Adhesion, invasion and intracellular replication of Brucella in polarized ephitelial cells

CZIBENER C; MERWAISS F; UGALDE JE

Berlin

Congreso; Brucellosis 2014 International Research Conference; 2014

Friedrich- Loeffler- Institut

Virulence in Brucella is completely dependent on the capacity of the bacteria to invade, survive and replicate in the host cells, particularly in professional phagocytes such as macrophages and dendritic cells. Because of this, much has been done in order to understand the intracellular life cycle of the bacteria in these cell types and a good body of information has been generated regarding invasion and trafficking. Albeit this little is known about the intracellular behavior of Brucella in polarized epithelial cells, the first cell type encountered by the bacteria upon infection of the host. We present here the identification of an adhesin (ilgA), conserved in all Brucella species that harbors an intimin-like domain and mediates the adhesion and invasion of Madin-Darby canine kidney (MDCK) cells and other epithelial cells. Our results indicate that Brucella is able to invade and replicate in MDCK cells and that invasion occurs through the cell-cell interaction membrane in a process that depends, in part, on ilgA. IlgA knock out significantly decreased adhesion to host cells and overexpression of the gene dramatically increased both adhesion and invasion, indicating that this gene plays a central role in the initial interaction with the cells. Treatment of different cell lines with the recombinant intimin-like domain of IlgA showed that it localized to focal adhesion sites and induced complete detachment of the cells suggesting that it targets proteins in these structures. Additionally, we have performed a detailed microscopic analysis of the intracellular life cycle in these cells and show that the bacteria achieve a complete cycle including a programmed exiting to re-infect other cells.