Lecture 6.1: Bacterial Virulence

Question 1

do bacteria always act as pathogens deliberately?

Answer 1

no, it can be inadvertent

Question 2

infection

Answer 2

successful invasion of an animal/plant by a pathogen

Question 3

disease

Answer 3

condition of unrest / discomfort

injury to host that . impairs function

Question 4

virulence factors

Answer 4

traits evolved to promote disease

Question 5

what are some examples of virulence factors?

Answer 5

flagella, pili, capsule

Question 6

E. coli is responsible for what types of infections?

Answer 6

hamburger disease, UTI, diarrheal disease such as Montosmo’s revenge

Question 7

how can E. coli be part of the normal flora and be so dangerous?

Answer 7

some have evolved to be virulent by genetic transfer

Question 8

pathogenesis

Answer 8

creation of pathology diseased state

Question 9

a major strategy of intracellular pathogens is to alter __

Answer 9

alter host signalling in a subtle, but significant way to promote bacterial survival

Question 10

“virulence factors” was coined by

Answer 10

Stanley Falkow

Question 11

Falkow stated that there must be a ___ that causes a bacteria to be pathogenic and that if ___, its virulence would be lost/reduced and if returned ___

Answer 11

gene; removed, virulence would be restored

Question 12

are amino acid biosynthesis genes virulence factors?

Answer 12

no, unless it must be made while in host

Question 13

give 3 traditional virulence factors

Answer 13

extracellular enzymes, exotoxins, endotoxins

Question 14

function of extracellular enzymes

Answer 14

function outside the cell to damage host cell/tissue and can promote colonization/spreading

Question 15

function of exotoxins

Answer 15

subversive functions on host that are very deliberate and specific

Question 16

what are exotoxins?

Answer 16

proteins that are secreted

Question 17

what are endotoxins?

Answer 17

bacterial products that typically have functions for bacterial survival, but can still result in diseased state for the host

Question 18

examples of endotoxins

Answer 18

LTA and LPS

Question 19

endotoxins can cause:

Answer 19

inflammation, haemorrhaging and damage to host

Question 20

effects of endotoxins are more acute with greater number (T/F)

Answer 20

true

Question 21

extracellualr enzymes are bacterial secreted ___ and ___

Answer 21

lipases and proteases

Question 22

extracellular enzymes target___ and alter ___ and cause__-

Answer 22

surface lipids and proteins; cellular receptors; cell and tissue damage

Question 23

exotoxins are usually ___ proteins that have ___ activity on host cells

Answer 23

soluble; cytotoxic

Question 24

can exotoxins have activity even without infection or colonization?

Answer 24

yes

Question 25

the A subunit is a ___ composed of ___

Answer 25

heterodimer; A1 and A2

Question 26

what is the function of the A1 subunit?

Answer 26

ADP ribolysing activity modifies a host protein, blocking its function

Question 27

what is the function of the A2 subunit?

Answer 27

alpha helix that sometimes requires activation by host cell protein

Question 28

the B subunit is a ___ that binds to host cell ___ and functions by targeting specific ___

Answer 28

homopentamer; receptor (glycoprotein); cells

Question 29

many AB toxins function by ___, specifically by inhibiting ___

Answer 29

blocking cell activity; protein synthesis

Question 30

do all bacteria require a host to survive?

Answer 30

no

Question 31

pathogen

Answer 31

organism that causes disease

Question 32

proteases ____ host proteins and make them inactive

Answer 32

cleave

Question 33

virulence factors help infect, colonize, hide, and resist immune attacks by ___

Answer 33

subverting host cellular functions

Question 34

Falkow’s concept of virulence factors mirrors ___

Answer 34

Koch’s postulates

Question 35

give an example of an extracellular enzyme involved with damaging CF lung

Answer 35

Pseudomonas aeruginosa

Question 36

give three examples of exotoxins

Answer 36

clostridium botulinium, diptheria toxin, shiga toxin