Palacios Chaves, LeyreConde Álvarez, RaquelGil Ramírez, YolandaZúñiga Ripa, AmaiaBarquero-Calvo, ElíasChacón Díaz, CarlosChaves Olarte, EstebanArce Gorvel, VilmaGorvel, Jean-PierreMoreno, EdgardoMiguel, María Jesús deGrilló Dolset, María JesúsMoriyón Uría, IgnacioIriarte, Maite2014-06-122014-06-1220111932-6203 (electronic)59510.1371/journal.pone.0016030https://academica-e.unavarra.es/handle/2454/10827The brucellae are alpha-Proteobacteria facultative intracellular parasites that cause an important zoonosis. These bacteria escape early detection by innate immunity, an ability associated to the absence of marked pathogen-associated molecular patterns in the cell envelope lipopolysaccharide, lipoproteins and flagellin. We show here that, in contrast to the outer membrane ornithine lipids (OL) of other Gram negative bacteria, Brucella abortus OL lack a marked pathogen-associated molecular pattern activity. We identified two OL genes (olsB and olsA) and by generating the corresponding mutants found that olsB deficient B. abortus did not synthesize OL or their lyso-OL precursors. Liposomes constructed with B. abortus OL did not trigger IL-6 or TNF-alpha release by macrophages whereas those constructed with Bordetella pertussis OL and the olsB mutant lipids as carriers were highly active. The OL deficiency in the olsB mutant did not promote proinflammatory responses or generated attenuation in mice. In addition, OL deficiency did not increase sensitivity to polymyxins, normal serum or complement consumption, or alter the permeability to antibiotics and dyes. Taken together, these observations indicate that OL have become dispensable in the extant brucellae and are consistent within the trend observed in alpha-Proteobacteria animal pathogens to reduce and eventually eliminate the envelope components susceptible of recognition by innate immunity.application/pdfeng© 2011 Palacios-Chaves et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Bactericidal cationic peptidesPseudomonas fluorescensLipopolysaccharideResistanceMutantsCellsMicePhosphatidylcholineFlavobacteriumIdentificationinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess