Pan-core proteome analysis of pathogenic Brucella spp. with worldwide geographic distribution. A A total 213 strains of B. abortus, B. melitensis, and B. suis with clear genetic isolation information were selected in pan-core proteome analysis. B Representative strains covering major brucellosis-epidemic areas such as Asia, Europe and the Americas. C A genome-based neighbour-joining phylogenetic tree was constructed based on concatenated core protein alignments. The core/accessory/unique proteome was defined as coverage > 95%, 95–15%, and < 15%, respectively.