Pathogens

Question 1

do all strains of a species have the same ability to cause disease?

Answer 1

no

Question 2

pathogen usually identified by the set of ________ that it carries and expresses

Answer 2

virulence genes

Question 3

virulence

Answer 3

ability to cause damage to the host

-depends on virulence factors

Question 4

mutually exclusive

Answer 4

when two outcomes can’t happen or be true at the same time

ex) coin toss

Question 5

invasivness definition and what different virulence factors does the pathogen use?

Answer 5

the ability of the microorganism to become established in the host
uses different virulences factors:
- adhesions capsules
-enzymes
-invasions
-type 3 secretion system and type 4 (T3SS and T$SS)

Question 6

toxigenicity definition

Answer 6

the capacity of the microogrganism to produce substances known as toxins that damage specific tissues of the host

Question 7

two basic features of virulence (that are NOT mutually exclusive)

Answer 7

toxigenity and invasivness

Question 8

what are Adhesins?

Answer 8

prompt specific attachment to the host cell surfaces

Question 9

what adhesions mediate close attachment?

Answer 9

fibril adhesins (glycolic/lipo proteins )

Question 10

what adhesion mediate loose attachment?

Answer 10

Fimbriae/Pili

Question 11

Capsule

Answer 11

produced by some bacterial pathogens

• prevent the pathogen from being destroyed by the host immune cells (phagocytes)
• also mediates attachment to the host cells
• essential virulent factor for some bacterial species
• NOT only a virulent factor( non-pathogenic bacteria produce it too sometimes)

Question 12

which 2 exotoxin enzymes have an effect on the ECM? which 1 on the host cell membrane

Answer 12

Hyaluronidase
Collagenase
host cell membrane - lecithinase

Question 13

Hyaluronidase

Hya-lur-on-i-dase

Answer 13

degrades hyaluronic acid, a sticky polysaccharide that holds host cells together. Staphylococci and streptococci and clostridia

Question 14

Collagenase

Answer 14

degaraades collagen present in connective tissue. Clostridia

Question 15

Lecithinase

Answer 15

degrades lecithin in cell membrane and casques the lysis of red blood cells and destroys tissue cells

Question 16

Gas gangrene

Answer 16

Clostridium perfringens (strict anaerobe) 
infection in deep wounds

• uses lecithinase to lyse host cells, collagenase and hyaluronidase to destroy ECM
• gross stitches picture on slide

Question 17

Hyaluronidase producer (such as streptococcus progenies) attaches to _____.

Answer 17

epithelia

Question 18

Hemolysins

Answer 18

• cause lysis of RBC and other cell types
• some are enzymes (lecithinase and phospholipase)
• some are cytolysis (pore-forming).
• produces by a great variety of bacteria

Question 19

Leucocidin

Answer 19

causes lysis of leucocytes- WBC

- produced by staphylococci, streptococci and few other gram- neg

Question 20

Coagulase

Answer 20

produced by virulent staphylococci, causes insoluble fibrin to be deposited on bacterial cells and protects/blocks bacteria from the immune system
- invisible cloak

Question 21

Invasins

Answer 21

invasive surface proteins or injected proteins that allow microgansims (pathogens) to enter the cells (invade host)

Question 22

Which bacteria use invasin proteins

Answer 22

mycobacterium, salmonella, listeria, chlamydia

Question 23

Ways to modify the properties of the host cells

Answer 23

• block phagosome maturation (block digestion)
• increase size of the vacuole
• acquire nutrients
• block detection of intracellular infection and response (block host response)

Question 24

type 3 secretion systems (T3SS)

Answer 24

• also called injectisome
  large number of gram neg use these systems
• T3SS forms a channel through the bacterial cytoplasmic membrane, the periplasm, the outer membrane and the host cell membrane so that bacterial proteins can be injected into the host cell cytosol

Question 25

T4SS

Answer 25

similar to T3SS but absence of needle like structure

Question 26

timeline for pathogenicity

Answer 26

exposure--> adherence--> invasion through epithelium--> multiplication--> toxicity and invasiveness (further growth and into distant sites)--> tissue or systemic damage

Question 27

Toxigenicity

Answer 27

micro org to produce toxins that cause damage o specific tissues

Question 28

are extracellular enzymes toxins?

