Genetics and function of the capsules of Burkholderia pseudomallei and their potential as therapeutic targets.

Burkholderia pseudomallei is the causative agent of melioidosis, a fatal disease that is endemic to Southeast Asia and northern Australia. The clinical manifestations of melioidosis may range from an acute pneumonia or acute septicemia, to chronic and latent infections. B. pseudomallei is inherently resistant to a number of antibiotics, and even with aggressive antibiotic therapy, the mortality rate remains high, and the incidence of relapse is common. The resistance of this organism to a number of antibiotics has created a need for the development of other therapeutic strategies, including the identification of novel therapeutic targets. B. pseudomallei has been shown to produce a number of capsular polysaccharides, one of which has been shown to contribute to the virulence of the organism. The structures of these polysaccharides have been determined and the genes encoding for the biosynthesis of one of the capsular polysaccharides (CPS I) have been identified. Analysis of the genome sequence of this organism has revealed the presence of three other capsule gene clusters that may encode for the chemical structures previously identified. Since one of the capsules produced by B. pseudomallei has been shown to be important in virulence, the genes encoding for the proteins responsible for its biosynthesis may be considered as potential targets.