Laboratory adaptation of Bordetella pertussis is associated with the loss of Type Three Secretion System functionality.

GAILLARD M.E.; BOTTERO D.; CASTUMA C.; BASILE, A.L.; HOZBOR D.

INFECTION AND IMMUNITY

AMER SOC MICROBIOLOGY

Año: 2011 p. 3677 - 3682

0019-9567

Despite the fact that Bordetella pertussis contains and transcribes the loci encoding type III secretion system (TTSS) homologues, the protein expression of TTSS was only reported for non laboratory adapted Irish clinical isolates. Here we confirm such result for the clinical isolates obtained from patients treated in Argentinean hospitals. Moreover, we demonstrate that the expression of TTSS associated proteins is independent of both the year in which the isolate was obtained and the type of polymorphic alleles described for other virulence factors, but dependent on the environmental growth condition. Interestingly, we observed that the TTSS associated protein expression is lost after successive in vitro passages but becomes again operative when bacteria come into contact with the host. This in vivo activation of TTSS expression was observed not only for the 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 turn on/off upon the bacteria coming or not in contact with the host,appears to be an adaptive response of this pathogen.