___ protein which can bind fibrinogen and masks C3b-binding sites. This protein also binds factor ____, inactivating bound C3b

A

M protein
H

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13
Q

What are the most important leukotoxins?

A

RTXs (repeats in toxin) proteins
leukotoxins kill leukocytes, especially granulocytes

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14
Q

What is the type III secretion system?

A

elaborate needle complex to convey effector molecules directly into the cytosol of effector cells

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15
Q

What is a successful pathogen?

A

cell survives - intracellular bacteria need to have a host cell

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16
Q

What are mechanisms of evading intracellular killing?

A
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17
Q

What are facultative intracellular bacteria and their mechanisms of survival?

A
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18
Q

How does listeria monocytogenes invade and spread?

A
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19
Q

What is antigenic variation?

A

one way bacteria can trick forces of the immunological response - periodically changes antigens i.e. undergoes antigenic variation

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20
Q

Antigens may ____ or _____ in the host during the course of an infection. Or, an organism can exist in nature as multiple antigenic type (serotypes or serovars)

A

vary
change

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21
Q

Some types of antigenic variation during the course of an infection result from ______

A

site-specific inversions
gene conversions
gene rearrangements in the DNA of microorganisms

22
Q

What is the significance of borrelia recurrentis and antigenic variation?

A

relapsing fever
bacteria multiply in tissues and cause a febrile illness until the onset of an immunological response a week or so later

23
Q

There are more than ____ serovars of leptospira spp.

A

250

24
Q

[DNA/RNA] viruses have a larger genome

A

DNA
RNA genomes are smaller so they don’t have room to accommodate genes dedicated to suppressing immunity

25
Q

Despite having a small genome size, some viruses encode ______

A

proteins that interfere at various levels
both specific and nonspecific host defenses

25
Q

What are virokines/immunoevasins?

A

some viruses make their own version of cytokines and chemokines
interfere with normal functioning of host cytokines

26
Q

Some viruses (human hepatitis C) block the effect of ____ by making soluble receptors of interferons or by blocking the activities of IL-12 and IL-18, both of which are required for IFN-gamma production

A

IFN-gamma

27
Q

Immunoevasions produced by viruses interfere with the processing of antigens that bind to ______ molecules

A

MHC I

28
Q

T/F: Viruses down regulate MHC I expression but can still by detected by NK cells

A

TRUE - THEY ESCAPE DETECTION BY T CELLS

29
Q

What is evasion through latency?

A

a state of irreversible nonproductive infection
consistent feature of herpesvirus
small number of viral genes during latency are expressed and are not detected by the immune system

30
Q

What is inhibition of apoptosis?

A

some viruses like poxviruses and herpesviruses produce caspase inhibitors that protect cells against death

31
Q

What are the main mechanisms of Treg immune suppression?

A

direct contact
suppressive molecules
interference with antigen presentation

32
Q

In direct contact regarding Treg, Treg binds to ______ which activates TGF-beta

A

T effector

33
Q

What is CTLA4 in direct contact for Treg immune suppression?

A

(another word for CD152) - its inhibitory receptors recruits TRAIL

34
Q

What does galectin 1 do?

A

binds to receptor on target cell & induces cell cycle arrest

35
Q

IL-10 is [immostimulatory/immunosuppressive]

A

immunosuppressive

36
Q

What does TGF-beta do primarily?

A

regulates T cell activation by reducing T cell proliferation
regulates macrophages
regulates B cell function

37
Q

Label 1-6

A
  1. IL-23
  2. IL-17
  3. IL-12
  4. IFN-gamma
  5. effector T cells
  6. activated NK cells
38
Q

IL-17 promotes primarily _____

A

Inflammation to get rid of extracellular bacteria and fungi

39
Q

What is immune deviation?

A

a phenomenon in which an adaptive response that has the potential to cause direct or indirect tissue damage is *converted to a less harmful response

caused by bias toward the differentiation of a specific type of effector T helper cell following the activation of a naive T cell

40
Q

T/F: Regarding immune privilege, even foreign antigens accessing these tissues do not generally trigger immune responses

A

TRUE

40
Q

What is immune privilege?

A

anatomical regions that are naturally less subject to immune responses

include CNS and brain, eyes, and testes

41
Q

T/F: Innate and adaptive leukocytes mount aggressive inflammatory responses against the intestinal microbiota

A

FALSE - do not
commensal bacteria are critical for maintaining overall gut immune homeostasis and oral tolerance to food antigens

42
Q

Gut microbes have particular effects on both _____ and ______

A

dendritic cells
regulatory T cells

43
Q

DCs that interact with certain species of commensal bacteria are rendered ______ and steer _______ rather than effector T cells

A

tolerogenic
steer differentiation of TH0 cells towards Treg

44
Q

Gut commensals have direct effect on _____ promoting their accumulation and influencing their cytokine production profiles. This results in ______

A

Tregs
anti-inflammatory microenvironment in the healthy gut

45
Q

T/F: B cells are much harder to tolerate than T cells

A

TRUE - generally regulated by peripheral mechanisms and by the absence of T cell help

46
Q

Antibodies tend to regulate antibody production through [positive/negative] feedback mechanisms

A

negative - can prevent the successful vaccination of newborn animals as a result of maternal immunity

47
Q

Treg cells secrete cytokines such as ____ and _____

A

IL-10
TGF-beta

48
Q

Th17 secretes the cytokine ______

A

IL-17

Immunology (36 decks)

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