The filamentous hemagglutinin of Bordetella parapertussis is the major adhesin in the phase-dependent interaction with NCI-H292 human lung epithelial cells.

Bordetella parapertussis is a Gram-negative bacterium which colonizes the human respiratory tract and can cause whooping cough or pertussis. This pathogen is subject to phase variation and expresses a series of virulence factors exclusively in the Bvg+ phase. Here, it is demonstrated for the first time that only the Bvg+ phase of B. parapertussis adheres to and invades the human lung epithelial cell line NCI-H292. A B. parapertussis mutant defective in expression of the Bvg+-regulated filamentous hemagglutinin (FHA) showed reduced binding (77% reduction) to NCI-H292 cells, as did a FHA mutant of the related Bordetella pertussis (85% reduction). In contrast to B. pertussis, binding of B. parapertussis to NCI-H292 cells was not inhibited by heparin, suggesting differences in the FHA adhesin and its host-cell receptor between these two species. Thorough understanding of the mechanism of action of the B. parapertussis virulence factors, such as FHA, is of particular interest in the development of novel strategies of pertussis vaccination.