Molecular targets for rapid identification ofBrucella spp

Abstract

Abstract

Background Brucella is an intracellular pathogen capable of infecting animals and humans. There are six recognized species ofBrucella that differ in their host preference. The genomes of the threeBrucella species have been recently sequenced. Comparison of the three revealed over 98% sequence similarity at the protein level and enabled computational identification of common and differentiating genes. We validated these computational predictions and examined the expression patterns of the putative unique and differentiating genes, using genomic and reverse transcription PCR. We then screened a set of differentiating genes against classicalBrucella biovars and showed the applicability of these regions in the design of diagnostic tests.

Results We have identified and tested set of molecular targets that are associated in unique patterns with each of the sequencedBrucella spp. A comprehensive comparison was made among the published genome sequences ofB. abortus, B. melitensis andB. suis. The comparison confirmed published differences between the threeBrucella genomes, and identified subsets of features that were predicted to be of interest in a functional comparison ofB. melitensis andB. suis toB. abortus. Differentiating sequence regions fromB. abortus, B. melitensis andB. suis were used to develop PCR primers to test for the existence andin vitro transcription of these genes in these species. OnlyB. suis is found to have a significant number of unique genes, but combinations of genes and regions that exist in only two out of three genomes and are therefore useful for diagnostics were identified and confirmed.

Conclusion Although not all of the differentiating genes identified were transcribed under steady state conditions, a group of genes sufficient to discriminate unambiguously betweenB. suis,B. melitensis, andB. abortus was identified. We present an overview of these genomic differences and the use of these features to discriminate among a number ofBrucella biovars.