0113100830 - Mfm Ii - Virulence Factors (Biel)

Front 1

What are the four ways that bacteria can avoid phagocytes?

Back 1

1) avoid detection
2) lyse phagocytes
3) inhibit phagocytes
4) prevent intracellular killing

Front 2

How do microbes avoid detection by phagocytes?

Back 2

1) capsule (Strep. pyogenes) is not recognized by phagocytes because capsule is made of hyaluronic acid, so looks like connective tissue
2) coagulase (Staph. aureus) converts fibrinogen to fibrin which walls off microbe from phagocyte

Front 3

How do microbes avoid the immune system by lysis of phagocytes?

Back 3

1) streptolysin (Strep. pyogenes)
2) alpha-toxin (C. perfringens)

Front 4

How do microbes avoid the immune system by preventing intracellular killing?

Back 4

1) preventing fusion of phagocyte w/ lysosome (Myco. tuberculosis)
2) resistance to lysosomal enzymes (Staph. aureus)
3) dissolve phagocyte membrane and escape (Rickettsia)

Front 5

What three methods have bacterium devised against antibodies and complement?

Back 5

1) Antigenic variation
2) Inactivation of antibodies
3) Inactivation of complement

Front 6

How do bacterium avoid the immune system by antigenic variation?

Back 6

making different antigenic structures (like pili) that the body does not have antibodies for

Front 7

How do bacterium avoid the immune system by inactivating antibodies?

Back 7

they can prevent Ab binding or actually destroy Abs

Front 8

How do bacterium avoid the immune system by inactivating complement?

Back 8

some microbes can prevent complement binding by masking; others interrupt the complement cascade even after binding occurs.

Front 9

How do capsules act as virulence factors?

Back 9

1) prevent correct function of complement
2) prevent phagocyte-mediated destruction by hiding cell in "mask"
3) promoting microbe adherence to body structures

So in general, capsules (3) promote colonization and invasion and (1,2) help bacterium avoid host immune defense.

Front 10

How does the M Protein act as a virulence factor?

Back 10

produced by Strep. pyogenes that attaches to the cytoplasmis membrane and extends through the cell wall. It is a fibril adhesin to
1) promote attachment to oropharynx,
2) it prevents opsonization (stopping complement and phagocytosis),
3) and provides antigenic variation of this fibril.

Front 11

What 4 specific bacterial generated factors help spread infection?

Back 11

1) fermentation
2) degradataive enzymes
3) endotoxin
4) exotoxin

Front 12

How do degradative enzymes help spread infection?

Back 12

proteases, lipases, hyaluronidases and collagenases destroy tissue and provide nutrients and help bacterium stpread.

Front 13

How do endotoxins help bacterium spread infection?

Back 13

These stay attached to the cell and only work in the immediate vicinity of the bacterium.

Endotoxin is Lipid A from Gram(-). When Gram (-) bacterium infects, large amounts of Lipid A are released they cause septic shock.

Gram (+) don't have an outer membrane, so no Lipid A, so they release a much weaker peptidoglycan, teichoic acid, and lipoteichoic acids.

Front 14

What are the symptoms of septic shock?

Back 14

fever
diarrhea
vomiting
shock

Front 15

What are exotoxins?

Back 15

proteins secreted by bacteria and damage or kill host cells. they are produced in the cell and secreted into the environment.

Front 16

What are the three classes of exotoxins?

Back 16

Type 1: act on cytoplasmic membrane of host and cause changes within the cell
Type 2: damage host cytoplasmic membrane
Type 3: most common, these move into the cell and cause problems within the cell directly, these are A-B type

Front 17

Type 1 exotoxins - Heat Stable Toxin (STa) of E. coli

Back 17

binds to guanylate cylclase on cytoplasmic membraen of host which increases cGMP levels in the cell. This causes water and electrolytes to be secreted from the host cell -> diarrhea.

Front 18

How is the ST enterotoxin transferred?

Back 18

ST enterotoxin is carried on a plasmic and can be transferred via conjugation

Front 19

What are super antigens?

Back 19

they bind the T-cell receptor on MHC II APCs activating up to 20% of T cell sin the body resulting in a TON of cytokines inducing fever, diarrhea, vomiting, shock.

Front 20

What are two examples of super antigens?

Back 20

Staph. aureus TSST-1 (toxic shock syndrom toxin) and Strep pyogenes SPEs (Strep pyrogenic exotoxins) are both examples

Front 21

Whare are the 4 pore forming Type 2 Exotoxins?

Back 21

1) alpha-toxin of Staph. aureus
2) Cholesterol-binding cytolysins made by Gram (+) Strep, Listeria, Clostridium, Bacillus
3) RTX (repeat-in-toxin) found in Gram(-) E. coli causing death by osmotic lysis or apoptosis
4) Phospholipases disrupt the phospholipid portion of the membrane by producing phospholipase C - Clostridium perfringes alpha-toxin and Staph. aureus beta-hemolysin

Front 22

AB exotoxins subunit properties

Back 22

B subunit binds to cell surface receptor
A subunit enters the cell

Front 23

What are the three subunits of Type 3 AB exotoxins?

Back 23

1) protein inhibitors
2) neutortoxins
3) cAMP inducers/increasers

Front 24

There are the 4 examples of protein inhibiting AB exotoxins. What are the qualities of the Diphtheria toxin?

Back 24

Corynebacterium diphtheria produce Diphtheria toxin located on a phage which inactivates EF-2 by ADP-robosylation. all euk cells are targeted, but myocardial an dperipheral nerve cells are primary targets.

Front 25

There are the 4 examples of protein inhibiting AB exotoxins. What are the qualities of the Exotoxin A?

