In silico, the four genomes available showed low polymorphism. A single nucleotide deletion at position 812 was detected in B. ovis, which should modify the C-terminal sequence of the protein (Figure 5). Similarly, a low degree of polymorphism was observed in wa **. With the exception of B. suis biovar 2, one Pst I pattern was specific of B. suis. Biovar 2 also lacked an Ava II site, which could be considered as a biovar marker. With Hinf 1, a pattern was specific of B. ovis (Figure 2, Table 1). Discussion Despite the high DNA homology of brucellae, gene polymorphism and species- and biovar-specific markers have been consistently found. Concerning outer

membrane molecules, both have been found in genes of proteins [16,18,19] but not in the LPS genes examined, all of the wbk region ( wbkA, gmd, per, wzm, wzt, wbkB, and wbkC ). Interestingly, these O-polysaccharide genes were found to be highly conserved not only in the classical GSK690693 molecular weight S Brucella species and Tozasertib biovars but also in B. ovis and B. canis, the two species that lack the O-polysaccharide [14]. Therefore, an implication of these observations is that the R click here phenotype of B. ovis and B. canis cannot be explained by the absence of any of those seven wbk genes. More recently, the wbk region has been extended to include wbkE, manA O -

Ag , manB O – Ag , manC O – Ag , wbkF, and wkdD [12]. The present study includes an analysis of some of these genes and the results not only show the existence of specific markers but, more important, they also improve our understanding of the genetics-structure relationship in Brucella LPS. Concerning the O-polysaccharide, the results are relevant to interpret the variations in O-polysaccharide linkages of S Brucella and add further weight to our previous finding (12) that the putative mannose genes in wbk are not essential for perosamine synthesis.

Furthermore, they help to explain the differences existing between S and R Brucella species. Despite extensive transposon mutagenesis searches, only four putative glycosyltransferase genes have been implicated in N-formylperosamine polymerization in Brucella : wbkA, wbkE, wboA and wboB. As mentioned above, wbkA is conserved in classical Brucella species [14], and the Farnesyltransferase results reported here show that wboA, wboB and wbkE are similarly present in S B. melitensis, B. abortus, B. suis, B. pinnipedialis and B. ceti. Moreover, these genes displayed low polymorphism, no matter the A or M serotype. It has to be noted that the consensus sequences of glycosyltransferases are conspicuous enough to make unlikely the existence of O-polysaccharide transferases other than wboA, wboB, wbkA and wbkE, and that, although the α (1–3) linkage relates to the M serotype, there is evidence showing that at least some A dominant strains generate a very small proportion (i.e. 2%) of α (1–3) linkages [20].