The Analysis of the Intramacrophagic Virulome of Brucella suis Deciphers the Environment Encountered by the Pathogen inside the Macrophage Host Cell

• Published in: Proceedings of the National Academy of Sciences - PNAS 2002-11, Vol.99 (24), p.15711-15716
• Main Authors: Köhler, Stephan, Foulongne, Vincent, Ouahrani-Bettache, Safia, Bourg, Gisèle, Teyssier, Jacques, Ramuz, Michel, Liautard, Jean-Pierre
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Amino acids; Amino Acids - biosynthesis; Anaerobiosis; Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Biological Sciences; Brucella; Brucella suis - genetics; Brucella suis - pathogenicity; Brucella suis - physiology; Carbohydrate Metabolism; Cell Division; Cells; Electron Transport; Genes; Genes, Bacterial; Genes, Reporter; Genomes; Green Fluorescent Proteins; Infections; Lipid Metabolism; Lipopolysaccharides - metabolism; Luminescent Proteins - analysis; Luminescent Proteins - genetics; Macrophages; Macrophages - microbiology; Microbiology; Microscopy, Fluorescence; Mutagenesis, Insertional; Nitrates; Nitrogen - metabolism; Nucleotides - biosynthesis; Pathogens; Phagosomes; Transcriptional regulatory elements; Vacuoles - microbiology; Virulence; Virulence - genetics
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.232454299

The pathogen Brucella suis resides and multiplies within a phagocytic vacuole of its host cell, the macrophage. The resulting complex relationship has been investigated by the analysis of the set of genes required for virulence, which we call intramacrophagic virulome. Ten thousand two hundred and seventy-two miniTn5 mutants of B. suis constitutively expressing gfp were screened by fluorescence microscopy for lack of intracellular multiplication in human macrophages. One hundred thirty-one such mutants affected in 59 different genes could be isolated, and a function was ascribed to 53 of them. We identified genes involved in (i) global adaptation to the intracellular environment, (ii) amino acid, and (iii) nucleotide synthesis, (iv) sugar metabolism, (v) oxidoreduction, (vi) nitrogen metabolism, (vii) regulation, (viii) disulphide bond formation, and (ix) lipopolysaccharide biosynthesis. Results led to the conclusion that the replicative compartment of B. suis is poor in nutrients and characterized by low oxygen tension, and that nitrate may be used for anaerobic respiration. Intramacrophagic virulome analysis hence allowed the description of the nature of the replicative vacuole of the pathogen in the macrophage and extended our understanding of the niche in which B. suis resides. We propose calling this specific compartment "brucellosome."