ARS | Publication request: Microarray and functional analysis of growth-phase dependent gene regulation in Bordetella bronchiseptica

Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 30, 2009
Publication Date: October 1, 2009
Citation: Nicholson, T.L., Buboltz, A.M., Harvill, E.T., Brockmeier, S.L. 2009. Microarray and Functional Analysis of Growth-Phase Dependent Gene Regulation in Bordetella bronchiseptica. Infection and Immunity. 77(10):4221-4231.

Interpretive Summary: Bordetella bronchiseptica is pervasive in swine populations and plays multiple roles in respiratory disease. Unlike the acute respiratory infections caused by B. pertussis, B. bronchiseptica infections are chronic. Growth-phase dependent gene regulation has recently been demonstrated to occur in B. pertussis, with many transcripts, including known virulence factors, significantly decreasing during the transition from logarithmic to stationary-phase growth. Given that B. pertussis is thought to have derived from a B. bronchiseptica-like ancestor, we hypothesized that growth-phase dependent gene regulation would also occur in B. bronchiseptica. Data reported here demonstrate that growth-phase dependent gene regulation occurs in B. bronchiseptica resulting in prominent shifts in global gene expression. Two virulence phenotypes associated with these gene expression changes were tested. We found that growth-dependent increases in expression of some type three secretion genes led to a growth phase-dependent increase in cytotoxicity, a type three secretion dependent function. Although the transcription of genes encoding adhesins previously shown to mediate adherence were decreased in late log and stationary phases, we found B. bronchiseptica adherence to increase in these later phases of growth. These results provide a crucial understanding of the genes and therefore antigens expressed during late or chronic infections, which will expedite the discovery of new targets for vaccine therapy to prevent these chronic infections.

Technical Abstract: Growth-phase dependent gene regulation has recently been demonstrated to occur in B. pertussis, with many transcripts, including known virulence factors, significantly decreasing during the transition from logarithmic to stationary-phase growth. Given that B. pertussis is thought to have derived from a B. bronchiseptica-like ancestor, we hypothesized that growth-phase dependent gene regulation would also occur in B. bronchiseptica. Microarray analysis revealed and qRT-PCR confirmed that growth-phase dependent gene regulation occurs in B. bronchiseptica resulting in prominent temporal shifts in global gene expression. Two virulence phenotypes associated with these gene expression changes were tested. We found that growth-dependent increases in expression of some TTSS genes led to a growth phase-dependent increase in a TTSS-dependent function, cytotoxicity. Although the transcription of genes encoding adhesins previously shown to mediate adherence were decreased in late log and stationary phases, we found B. bronchiseptica adherence to increase in these later phases of growth. Microarray analysis revealed and qRT-PCR confirmed growth-phase dependent gene regulation occurring in both Bvg+ and Bvg¬¯ phase-locked mutants, indicating that growth-phase dependent gene regulation in B. bronchiseptica can function independently from the BvgAS regulatory system.