Microbial Toxins

Question 1

define microbial toxin

Answer 1

macromolecular products that cause harm by altering cellular structure or function

Question 2

2 most toxic biological substances

Answer 2

botulinum and tetanus neurotoxins

Question 3

low doses of LPS–>

Answer 3

macrophages, b cells, alternative complement–> fever, inflammation, acute phase reactants and antibodies

Question 4

high doses of LPS

Answer 4

DIC and shock

Question 5

many LPS biological effects are mediated by

Answer 5

cytokines

Question 6

how do toxins facilitate microbe spread and 3 exaples

Answer 6

break down ECM or degrade necrotic debris- hyaluronidase, collagenase, elastase

Question 7

hemolysis or cytolysis how do they cause problems

Answer 7

damage cell membrane

Question 8

pyrogenic exotoxins work ho

Answer 8

stimulate cytokines

Question 9

3 ex of pyogenic exotoxins

Answer 9

erythrogenic toxins of S progenies and enterotoxins and TSS toxin of s. aureus

Question 10

what are superantiens

Answer 10

most POTENT t cell activators that work by binding both MHC II on APCs and specific V beta chains on T cells at a site different from antigen binding site to stimulate excessive cytokine production

Question 11

how does diphtheria toxin and pseudomonas aeruginosa exotoxin A cause problems?

Answer 11

ADP ribotransferases that put a dipthamide on EF2 and inactivate EF2—> inhibit protein synthesis

Question 12

how does Shiga toxins (shigella dysenteriae) and e coli and ricin plant toxin cause problems

Answer 12

RNA Nglycosidases– remove an adenine from 28S RNA of 60S ribosome–> inhibit protein synthesis

Question 13

how do heat labile enterotoxins of V. cholera and e coli work?

Answer 13

ADP ribotransferases that activate the ALPHA SUBUNIT OF GS REGULATORY PROTEIN IN CYCLASE COMPLEX–> increase intracellular cAMP in small intestine–> diarrhea

Question 14

how does pertussis toxin work

Answer 14

ADP ribotransferase that INACTIVATES THE ALPHA SUBUNIT OF Gi REGULATORY PROTEIN to increase intracellular cAMP

Question 15

bacillus anthraces and bordetella pertussis produce what 2 toxins (respectively)

Answer 15

1. anthrax edema factor (EF) and 2. adenylate cyclase toxin

Question 16

how does anthrax EF and adenylate cyclase toxin work

Answer 16

cause intracellular cAMP to increase

Question 17

what does anthrax EF and adenylate cyclase require to work

Answer 17

calmodulin and calcium from TARGET CELLS to activate it

Question 18

antrhax lethal toxin does what

Answer 18

endopeptidase, cleaves many MAP kinase kinase proteins–> inactivates them

Question 19

clostridium difficile toxins a and b work how

Answer 19

inactivates the Rho family GTPases by transferring glucose from UDP-glucose to the Rho GTPases to alter actin cytoskeleton

Question 20

2 toxins inhibit neurotransmitter release- what are they and what do they need

Answer 20

botulinum and are zinc dependent endopeptidases

Question 21

how many antigenic types do you find with botulinum and tetanus toxins

Answer 21

7 and 1 (respectively)

Question 22

how does botulinum toxin cause problems

Answer 22

inhibit AcH release at myoneural junctions leading to flaccid paralysis of skeletal muscles

Question 23

which neurotoxin is used therapeutically

Answer 23

botulinum

Question 24

how does tetanus toxin cause problems

Answer 24

sustained muscular contraction of skeletal muscles by inhibiting release of neurotransmitter from INHIBITORY INTERNEURONS AT SPINAL CORD

Question 25

both neurtotoxins inactivate what

Answer 25

SNARE proteins needed for neuroexocytosis

Question 26

3 SNARE proteins

Answer 26

CAMP, Snap 25 and synthaxin

Question 27

kochs postulates in the version to show that a toxin is implicated in the pathogenesis of an infectious disease

Answer 27

1. purified toxin injected --> same symptoms and signs, 2. antitoxin prevents disease 3. virulence correlates with toxin produced 4. nontoxinogenic mutants don't cause problems and restoring virulence occurs when microbe can produce toxin again

Question 28

molecular version of koch's postulates

Answer 28

1. phenotype is associated with a species or strain, 2. inactivation of virulence gene--> decreased virulence 3.replace mutant gene with WT restores virulence

Question 29

microbial toxins that work intracellularly usually enter by

Answer 29

endocytosis

Question 30

4 things that get into cells and translocate to the right spot in the cell via a translocation domain

Answer 30

diptherai, antrax toxin protective antigen, botulinum, and tetanus

Question 31

4 toxins that get into the cell and do NOT use a translocation domain (use retrograde pathway from endosomes)

Answer 31

shiga, cholera, e. coli heat labile enterotoxin and pertussus