Involvement of operon phaABCDEFG in virulence and intracellular multiplication of Brucella abortus

M. ROSET, A. E. CIOCCHINI, N. IÑÓN DE IANNINO Y R. A. UGALDE.

Villa Carlos Paz, Cordoba, Argentina

Congreso; XXXVII Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB 2001); 2001

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB)

Brucella abortus is an intracellular pathogen that invades and multiplies in eukaryotic cells without producing signs of toxicity or induce apoptosis. Brucella spp. causes chronic infection in several species of mammals including humans. These bacteria have developed strategies for intracellular lifestyle to avoid the immune responses. This characteristic resembles the behavior of endosymbionts. Molecular virulence mechanisms of Brucella spp. are not yet fully understood. Identification of genes involved in these processes will allow a better understanding of pathogenesis and virulence. A Bruella abortus 2308 genome project carried out in our institute let us the identification of a number of open reading frames highly similar to Rhizobium nodulation and Agrobacterium virulence genes. The operon phaABCDEFG in Sinorhizobium meliloti code for a K + secretion system that is involved in the adaptation to pH changes and in symbiosis. In B. abortus the complete phaABCDEFG operon was identified. A B. abortus 2308 phaA polar mutant displayed a defective intracellular multiplication in HeLa cells. However in murine macrophage-like J774 cells the intracellular multiplication of the mutant was similar to that of the wild type strain. These results suggest that the B. abortus phaABCDEFG operon might be important for adaptation to the intracellular lifestyle and virulence.