Bordetella pertussis

Question 1

Describe the physical features of B. pertussis.

Answer 1

• small (1x10^-3 micrometers)
• gram negative
• coccobacilli

Question 2

How does B. pertussis interact with oxygen (areobe, anareobe… etc)?

Answer 2

It is a strict aerobe.

Question 3

How is B. pertussis detected?

Answer 3

• growth in 3-5 days after first contact
• direct flourescent Mab
• PCR

Question 4

What is direct flourescent Mab?

Answer 4

A monoclonal antibody directed against a unique antigen on the organism is conjugated to a fluorescent marker that can be seen with a fluorescent microscope.

Question 5

What does B. pertussis cause?

Answer 5

Whooping cough

Question 6

What population of people are most affected by whooping cough?

Answer 6

mostly children

Question 7

Where does B. pertussis normally infect people to cause whooping cough?

Answer 7

The upper respiratory tract’s ciliated cells in the epithelium as it is an obligate areobe so it needs oxygen for growth.

Question 8

What are the stages of whooping cough?

Answer 8

1. Catarrhal stage (5-10 days of cold like sysmptoms)
2. Paroxysmal stage ( 1-2 weeks of sudden fits of severe and rapid coughing; the infected person will run out of air and stop coughing to suck air into their lungs causing the whoopng sound)
3. Convalescent stage ( 2 weeks to several months where paroxysms decrease and the immune system is active)

Question 9

What are the 5 components of the current aP (acellular pertussis) vaccine?

Answer 9

• Pertussis toxin (PT)
• Pertactin (Prn): outer membrane protein
• Filamentous hemagglutinin (FHA)
• 2 types of fimbriae (Fim2 and Fim3)

Question 10

Who is immunized against whooping cough in Alberta?

Answer 10

• children at 2, 4, and 6 months then boosters at 18 months, kindergarden and grade 9
• pregnant women

Question 11

Describe the structure of Pertussis toxin (PT).

Answer 11

• an unusual A-B5 toxin
• has 1 A subunit (S1)
• has 4 B subunits (S2, S3, 2xS4 and S5)

Question 12

What does the B subunits do on the pertussis toxin?

Answer 12

binds sugar on the receptor and is endocytosed and is then retrograde transported.

Question 13

How does pertussis toxin (PT) work?

Answer 13

S1 ADP-ribosylates the GTP-binding protein so that the adenylate cyclase (AC) is locked into an active state and cAMP production increases. Uncontrolled cAMP production causes fluid secretion in the lungs and exacerbates symptoms (as you want to cough up the fluid)

Question 14

Pertactin (Prn)

Answer 14

• an outer membrane protein that is a TVSS (type 5 SS)
• Binds B. pertussis to host cells: acts as an adhesin, facilitating colonization of cliated respiratory epithelium (RGD loop binds integrin)

Question 15

Filamentous hemagglutinin (FHA)

Answer 15

• 220 kD surface rod-like protein (not a pilus)
• an adhesin that binds sulfated glycolipids on ciliated cells

Question 16

Fimbriae

Answer 16

• pili in B. pertussis
• 2 types: Fim2 and Fim3

Question 17

Adenylate Cyclase Toxin (ACT or CyaA)

Answer 17

• encoded by cyaA
• secreted by T1SS
• bifunctional enxyme: N-terminal adenylate cyclase activity (increases cAMP level) and C-terminal PTX repeat domain that binds target cells and forms pores
• inhibits several immune cell phenotypes

Question 18

Tracheal cytotoxin (TCT)

Answer 18

• A peptidoglycan recycling intermediate (2 sugars and pentapeptide)
• inhibits cilia beating and causes exrusion of ciliated cells (pro-inflammatory cytokine production)
• Death of ciliated cells may contribute to paroxysmal cough

Question 19

What 2 stable phenotypic forms can B. pertussis exsist in?

Answer 19

• virulent (Bvg+)
• avirulent (Bvg-)
  **There is an intermediate form called Bvg1 that has unique characteristsics

Question 20

BvgS

Answer 20

A tripartite histidine sensor kinase.

Question 21

What phenotypes does Bvg- express?

Answer 21

• they lack a flagella because they does need to move (happy where they are)
• adhesion expression increases as they want to stay put and adhere to the area they are in

Question 22

BvgA

Answer 22

response regulator (senses signals for activation)

Question 23

What are the in-virto and in-vivo activators of B. pertussis?

Answer 23

• In- vivo are unkown
• In-vitro are tempurature and Ca

Question 24

What is B. pertussis activation mediated by?

Answer 24

phosphorylation

Question 25

Phase variation

Answer 25

A phenotypic switch from virulent to avirulent states

Occurs at a frequency higher than spontaneous mutation (controlled/ programmed method)

Question 26

What causes phase variation in B. pertussis?

Answer 26

A frameshift mutation that inactivates BvgS that causes alpha lysis on BAP plates.