This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
In which of the following organism the capsule does not act as a virulence factor? 
Select and explain. 
A. H. influenzae, B. Strept pneumoniae, C. N. meningitidis, D. Bordetella pertussis
D: Bordetella pertussis
Answer: D: Bordetella pertussis 
Explanation: Ans. is 'd' i.e., Bordetella pertussisRef: (Harrison, 19th/e, p. 1021 and Ananthanarayan, 9th/e, p. 333)Capsule of B. pertussis is not virulence factor of pertussis as Pertussis toxin (PT) - Most imp/important. Virulence factor.