Abstract
BackgroundThe lipopolysaccharide is a major antigen and virulence factor of Brucella, an important bacterial pathogen. In smooth brucellae, lipopolysaccharide is made of lipid A-core oligosaccharide and N-formylperosamine O-polysaccharide. B. ovis and B. canis (rough species) lack the O-polysaccharide.ResultsThe polymorphism of O-polysaccharide genes wbkE, manAO-Ag, manBO-Ag, manCO-Ag, wbkF and wbkD) and wbo (wboA and wboB), and core genes manBcore and wa** was analyzed. Although most genes were highly conserved, species- and biovar-specific restriction patterns were found. There were no significant differences in putative N-formylperosamyl transferase genes, suggesting that Brucella A and M serotypes are not related to specific genes. In B. pinnipedialis and B. ceti (both smooth), manBO-Ag carried an IS711, confirming its dispensability for perosamine synthesis. Significant differences between smooth and rough species were found in wbkF and wbkD, two adjacent genes putatively related to bactoprenol priming for O-polysaccharide polymerization. B. ovis wbkF carried a frame-shift and B. canis had a long deletion partially encompassing both genes. In smooth brucellae, this region contains two direct repeats suggesting the deletion mechanism.ConclusionThe results define species and biovar markers, confirm the dispensability of manBO-Ag for O-polysaccharide synthesis and contribute to explain the lipopolysaccharide structure of rough and smooth Brucella species.
Highlights
The lipopolysaccharide is a major antigen and virulence factor of Brucella, an important bacterial pathogen
PCR amplification of wbkE, manBO-Ag, manAO-Ag, manCO-Ag, wkdD, wbkF, wboA and wboB, wa** and manBcore was conducted on representative strains of each of the Brucella species included in this study and their biovars with attention to the LPS characteristics (i.e. S versus R; and A dominant, M dominant, or A = M for the SLPS)
Except for wboA and wboB in B. ovis, all genes were successfully amplified in the strains of all Brucella species and biovars tested
Summary
The lipopolysaccharide is a major antigen and virulence factor of Brucella, an important bacterial pathogen. B. ovis and B. canis (rough species) lack the O-polysaccharide. B. abortus, B. melitensis, B. suis, B. neotomae, B. ovis, and B. canis have been known for a long (page number not for citation purposes). Some Brucella strains have been isolated from the common vole and a new species, B. microti, proposed [4]. B. abortus, B. melitensis and B. suis have been classically subdivided into biovars according to H2S production, CO2-dependence, dye sensitivity and distribution of the A and M epitopes (see below) [2]. Because these tests are difficult to standardize, molecular markers have been investigated [5,6,7,8,9]
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