A novel B. suis Adhesin identified by Phage Display mediates Bacterial Adhesion to Epithelial cells

POSADAS DM, RUÍZ V, BONOMI HR, MARTÍN FA, ZORREGUIETA A

Puerto Madryin

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Brucella is an intracellular pathogen responsible for the zoonotic disease called brucellosis. Adhesins are important virulence factors in bacterial infections. However,little is known about these molecules in brucellaceae. In an attempt to identify genes coding for adhesins to some key components of the host extracellular matrix molecules, a phage display library of fragmented genomic DNA from B. suis was prepared in pG8SAET vector. Three genes encoding putative Fibronectin-binding molecules were identified by using panning procedures. Binding specificity to fibronectin was confirmed by ELISA and panning experiments for all candidates. One of these candidates, designated BmaC, belongs to the type I autotransporter protein family. Phages displaying fusions to BmaC peptides were able to adhere to culture cells and blocked the binding of B. suis to HeLa cells in a dose-dependent manner. A deletion mutant in the bmaC gene was obtained, and adhesion capability in this strain was determined.  In co-infection experiments of epithelial cells the wild type strain out-competed a  bmaC-deletion mutant showing that bmaC contributes to adherence to model cells. Biochemical and microscopy studies suggest that BmaC is a surface-exposed adhesin, localized in the outer membrane of the bacteria.  BmaC may have a crucial role in the interaction of B. suis with its host.