GIFeGSH: A New Genomic Island Might Explain the Differences in Brucella Virulence

An imported dog was confirmed to be positive with canine brucellosis in Sweden in 2010. The whole genome of Brucella canis SVA10 was subjected to phage analysis (WGS-PA) and was assigned to the Asian B. canis cluster. Further analysis indicated that the genome of B. canis SVA10 is smaller compared to genomes of the same species. A 35,781 bp genomic island (GI) was found to be absent in strain SVA10 which was detected by read mapping the paired reads to the genome of B. canis ATCC 23,365. The lacking genes of genomic island GIFeGSH are mainly coding for iron uptake enzymes and parts of the glutathione pathway. A screening of all available whole genome sequences of Brucella strains confirmed that GIFeGSH is also missing in four more strains of B. canis but present in several strains of B. abortus, B. melitensis, B. suis, B. ovis, B. microti, B. pinnipedialis, and B. ceti. Parts of the GI were present, but scattered in two other B. canis strains. The aim of this study was to find differences in the genomes of Brucella which might explain former described differences in virulence. The analysis was extended to all available Brucella genomes after the detection of a genomic island in strain SVA10.