12 - Immunity to Parasites And Fungus (Steph)

Question 1

protozoan parastes

Answer 1

• unicellular, mostly intracellular
• many motile, many free living and found in contaminated water
• others move from arthropod vectors

Question 2

metazoans

Answer 2

helminth worms, mostly extracellular

Question 3

what immune response does a protozoan parasite elicit when in bloodstream, gut or interstitial fluids

Answer 3

humoral antibody responce

Question 4

when a protozoan parasite is in its intracellular life cycle, what immune response does it elicit

Answer 4

cell-mediated immune response

Question 5

what is malaria caused by

Answer 5

Plasmodium spp. carried by female anopheles mosquitos

Question 6

plasmodium has what kind of life stages

Answer 6

multiple extracellular and intracellular stages of infection

Question 7

throught the lifecycle of plasmodium, where does it move within the body

Answer 7

moves through liver/RBCs

Question 8

what are the intracellular phases of plasmodium able to resist

Answer 8

Ab-based responses

Question 9

how does plasmodium avoid good immune stimulation

Answer 9

• short blood circulation time free parasite stage prevents good immune stimulation
• Ab responses avoided by outer coat of shedding

Question 10

T/F: Babesia bovis is multicellular

Answer 10

false

Question 11

what clinical signs does Babesia bovis cause

Answer 11

hemolytic anemia (cattle fever, piroplasmosis)

Question 12

how is Babesia bovis transmitted?

Answer 12

by bites from infected larval ticks (ixodes)

Question 13

leishmaniasis is tranmitted through what?

Answer 13

sandflies

Question 14

what kind of pathogen is leishmania

Answer 14

obligated intracellular pathogen

Question 15

2 syndromes caused by leishmania

Answer 15

• Localized cutaneous self-resolving lesion
• Systemic visceral leishaniasis (fatal without treatment)

Question 16

2 cells that leishmaniasis invade

Answer 16

neutrophils and macrophages

Question 17

where do leishmaniasis live

Answer 17

in macrophage phagosomes

Question 18

why does leishmaniasis cause skin inflammation

Answer 18

through tissue damage and sandfly salivary proteins

Question 19

what response does leishmaniasis elicit

Answer 19

CD4+ and Th1response and Th1 delayed hypersensitivity (chronic exposure), INF-gamma secretion, M1like macrophages (iNOS, nitric oxide), eosinophils may promote unprotective Th2

Question 20

describe parasitic worms and a few examples

Answer 20

large, multicellular. NEMATODEs, cestodes, trematodes

Question 21

how do worms contaminate the environement

Answer 21

eggs contaminate food, water and feces

Question 22

are helminths intracellular or extracellular

Answer 22

exclusively extracellular

Question 23

how do helminths enter the host

Answer 23

through internal mucosa

Question 24

why do helminths have limited immune engagement

Answer 24

often do not replicate within host, giving few epitopes

Question 25

do helminths get phagocytozed

Answer 25

no, they are two large to get phagocytosed

Question 26

how do helminths hide from immunity

Answer 26

wrap themselves in host proteins and limit immunity

Question 27

how do helminths get expelled

Answer 27

IgE mediated mast cells and eosinophil degranulation
- release of histamines and leukotrienes that induce muscle contractions and mucus secretion (diarrhea, vomit and coughing)

Question 28

2 ways helminths get expelled

Answer 28

Ig-mediated past cell and eosinophil degranulation and Th2 type responce

Question 29

describe the Th2 type response for expelling helminths

Answer 29

IL-4 production, Th2 cell activation and IgE

Question 30

describe the effective and ineffective mechanism for expelling helminths

Answer 30

Th2 = effective: Includes IgE, mast cell degranulation, influx of eosinophils, antibody dependent cytotoxicity

Th1 = ineffective: macrophages and INF-gamma. Likely inhibited as an invasion mechanism, parasite might survive if this response is activated

Question 31

how are fungal infections aquired

Answer 31

ubiquitous

Question 32

how do fungal infections gain access to the host

Answer 32

via mucosae to extracellular spacesw

Question 33

what causes fungal infections

Answer 33

exogenous or endogenous commensal organisms that become pathogenic

Question 34

what kind of immunity controls most fungal infections

Answer 34

Innate immunity!
- physical barriers
- commensal microbiota. Antibacterial medications may result in yeast infections
- phagocytosis by neutrophils

Question 35

what is key for controlling fungal infections

Answer 35

PRRs: C-type lectin receptors sense cell wall components (B glucans, mannans, chitin),
- TLRs 2,4,9 and complement receptor 3
- Th1 response
- Adaptive immunity

Question 36

what increases susceptibility for fungal infections

Answer 36

Th2 response ??
T cell immunosuppressed patients

Question 37

Describe Neospora caninum

Answer 37

• obligate intracellular parasite
• affects cattle (abortions) and dogs
• domestic dogs are the host

Question 38

describe the balance between Th1 + Th2 response for controlling neosporosis

Answer 38

Th1 responce –> INF-gamma –> control of infection but non viable pregancy because severe inflammation

Th2 response –> IL-4 and IL10 –> uncontrolled infection but viable preganancy

Question 39

what is key for killing neospora

Answer 39

TH1 INF-gamma and macrophages

Question 40

Immune response to intracellular bacteria, protozoa and viruses

Answer 40

Th1-type response

Question 41

Triggered by IL-12 by dendritic cells, macrophages and B cells

Answer 41

Th1-type response

Question 42

Induces pro-inflammatory cytokines including IFNg by T cells and NK cells

Answer 42

TH1-type responce

Question 43

An antibody-stimulating immune response elicited by helminth parasites

Answer 43

Th2-type response

Question 44

expression of IL-4 cytokines

Answer 44

Th2-type responce

Question 45

infiltration of eosinophils and mast cells and IgE production

Answer 45

Th2-type responce