The analysis of the intramacrophagic virulome of Brucella suis deciphers the environment encountered by the pathogen inside the macrophage host cell.
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."
Kohler
Stephan
S
Institut National de la Santé et de la Recherche Médicale U-431 (INSERM U-431), Université Montpellier II, France. kohler@crit.univ-montp2.fr
Foulongne
Vincent
V
Ouahrani-Bettache
Safia
S
Bourg
Gisele
G
Teyssier
Jacques
J
Ramuz
Michel
M
Liautard
Jean-Pierre
JP
D000222:Adaptation, Physiological; D000596:Amino Acids / Q000096:biosynthesis; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D041021:Brucella suis / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D050260:Carbohydrate Metabolism; D002455:Cell Division; D004579:Electron Transport; D005798:Genes, Bacterial; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D050356:Lipid Metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D008264:Macrophages / Q000382:microbiology*; D008856:Microscopy, Fluorescence; D016254:Mutagenesis, Insertional; D009584:Nitrogen / Q000378:metabolism; D009711:Nucleotides / Q000096:biosynthesis; D014617:Vacuoles / Q000382:microbiology; D014774:Virulence / Q000235:genetics
D000596:Amino Acids; D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D008164:Luminescent Proteins; D009711:Nucleotides; D049452:Green Fluorescent Proteins; D009584:Nitrogen