Identification of a pathogenicity island of Brucella abortus involved in the invasion of host cells

CECILIA CZIBENER; MARIELA DEL GIUDICE; EZEQUIEL VALGUARNERA; JUAN UGALDE

Tucuman, Argentina

Congreso; SAIB 45th Annual Meeting; 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Brucella abortus is a facultative intracellular pathogen that belongs to the alpha proteobacteria group and causes brucellosis, a worldwide zoonosis important for animal breading and of human health impact in endemic areas. The virulence of Brucella is dependent on the capacity of the bacteria to invade, persist and replicate within host cells, a task that depends on the presence of specialized virulence factors. With the aim of finding and characterizing novel virulence factors, we used a bioinformatic approach to search for potential proteins that might play a role in the intracellular survival. Our search identified a pathogenicity island that harbours four open reading frames, one of which (Bab1_2009) has a domain with homology to the intimin of E. coli EPEC, a receptor essential for attachment of this pathogen to the host cell. The other three ORFs are unique to Brucella and have no significant homology to any proteins in the database. Deletion of the entire island resulted in 10 times less invasion than the wild type parental strain measured by a standard antibiotic protection assay. Moreover, over-expression of Bab1_2009 in the wild type strain rendered a strain that is at least 100 times more efficient in invading either phagocytic as well as non-phagocytic cells. Our results indicate that this novel pathogenicity island is involved in the invasion process of host cells.