Back 25

Pseudomonas aeruginosa produce Exotoxin A located in the chromosome which inactivates EF-2 by ADP-ribosylation. all euk cells are targeted.

Front 26

There are the 4 examples of protein inhibiting AB exotoxins. What are the qualities of the Shiga toxin (Stx)?

Back 26

Shigella dysenteriae produce Shiga toxin located in the chromosome which interferes with 60s ribosomal subunit. interstinal epithelium are the primary target which causes diarrhea.

Front 27

There are the 4 examples of protein inhibiting AB exotoxins. What are the qualities of the Shiga (Stx1) and Shiga-like (Stx2) toxin?

Back 27

E. coli (EHEC, STEC) produce Shiga and Shiga-like toxins located on a bacteriophage which interferes with 60s ribosomal subunit. interstinal epithelium are the primary target which causes diarrhea.

Front 28

What is the difference between Stx1, Stx2 and Stx?

Back 28

it just depends on what organism produces it:
Stx (shiga) - Shigella
Stx1 (shiga) - E. coli
Stx2 (shiga-like) - E. coli

Front 29

What is EHEC and STEC?

Back 29

EHEC - enterohermorrhagic E. coli
STEC - Shiga-toxin producing E. coli

Front 30

Stx2 is associated with what specific syndrome?

Back 30

HUS (hemolytic uremic syndrome) which can result in acute renal failure.

Front 31

What are the two neurotoxins in the AB Type 3 exotoxins?

Back 31

1) Tetanus toxin
2) Botulinum toxin

Front 32

There are the 2 examples of neurotoxin AB exotoxins. What are the qualities of tetanus toxin?

Back 32

Clostridium tetani produce Tetanus toxin located on a plasmid which blocks the release of inhibitory glycine and GABA causing uncontrolled muscle spasm. They target the neuromuscular junction of inhibitory motor neurons.

Front 33

There are the 2 examples of neurotoxin AB exotoxins. What are the qualities of Botulinum toxin?

Back 33

Clostridium botulinum produces the Botulinum toxin located on a bacteriophage which blocks the release of acetylcholine preventing muscle contraction. Neuromuscular junction of stimulatory motor neurons.

Front 34

What is significant about adult botulism?

Back 34

it is not an infection. it is caused by ingesting the botulism toxin, so antibiotics don't do crap.

Front 35

There are the 4 examples of cAMP inducing AB exotoxins. What are the qualities of Heat Labile toxin (LT)?

Back 35

ETEC E. coli produce the Heat Labile toxin (LT) located on a plasmid which causes adenylate cylcase stimulation by adding ADP-ribosyl group causing watery diarrhea. Epithelial cells of the small intestine are targets.

Front 36

What are the 4 examples of cAMP inducing AB exotoxins?

Back 36

1) Heat Labile toxin (LT)
2) Cholera toxin
3) Anthrax toxin EF, LF, PA subunits
4) Pertussis toxin

Front 37

There are the 4 examples of cAMP inducing AB exotoxins. What are the qualities of Cholera toxin?

Back 37

Vibrio cholerae produces the Cholera toxin located on a bacteriophage causes adenylate cylcase stimulation by adding ADP-ribosyl group causing watery diarrhea. Epithelial cells of the small intestine are targets. Deadly because of rapid dehydration.

Front 38

There are the 4 examples of cAMP inducing AB exotoxins. What are the qualities of Anthrax toxin?

Back 38

Acillus anthracis produces Anthrax toxin located on a plasmid which causes adema, local cell death. All euk cells are targeted.

Front 39

What are the three subunits of the anthrax toxin and what are their purposes?

Back 39

EF (edema factor) is an adenylate cyclase -> water excretion -> edema in tissue
LF (lethal factor) is a protease and causes cell death
PA (protective antigen)

Front 40

There are the 4 examples of cAMP inducing AB exotoxins. What are the qualities of Pertussis toxin?

Back 40

bordetella pertussis produces the pertussis toxin located on the chromosome which stimulates adenylate cyclase by inhibiting the Gi inhibitor protein which causes water loss into peripheral spaces of ciliated epithelial cells -> whooping cough.

Front 41

What are Type III secreted cytotoxins?

Back 41

The second class of Type 3 exotoxins that are produced within the bacterium and injected directly into the host cell. This is used by some Gram(-) bacterium.

Front 42

What are 3 examples of Type 3 secreted cytotoxins?

Back 42

Yersinia injects proteins -> apoptosis
Pseudomonas aeruginosa injects proteins -> phogocytic inhibition
Salmonella enterica causes epithelial cells to engulf bacteria to allow endocytosis

Front 43

How do Gram(+) secrete exotoxins and degredative enzymes?

Back 43

1) protein is made
2) protein is pushed out of protein
3) signal sequence is cleaved off of protein allowing for protein folding

Front 44

How do Gram(-) secrete exotoxins and degredative enzymes? There are three types of transfer mechanisms.

Back 44

Type I - cytoplasmic and outer membrane transport happens in one step
Type II - cytoplasmic membrane transport occurs, then separately the outer membrane transport occurs
Type III - cytoplasmic membrane, outer membrane, and host plasma membrane are all transported across at the same time.

Front 45

Toxoid

Back 45

inactivated toxin that is used to provide a non-symptom producing antigen for the body to use to make Abs

Front 46

What toxins are protected against via a toxoid?

Back 46

1) Diphtheria - Corynebacterium diphtheriae
2) Tetanus toxin - Clostridium tetani

Front 47

What is the treatment of tetanus?

Back 47

1) clean wound
2) give antibiotics to kill vegetative cells
3) vaccinate with tetanus toxoid to make Abs to toxin which inactivates toxin not bound to nerve cells.