title: Laboratory adaptation of Bordetella pertussis is associated with the loss of type three secretion system functionality.
abstract: Although Bordetella pertussis contains and transcribes loci encoding type III secretion system (TTSS) homologues, expression of TTSS-associated proteins has been reported only for non-laboratory-adapted Irish clinical isolates. Here we confirm such a result for clinical isolates obtained from patients treated in Argentinean hospitals. Moreover, we demonstrate that the expression of TTSS-associated proteins is independent both of the year in which the isolate was obtained and of the types of polymorphic alleles for other virulence factors but is dependent on environmental growth conditions. Interestingly, we observed that TTSS-associated protein expression is lost after successive in vitro passages but becomes operative again when bacteria come into contact with the host. This in vivo activation of TTSS expression was observed not only for clinical isolates previously adapted to the laboratory after successive in vitro passages but also for vaccine strains that did not express the system in vitro. The reversibility of TTSS expression, demonstrated by its switching off-on when the bacterium comes into contact with the host, appears to be an adaptive response of this pathogen.
authors: Instituto de Biotecnología y Biología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata CONICET, Calle 47 y 115, La Plata 1900, Argentina.
authors: M E
authors: ME
authors: Gaillard
authors: D
authors: D
authors: Bottero
authors: C E
authors: CE
authors: Castuma
authors: L A
authors: LA
authors: Basile
authors: D
authors: D
authors: Hozbor
mesh_terms: D000483:Alleles; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D058947:Bacterial Secretion Systems / Q000235:genetics*; D001886:Bordetella pertussis / Q000235:genetics* / Q000472:pathogenicity*; D004777:Environment; D015964:Gene Expression Regulation, Bacterial; D054884:Host-Pathogen Interactions; D015151:Immunoblotting; D051379:Mice; D008807:Mice, Inbred BALB C; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism; D014917:Whooping Cough / Q000382:microbiology / Q000473:pathology
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D037521:Virulence Factors