Response of murine splenocytes to infection with wild type or virB mutant Brucella strains

The virB operon, encoding a Type IV secretion system (T4SS), is essential for intracellular survival and persistent infection of Brucella spp. To better understand the role of the T4SS in evading host defense mechanisms and establishing chronic infection, we compared transcriptional profiles of the host response to infection with wild type Brucella strains and strains that fail to express the virB genes. Analysis of host gene expression profiles three days after inoculation with wild type Brucella strains revealed an inflammatory response dominated by interferon-induced genes. This analysis found that not only the type II but also type I interferon pathway was elicited by Brucella infection. Real time RT-PCR showed that a group of genes from these pathways was induced by day 3 post-infection and declined to baseline levels by day 7. In contrast, neither of the two virB mutant strains elicited expression of interferon-induced genes, demonstrating that the T4SS was required to trigger an inflammatory response early during infection.

10

Roux CM, Rolán HG, Santos RL, Beremand PD, Thomas TL, Adams LG, Tsolis RM