Pathogenesis: Adhesion

Question 1

Virulence Factors purpose

Answer 1

• Involved in Adhesion of a pathogen
• Involved in Invasion of a host cell
• Involved in Evasion of the immune system
• Involved in host damage caused by a pathogen

Question 2

Steps in the infectious process

Answer 2

1. Adhesion/Entry
2. Invasion/Local or General Spread 3. Multiplication
3. Evasion
4. Damage (pathology/disease)
5. Transmission (Shedding)

Question 3

Outcome of infectious disease

Answer 3

• Host immunity
• Pathogen virulence

Question 4

Commensals

Answer 4

normal microbiota

Question 5

Opportunists

Answer 5

bacteria that affects immunocompromised hosts

Question 6

Primary pathogen

Answer 6

opposite of opportunistic, can infect healthy host

Question 7

virulent factors

Answer 7

• motility via flagella
• adherence via
  
  • pili
  • non-pilus adhesins

Question 8

pili functions

Answer 8

• Pili enable some organisms to adhere to receptors on target host cells and thus colonize and resist flushing by the body
• other functions
  
  • DNA transfer, phage binding, biofilm formation, cell aggregation and twitching motility

Question 9

What are pili?

Answer 9

thin, protein tubes originating from the cytoplasmic membrane and are found in many Gram-negative bacteria but not in many Gram-positive bacteria

Question 10

How do pili adhere?

Answer 10

• Both bacteria and the host cells have a negative surface charge leading to electrostatic repulsion
• The electrostatic repulsion is cancelled out by the protein shaft called pilin and adhesive tip

Question 11

Pili are classified by what?

Answer 11

their structure and assembly mechanisms

Question 12

Type I pili species

Answer 12

EPEC (enteropathogenic E. coli)

Question 13

Type I pili adhesion receptors

Answer 13

glycoproteins and glycolipids (D-mannose component)

Question 14

Type I pili gene organization

Answer 14

operon

Question 15

Type I pili functions

Answer 15

• host-tissue adhesion
• co-aggregation
• immunomodulation
• biosensor and biofilm formation

Question 16

Type IV pili species

Answer 16

E. coli , Salmonella enterica, Pseudomonas aeruginosa, Neisseria meningitides, Neisseria, gonorrheae, Legionella pneumophila, Vibrio cholerae

Question 17

Type IV pili adhesion receptors

Answer 17

• CD46
• glycolipids
• C4BP

Question 18

Type IV pili gene organization

Answer 18

pathogenicity island

Question 19

Type IV pili functions

Answer 19

• host-tissue adhesion
• co-aggregation
• immunomodulation
• motility
• DNA uptake

Question 20

What are non-pilus adhesions?

Answer 20

Surface proteins found in the cell wall of various bacteria that bind to specific receptor molecules on the surface of host cells

Question 21

non-pilus adhesins examples

Answer 21

• Streptococcus pyogenes
  
  • Lipoteichoic acid, Protrein F, M protein (bind to fibronectin, a common protein on epithelial cells)
• Neisseria gonorrheae:
  
  • Opa protein that enables the bacterium to make a more intimate contact with the host cell after it first adheres with its pili
• Staphylococcus aureus
  
  • uses protein A as an adhesin

Question 22

Facultative intracellular pathogens examples

Answer 22

Salmonella, Shigella, Yersinia

Question 23

Obligate intracellular pathogens examples

Answer 23

Rickettsia, Chlamydia, Coxiella

Question 24

Extracellular pathogens examples

Answer 24

Vibrio cholerae, Pseudomonas, enterotoxigenic E. coli