MOLECULAR CHARACTERIZATION OF VIRULENCE FACTORS IN Brucella abortus

DOHMER, PETER H.; CZIBENER C; UGALDE JE

Mendoza

Congreso; XLVIII Reunión Anual SAIB; 2012

Argentine Society for Biochemistry and Molecular Biology Research

Virulence of Brucella depends on the capacity to survive within the host cells. To achieve this the bacterium has evolved strategies to escape recognition by the immune system. Although much has been done on the mechanisms that allow the bacterium to survive within the host cell, few virulence factors have been identified to date. The aim of this work was to study and characterize a new virulence factor involved in the intracellular survival. Using a bioinformatic approach we searched the Brucella genome for genomic regions with potential horizontally transmitted characteristics with the premise that they might contain novel virulence factors. With this approach we identified several gene candidates that were flagtagged to determine protein localization during infection. One of them, Bab1_1492, is secreted from the bacteria and, most probably, localizes to the Brucella containing vacuole. A deletion mutant in this gene showed a significant defect in the intracellular replication rate during the first hours of infection in professional and nonprofessional phagocytic cells. To further characterize this gene we evaluated the internalization process and the intracellular trafficking and showed that although the mutant strain has greater internalization, it has an increased degradation rate, consistent with the altered intracellular replication kinetic.