Bordetella pertussis expresses a functional type III secretion system that

FENNELLY N; SISTI FEDERICO; HIGGINS SC; ROSS PJ; VAN DER HEIDE H; MOOI F; BOYD A; MILLS KH

INFECTION AND IMMUNITY

Año: 2008 p. 1257 - 1266

0019-9567

Certain bacteria use a type III secretion system (TTSS) to deliver effectorproteins that interfere with cell function into host cells. While transcriptionof genes encoding TTSS components has been demonstrated, studies to date havefailed to identify TTSS effector proteins in Bordetella pertussis. Here wepresent the first evidence of a functionally active TTSS in B. pertussis. Threeknown TTSS effectors, Bsp22, BopN, and BopD, were identified as TTSS substratesin B. pertussis 12743. We found expression of Bsp22 in a significant proportionof clinical isolates but not in common laboratory-adapted strains of B.pertussis. We generated a TTSS mutant of B. pertussis 12743 and showed that itinduced significantly lower respiratory tract colonization in mice than thewild-type bacteria. Respiratory infection of mice with the mutant bacteriainduced significantly greater innate proinflammatory cytokine production in thelungs soon after challenge, and this correlated with significantly higherantigen-specific interleukin-17, gamma interferon, and immunoglobulin G responseslater in infection. Our findings suggest that the TTSS subverts innate andadaptive immune responses during infection of the lungs and may be a functionallyimportant virulence factor for B. pertussis infection of humans.