Answer 28

yes, anything that cause damage to the host cell

Question 29

toxins not always associated with high virulence. other factors that can damage host include

Answer 29

large number of pathogens | damage by hosts own immune system

Question 30

2 types of bacterial pathogens

Answer 30

infectious disease- result from pathogens own growth and multiplying intoxications- result from pathogens toxins produced (food poisoning)

Question 31

2 types of toxins

Answer 31

exotoxins- excreted int the environment | endotoxins- part of the bacterial pathogen (internal)

Question 32

Exotoxins

Answer 32

soluble, secreted or release when the organism is lysed, usually proteins and heat liable (destroyed by heat) - highly immunogenic (antibody response inactivates exotoxins) -extremely potent categorized by their target (neurotoxins, enterotoxins eat.)

Question 33

AB toxins- what are the 2 subunits

Answer 33

``` A= enzymatic subunit B= binding/cell entry ```

Question 34

Subunit A's job

Answer 34

modifies a target inside the host cell leading to damage to the host " the actual toxic part"

Question 35

subunit B

Answer 35

binds to cell receptors providing tissue/cell type specificity " the binding part" B for binding

Question 36

Clostridium botulinum

Answer 36

is an AB toxin/neuro toxin that blocks acetylcholine release in neuromuscular junction - leads to flaccid paralysis - effects human cattle horses and ducks - BOTOX - reduces wrinkle

Question 37

``` AB toxin (Botulinum toxin) normal state vs with botulism ```

Answer 37

normal- acetylcholine induces contraction of muscle fibers (think contracted is like wrinkles) with botulism --> blocks release of Acetylcholine, inhibits contraction (flaccid)

Question 38

AB toxin: Tetanus toxin

Answer 38

found in soil infects deep puncture wounds and produces toxin TeNT which causes spastic paralysis; bowed spine, locked jaw (weird picture on slide )

Question 39

Tetanus toxin normal vs with toxin

Answer 39

normal--> Glycine release from inhibitory interneurons stop acetylcholine release and allowing relaxation of muscles with tetanus toxin--> prevents the release of glycine and therefore acetylcholine is released and muscles contract

Question 40

AB5 Toxin: Cholera toxin

Answer 40

B binds to intestinal cells A activates adenylate cyclase, produces cAMP - blocks Na+ uptake, neg ions travel in to balance and water moves with the ions

Question 41

explain how cholera toxin produces excess water in intestine

Answer 41

normally Na+ moves from intestine into blood stream with toxin--> A subunit binds to adenylyl cyclase and this creates lots of cAMP which blocks Na+ uptake. because of surplus in + charge in intestine, CL- and HCO2- move out and with the ion movement water also moves out

Question 42

Endotoxins

Answer 42

Are apart of the toxin, as opposed to exotoxin which gets released from within the pathogen lipid A of LPS (example) - released during lysis -heat stable, cannot be activated - weakly immunogenic- (no antibodies are produced) -BUT very effective activator of the immune system - produce general systemic effects- fever-- septic shock

Question 43

key points of endotoxins

Answer 43

Main point is that they are HEAT STABLE and very effective activators of immune systems- fever and general systemic effects, BUT weakly immunogenic (no antibodies produced) - can't make vaccines bc can't inactivated with heat (they are heat stable)

Question 44

Vaccines against toxins

Answer 44

exotoxins are highly antigenic meaning that they stimulate the host defese to produce antibodies that can neutralize them so vaccines can imitate these BUT endotoxins cannot be inactivated by heat and so no vaccine! -toxins are first inactivated by heat or formaldehyde--> toxoids (no longer toxic but still antigenic)

Question 45

toxoids

Answer 45

no longer toxic but still antigenic, can be used in a vaccine

Question 46

Acetylcholin causes

Answer 46

contracted muscles and winkles so with botulism--> inhibits the release of acteltycholine--> flaccid with tetanus--> prevents the release of glycine, which allows more acetylcholing--> stiff

Question 47

Diphtheria

Answer 47

AB, inhibits protein synthesis