Role of Brucella suis adhesins (BmaA and BmaB) in the initial interaction with the host cell

BIALER, M. G.; POSADAS, D. M.; RUIZ-RANWEZ, M.V.; LANGER, T; ZORREGUIETA, A

Rosario

Congreso; L Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2014

Sociedad Argentina de Bioquímica y Biología Molecular

Brucella spp. is an intracellular pathogen responsible for brucellosis, a zoonotic disease that affects livestock. Brucella survives and proliferates within several types of phagocytic and non-phagocytic cells. Adhesion of brucellae to host surfaces was proposed to be a critical step in the infection process. Brucella genomes are very similar between species; however, it seems that much of the variability is associated to surface proteins, suggesting that they could contribute to host preference and tissue tropism. Previously, we have identified by phage display a fibronectin binding protein (BmaC) of Brucella suis that belongs to the type I monomeric autotransporter (ATI).  BmaC was required for the binding of Brucella to epithelial cells.  Through phylogenetic analysis we identified in the genome of B. suis 1330 two additional members of the ATI, BmaA and BmaB, which were shown to harbor putative adhesion motifs. The aim of this work is to explore the role(s) of BmaA and BmaB in the interaction with the host as well as the presence and variability of their orthologs in different species/strains. Our results show that bmaA and bmaB are pseudogenized in some strains of B. melitensis and B. abortus. An heterologous approach revealed that they confer adhesive properties to a non-adherent non-invasive E.coli strain. Besides, mutants in the ATIs showed a significant reduction in the adherence to different model cells, strongly suggesting that they may contribute to an efficient interaction with host cells before internalization.