BvrR/BvrS-Controlled Outer Membrane Proteins Omp3a and Omp3b Are Not Essential forBrucella abortusVirulence

• DOI: 10.1128/iai.00439-07
• Publication Date: 2007-07-31T00:59:11Z
• Authors: Lorea Manterola; Caterina Guzmán-...; Esteban Chaves-Ol...; Elías Barquero-C...; María-Jesús de ...; Ignacio Moriyón; María-Jesús Gri...; Ignacio López-Goñi; Edgardo Moreno
• Keywords: 0301 basic medicine; Neutrophils; Bacterial Outer membrane proteins physiology; BRUCELLA ABORTUS; Colony Count, Microbial; Brucella abortus; Virulence factors physiology; Bacterial Adhesion; Brucellosis; Cell Line; Mice; 03 medical and health sciences; Bacterial Proteins; Animals; Humans; BRUCELLA; Mice, Inbred BALB C; Virulence; Tumor Necrosis Factor-alpha; Macrophages; Brucella abortus pathogenicity; Mutagenesis, Insertional; BRUCELOSIS; VIRULENCE; VIRUS; Female; Virulence genetics; Gene Deletion; Spleen; Bacterial Outer Membrane Proteins; HeLa Cells

ABSTRACTTheBrucella abortustwo-component regulatory system BvrR/BvrS controls the expression of outer membrane proteins (Omp) Omp3a (Omp25) and Omp3b (Omp22). Disruption ofbvrSorbvrRgenerates avirulent mutants with altered cell permeability, higher sensitivity to microbicidal peptides, and complement. Consequently, the role of Omp3a and Omp3b in virulence was examined. Similar tobvrSorbvrRmutants,omp3aandomp3bmutants displayed increased attachment to cells, indicating surface alterations. However, they showed unaltered permeability; normal expression of Omp10, Omp16, Omp19, Omp2b, and Omp1; native hapten polysaccharide; and lipopolysaccharide and were resistant to complement and polymyxin B at ranges similar to those of the wild-type (WT) counterpart. Likewise,omp3aandomp3bmutants were able to replicate in murine macrophages and in HeLa cells, were resistant to the killing action of human neutrophils, and persisted in mice, like the WT strain. Murine macrophages infected with theomp3amutant generated slightly higher levels of tumor necrosis factor alpha than the WT, whereas thebvrSmutant induced lower levels of this cytokine. Since the absence of Omp3a or Omp3b does not result in attenuation, it can be concluded that BvrR/BvrS influences additionalBrucellaproperties involved in virulence. Our results are discussed in the light of previous works suggesting that disruption ofomp3agenerates attenuatedBrucellastrains, and we speculate on the role of group 3 Omps.