In vivo colonization profile study of Bordetella bronchiseptica in the nasal cavity.

Bordetella bronchiseptica chronically infects a wide range of mammals, and resides primarily in the nasal cavity of the infected host. Multiple virulence factors of Bordetella species have been studied in the context of lower respiratory tract infections, but relatively less is known about the bacterial life cycle in the nasal cavity. Evidences were discovered for Bvg intermediate (Bvg(i)) phase expression in vivo and that the major adhesin filamentous hemagglutinin plays a major role in the colonization of B.

Bordetella bronchiseptica modulates macrophage phenotype leading to the inhibition of CD4+ T cell proliferation and the initiation of a Th17 immune response.

Bordetella bronchiseptica is a Gram-negative bacterium equipped with several colonization factors that allow it to establish a persistent infection of the murine respiratory tract. Previous studies indicate that B. bronchiseptica adenylate cyclase toxin (ACT) and the type III secretion system (TTSS) synergize to drive dendritic cells into an altered phenotype to down-regulate the host immune response.

Expression of the primary carbohydrate component of the Bordetella bronchiseptica biofilm matrix is dependent on growth phase but independent of Bvg regulation.

We previously showed that the Bvg virulence control system regulates biofilm formation in Bordetella bronchiseptica (Y. Irie, S. Mattoo, and M.

Bordetella type III secretion modulates dendritic cell migration resulting in immunosuppression and bacterial persistence.

Chronic bacterial infection reflects a balance between the host immune response and bacterial factors that promote colonization and immune evasion. Bordetella bronchiseptica uses a type III secretion system (TTSS) to persist in the lower respiratory tract of mice. We hypothesize that colonization is facilitated by bacteria-driven modulation of dendritic cells (DCs), which leads to an immunosuppressive adaptive host response.

A genome-wide screen identifies a Bordetella type III secretion effector and candidate effectors in other species.

Bordetella bronchiseptica utilizes a type III secretion system (TTSS) for induction of non-apoptotic cytotoxicity in host cells and modulation of host immunity. The identity of Bordetella TTSS effectors, however, has remained elusive. Here we report a genome-wide screen for TTSS effectors based on shared biophysical and functional characteristics of class I chaperones and their frequent colocalization with TTSS effectors.

Pseudomonas aeruginosa rhamnolipids disperse Bordetella bronchiseptica biofilms.

We have previously reported that the respiratory pathogen Bordetella bronchiseptica can form biofilms in vitro. In this report, we demonstrate the disruption of B. bronchiseptica biofilms by rhamnolipids secreted from Pseudomonas aeruginosa.

Suppression of NF-kappaB-mediated beta-defensin gene expression in the mammalian airway by the Bordetella type III secretion system.

Expression of innate immune genes such as beta-defensins is induced in airway epithelium by bacterial components via activation of NF-kappaB. We show here that live Gram-negative bacteria can similarly stimulate this pathway, resulting in upregulation of the beta-defensin tracheal antimicrobial peptide (TAP) in primary cultures of bovine tracheal epithelial cells (TECs), by a Toll-like receptor 4 (TLR4)-mediated pathway. The Gram-negative airway pathogen Bordetella bronchiseptica possesses a type III secretion system previously suggested to inhibit the nuclear translocation of NF-kappaB in a cell line by immunohistochemistry.

Downregulation of mitogen-activated protein kinases by the Bordetella bronchiseptica Type III secretion system leads to attenuated nonclassical macrophage activation.

Bordetella bronchiseptica utilizes a type III secretion system (TTSS) to establish a persistent infection of the murine respiratory tract. Previous studies have shown that the Bordetella TTSS mediated cytotoxicity in different cell types, inhibition of NF-kappaB in epithelial cells, and differentiation of dendritic cells into a semimature state. Here we demonstrate modulation of mitogen-activated protein kinase (MAPK) signaling pathways and altered cytokine production in macrophages and dendritic cells by the Bordetella TTSS.

The Bvg virulence control system regulates biofilm formation in Bordetella bronchiseptica.

Bordetella species utilize the BvgAS (Bordetella virulence gene) two-component signal transduction system to sense the environment and regulate gene expression among at least three phases: a virulent Bvg+ phase, a nonvirulent Bvg- phase, and an intermediate Bvgi phase. Genes expressed in the Bvg+ phase encode known virulence factors, including adhesins such as filamentous hemagglutinin (FHA) and fimbriae, as well as toxins such as the bifunctional adenylate cyclase/hemolysin (ACY). Previous studies showed that in the Bvgi phase, FHA and fimbriae continue to be expressed, but ACY expression is significantly downregulated.

Bordetella type III secretion and adenylate cyclase toxin synergize to drive dendritic cells into a semimature state.

Bordetella bronchiseptica establishes persistent infection of the murine respiratory tract. We hypothesize that long-term colonization is mediated in part by bacteria-driven modulation of dendritic cells (DCs) leading to altered adaptive immune responses. Bone marrow-derived DCs (BMDCs) from C57BL/6 mice infected with live B.

Regulation of type III secretion in Bordetella.

The BvgAS virulence control system regulates the expression of type III secretion genes in Bordetella subspecies that infect humans and other mammals. We have identified five open reading frames, btrS, btrU, btrX, btrW and btrV, that are activated by BvgAS and encode regulatory factors that control type III secretion at the levels of transcription, protein expression and secretion. The btrS gene product bears sequence similarity to ECF (extracytoplasmic function) sigma factors and is required for transcription of the bsc locus.

Comparative phenotypic analysis of the Bordetella parapertussis isolate chosen for genomic sequencing.

The genomes of three closely related bordetellae are currently being sequenced, thus providing an opportunity for comparative genomic approaches driven by an understanding of the comparative biology of these three bacteria. Although the other strains being sequenced are well studied, the strain of Bordetella parapertussis chosen for sequencing is a recent human clinical isolate (strain 12822) that has yet to be characterized in detail. This investigation reports the first phenotypic characterization of this strain, which will likely become the prototype for this species in comparison with the prototype strains of B.