The columns content is as indicated in Figure 3 legend. The corresponding genotyping data can be found in the additional file [see Additional file 1]. The third part of the clustering (genotypes 140 to 204) is displayed, comprising the rest of B. abortus isolates, and the B. melitensis isolates. The RB51 vaccine strain tested here is genotype 159, S19 is genotype 161, and a number of Rev1 isolates share genotype 201. The colour code used is as shown in Figure 1.