Lecture 16- Immune Response to Bacteria/Fungi

Question 2

Pathogen

Answer 2

Bacterium or virus or other microorganism that can cause disease

Question 3

Opportunistic pathogen

Answer 3

Bacterium, virus or other microorganism that can cause disease in people with impaired immunity but not in healthy individuals

Question 4

Being a pathogen means to evade ____

Answer 4

Innate immunity

Question 5

What is an example of a non-pathogen that is resident of mammalian microbiotia

Answer 5

E. Coli K12

Question 6

What can enteropathogenic and enterotoxigenic eschirichia coli cause

Answer 6

Diarrheal diseases in dogs and cats

Question 7

What body surface has the most bacterial cells

Answer 7

Colon- 10^12

Question 8

inflammatory bowl disease is a ____ response to microbiota

Answer 8

Adaptive immune response

Question 9

How does the immune system respond to non-pathogens

Answer 9

Complement, phagocytosis, adaptive response to microbiota

Question 10

How do pathogens evade the immune system

Answer 10

Antigenic variation, antigenic drift, molecular mimicry, and virulence factors

Question 11

What is antigenic variation

Answer 11

Change in H/N molecules

Question 12

What is an example of antigenic drift with Salmonella

Answer 12

Change in arrangement of promoters leads to differential expression of flagellin protein in salmonella

Facing one way we have repressor citrates so no salmonella, but undergo DNA inversion can turn off repressor and activate salmonella

Question 13

How does Pili evade immune system

Answer 13

Highly antigenic carries 10-20 silent promoters

Question 14

What is antigenic drift

Answer 14

Natural mutations over time lead to changes in structure of proteins that may be targeted by antibodies

Question 15

what is molecular mimicry

Answer 15

Sequence similarities between self and virus

Can result in lack of antibody response to antigen and cross-responsiveness

Question 16

How is Lyme a example of virulence factor

Answer 16

Resists complement mediated phagocytosis by producing osp proteins that binds Factor H. Acts like C3b binding factor H which causes inactivation of complement

Question 17

How does a capsule evade the immune system

Answer 17

Inhibits phagocytosis

Important for extracellular bacteria

Question 18

IgA proteases

Answer 18

Cleave IgA at hinge making ineffective can’t act at mucosal surfaces

Question 19

Why is sialyation of LPS bad

Answer 19

Salic acid is on host cells not bacteria so LPS is on gram - bacteria can add Salic acid and fake being host cell

Question 20

What does listeria monocytogenes cause

Answer 20

Gastroenteritis

Question 21

What does listeria monocytogenes produce

Answer 21

Listeria lysin O or LLO that degrades phagosome and therefore replicates in cytoplasm and hijacks host cell and uses act A to propel itself

Question 22

What is the innate immune response to intracellular bacteria

Answer 22

Phagocytosis and NK cell activity

Question 23

Macrophages response to intracellular bacteria

Answer 23

Macrophages secrete IL-12 and IL-15 to recruit NK cells, NK cells will proliferate and secrete INF-y and will bind to macrophages to tell them to increase phagocytosis and release inflammatory cytokines

Question 24

When will NK cell target foreign invader

Answer 24

Downregulation of MHC I

Question 25

What is the adaptive response to intracellular bacteria

Answer 25

Cell mediated immunity, IL-12 stimulates TH1 response resulting in INF-y and expression of CD40L to activate macrophages

Question 26

How do CD8+ T Cells respond to intracellular bacteria

Answer 26

Kill bacteria displaying on MHC I molecules via Perforin and granzymes

Question 27

How do antibodies respond to intracellular bacteria

Answer 27

They play a minor role but can use ADCC- antibody’s bind target cell, FC receptors on NK cell recognize bound antibodies, crosslinking activates NK cell to release toxic granules and kill cell

Question 28

How do intracellular bacteria evade immune system

Answer 28

Escape the phagosome, prevent phagosome-lysosome fusion and resistant to lysosomal enzymes

Question 29

What are the mechanisms of pathogenesis of extracellular bacteria

Answer 29

Release toxins endotoxins and exotoxins

Question 30

What are endotoxins and example

Answer 30

LPS- activator of macrophages causes release of cytokines and activates alternative complement

Question 31

What are exotoxins and exmaple

Answer 31

Either stimulate cytokine release or are cytotoxic to other cells PMT in atrophic rhinitis in swine disrupts cell signaling leads to bone resorption and disrupted bone formation by messing with GPCR’s and disrupting GTP—> GDP and cell will die of apoptosis

Question 32

What is the innate response to extracellular bacteria

Answer 32

Physical barriers, antimicrobial peptides- lysozymes and defensive

Question 33

What is the adaptive response to extracellular bacteria

Answer 33

Antibodies

Question 34

How do fungal pathogens evade immune system

Answer 34

Persistence within phagocytes, inflammation, CTL activity

Question 35

What type of PRRs do macrophages and dendritic cells express to recognize fungal cell wall components

Answer 35

TLR’s and Dectins

Question 36

What is the adaptive immune response to fungal pathogens

Answer 36

Cell mediated stimulated by cytokines from dendritic cells

Question 37

Dendritic cell recognizes a fungal pathogen and results in activation of innate effector cells and _____

Answer 37

Generation of TH1/Th17 adaptive responses

Question 38

What is the adaptive immune response to intracellular fungi

Answer 38

TH1 and CTL’s

Question 39

What is the response of the adaptive immune system to extracellular fungi

Answer 39

Th17- stimulate neutrophils

Question 40

What are some fungal pathogen evasion tactics

Answer 40

Biofilm to resist phagocytosis, mask antigens, capsules, obtain nutrients like iron and zinc, inactive antimicrobial peptides