Abstract
The past decade has seen an explosion of genomic sequencing for Brucella, with over 1,110 genomes now available. However, the large majority of these genomes come from just two species, Brucella abortus and B. melitensis, which is no coincidence due to the ubiquity of these two Brucella and their pervasive impacts on livestock, wildlife, and humans worldwide. Phylogenomics can be used on contemporary isolates, as well as from ancient DNA from fossils, to understand the timing of spread and their evolution. The primary finding is that the current distribution of B. abortus and B. melitensis is intimately tied to human movement of livestock across the globe-as livestock get moved so too do their pathogens. Both B. abortus and B. melitensis have striking similarities to each other, linked to human colonization patterns but also have key, but unexplained differences. Brucella abortus has one successful lineage that is found throughout the world, but also contains considerable diversity of numerous and divergent lineages, especially in Africa and Asia. Brucella melitensis in contrast has three successful lineages but relatively little diversity outside of these three groups. This talk will compare and contrast Brucella genomes to help explain how human movement has shaped these two important Brucella species over the past few thousand years and continuing to today.
