8-2: Microbial Pathogenesis

Question 1

We don’t know about any pathogenic…

Answer 1

Archaea

Question 2

Vast majority of the microbes we interact with are…

Answer 2

Neutral/beneficial

Question 3

What is an infection

Answer 3

Invasion of body by a disease-causing organism. Can result in disease

Question 4

What is a disease

Answer 4

Damage or injury to host organism. Some bacteria cause disease without infection

Question 5

What is a pathogen

Answer 5

an organism that causes disease

Question 6

What is pathogenesis

Answer 6

Mechanism that leads to disease

Question 7

What is virulence

Answer 7

Similar to pathogenesis, used to describe the severity of the disease

Question 8

What is an opportunistic pathogen

Answer 8

Organism that is often non-pathogenic, but becomes pathogen under certain circumstances

Question 9

Symptoms of a bacterial disease are caused by…

Answer 9

Activities of pathogen or immune response to pathogen (fever, rashes, redness, swelling)

Question 10

Major steps in many infections/microbial diseases

Answer 10

Adherence: binding to specific host cells/tissues
Colonization: expanding population
Invasion: gain access to privileged sites
Spread: move beyond site of initial infection

Question 11

What is a mucous membrane

Answer 11

Tightly packed epithelial cell layers covered with a mucous layer (protective)
Lines body access points (airways, oral cavity)

Question 12

What is invasion

Answer 12

Ability of pathogen to enter host cells and/or tissues. Penetrate beyond where microbes usually reside

Question 13

Strategies of invasion

Answer 13

Entering host cells, damaging epithelial layers

Question 14

What is a virulence factor

Answer 14

Molecules produced by a pathogen that contribute to its ability to cause disease

Question 15

Common types of virulence factors (5)

Answer 15

1. Adhesion factors
2. Nutrient acquisition
3. Immune resistance (help pathogen survive immune defense)
4. Immune evasion/disruption
5. Extracellular enzymes, protein secretion systems/effectors and toxins

Question 16

Describe adherence as a virulence factor

Answer 16

Microbes typically target specific cell or tissue type, adherence to specific receptors on those cells is key
Provides foothold, facilitates interaction/invasion of host cells

Question 17

Examples of adhesins

Answer 17

Pili, fimbriae, surface proteins, capsules

Question 18

Adherence receptors:

Answer 18

Glycoprotein, glycolipids

Question 19

How do pathogens evade the immune system

Answer 19

Hide inside cells
Produce capsule to hide surface antigens (prevent immune detection)
Modify antigens e.g. PAMPs such as LPS detected by immune system

Question 20

What are extracellular enzymes

Answer 20

Secreted/surface enzymes that promote virulence

Question 21

How do extracellular enzymes promote virulence

Answer 21

Free up nutrients, damage host cells, inactivate immune cell mechanisms, disrupt barriers to enable invasion

Question 22

Example of secretion system for virulence

Answer 22

Type III secretion system (T3SS)

Question 23

How do T3SS work

Answer 23

Inject effector proteins into host cells
effectors have specific target to manipulate host cell biology

Question 24

What are exotoxins

Answer 24

Secreted protein toxins, similar to bacteriocins

Question 25

e.g. of bacterial toxin

Answer 25

alpha-toxin from S. aureus

Question 26

What are AB-type toxins

Answer 26

subunit A exerts biological effect (modify/degrade specific molecules)
subunit B binds host cell receptor to mediate uptake

Question 27

What kind of toxin is botulinum toxin

Answer 27

AB-type

Question 28

What produces botulinum toxin

Answer 28

Clostridium botulinum

Question 29

B subunit in botulinum toxin targets

Answer 29

motor neurons

Question 30

Subunit A in botulinum is

Answer 30

a protease, cleaves proteins required to release the neurotransmitter acetylcholine

Question 31

Botulinum toxin leads to

Answer 31

Muscle paralysis

Question 32

How are toxins therapeutic

Answer 32

Inactivated toxins as vaccines
Treat non-bacterial diseases
Botox (botulinum toxin) = helps migraines, cerebral palsy

Question 33

How are toxins and secretion systems different

Answer 33

Toxins can diffuse/spread to distant cells
SS need direct contact
Toxins can be more potent

Question 34

Three types of plague

Answer 34

Bubonic (lymph nodes), pneumonic (lungs), septicemic (bloodstream)

Question 35

Virulence factors of yersinia pestis

Answer 35

T3SS injects effector proteins into immune cells
F1 capsule inhibits uptake of Y pestis by immune system, inhibits surface antigen detection