Question 1

Which of the following best explains why Bordetella pertussis remains endemic despite widespread vaccination?

Accepted Answer

Adults and adolescents often serve as asymptomatic reservoirs, sustaining transmission to infants.

Question 2

Which stage of pertussis is most infectious and characterized by sudden recurrence or intensification of short, frequent coughs?

Accepted Answer

Paroxysmal stage

Question 3

What is the primary function of filamentous hemagglutinin (FHA) in Bordetella pertussis pathogenesis?

Accepted Answer

It mediates attachment to ciliated epithelial cells via carbohydrate receptors and modulates immune responses.

Question 4

Which Bordetella species is most likely to switch between Bvg+ and Bvg- phases, allowing survival outside the host?

Accepted Answer

Bordetella bronchiseptica

Question 5

Why do current acellular pertussis vaccines have limitations in preventing outbreaks?

Accepted Answer

Waning immunity after acellular vaccination contributes to recurrent outbreaks.

Question 6

Which toxin produced by B. pertussis impairs mucociliary clearance and leads to paroxysmal cough?

Accepted Answer

Tracheal cytotoxin (TCT)

Question 7

What is the role of pertactin (Prn) in B. pertussis infection?

Accepted Answer

It contributes to stable adhesion and may assist invasion of epithelial cells, acting synergistically with FHA and fimbriae.

Question 8

Which diagnostic method is most sensitive during the first 2 weeks of pertussis symptoms?

Accepted Answer

PCR (IS481)

Question 9

How does B. pertussis evade early immune detection in the airway?

Accepted Answer

By producing LPS with reduced TLR4 activation, leading to a weaker innate response.

Question 10

Which of the following is TRUE regarding the role of OtbAB (BP1251/1252) in B. pertussis?

Accepted Answer

BP1251/1252 are novel adhesins critical for initial adhesion to respiratory tissue and are immunogenic.

Question 11

A patient presents with a persistent cough lasting over 4 weeks, cyanosis, and vomiting after coughing fits. Which stage of pertussis is most likely?

Accepted Answer

Paroxysmal stage

Question 12

Which equation best represents the relationship between the number of BvgA-binding sites and the level of gene expression in B. pertussis?

Accepted Answer

$$E = k 	imes n_{BvgA}$$

Question 13

Which of the following best describes the effect of adenylate cyclase toxin (ACT) in B. pertussis infection?

Accepted Answer

It enters phagocytes and raises cAMP, inhibiting phagocytosis and dampening inflammation.

Question 14

Why are Prn-specific antibodies important in the immune response to B. pertussis?

Accepted Answer

They enhance phagocytosis by neutrophils and macrophages through opsonisation.

Question 15

Which of the following is a major challenge associated with current acellular pertussis vaccines?

Accepted Answer

They target a limited set of antigens, allowing vaccine-driven selection of Prn-deficient strains.

Question 16

Which real-world scenario best illustrates the importance of maternal vaccination in pertussis control?

Accepted Answer

A country with high maternal vaccination rates sees a decrease in infant pertussis deaths.

Question 17

Which of the following statements about Bordetella holmesii is correct?

Accepted Answer

It shares many genomic features with B. pertussis but is a distinct species and often causes pertussis-like illness.

Question 18

Which host cell structure is targeted by B. pertussis adhesins to establish infection?

Accepted Answer

Ciliated epithelial cells

Question 19

What is the main reason for the resurgence of pertussis in countries with high vaccine coverage?

Accepted Answer

Waning immunity after acellular vaccination and asymptomatic transmission by adults.

Study Notes on Bordetella and Pertussis: Biology, Pathogenesis, and Control

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