Project description:An important, but rarely performed, test of Koch’s molecular postulates involves evaluating the capacity of candidate virulence genes to confer pathogenicity in otherwise non-virulent species. Unbiased genomic surveys of avirulent natural isolates might reveal rare variants possessing specific virulence features, which might prove useful in testing their functional sufficiency. Using a custom pan-genome array, we analyzed a panel of avirulent Burkholderia thailandensis (Bt) isolates related to Burkholderia pseudomallei (Bp), the causative agent of the often fatal human and animal disease melioidosis. We report the discovery of variant Bt isolates exhibiting isolated acquisition of a capsular polysaccharide biosynthesis gene cluster (BpCPS), long regarded as an critical species-specific virulence factor essential for Bp mammalian virulence. BpCPS-expressing Bt strains exhibited certain pathogen-related phenotypes including resistance to human complement binding, but did not exhibit enhanced virulence when assessed in two different in vivo animal infection models. Phylogenetic analysis revealed that the BpCPS-expressing Bt strains likely reside within an evolutionary subgroup distinct from the majority of previously-described Bt strains. Our findings suggest that BpCPS acquisition alone is unlikely to fully explain the ability of Bp to colonize humans and animals, highlighting the importance of other collaborating factors in the pathogenesis of mammalian melioidosis.
Project description:Gene expression profiles of human cell (THP-1) lines exposed to a novel Daboiatoxin (DbTx) isolated from Daboia russelli russelli, and specific cytokines and inflammatory pathways involved in acute infection caused by Burkholderia pseudomallei. Keywords: Melioidosis, Burkholderia pseudomallei, Daboiatoxin, Cytokines, Inflammation.
Project description:An important, but rarely performed, test of Koch’s molecular postulates involves evaluating the capacity of candidate virulence genes to confer pathogenicity in otherwise non-virulent species. Unbiased genomic surveys of avirulent natural isolates might reveal rare variants possessing specific virulence features, which might prove useful in testing their functional sufficiency. Using a custom pan-genome array, we analyzed a panel of avirulent Burkholderia thailandensis (Bt) isolates related to Burkholderia pseudomallei (Bp), the causative agent of the often fatal human and animal disease melioidosis. We report the discovery of variant Bt isolates exhibiting isolated acquisition of a capsular polysaccharide biosynthesis gene cluster (BpCPS), long regarded as an critical species-specific virulence factor essential for Bp mammalian virulence. BpCPS-expressing Bt strains exhibited certain pathogen-related phenotypes including resistance to human complement binding, but did not exhibit enhanced virulence when assessed in two different in vivo animal infection models. Phylogenetic analysis revealed that the BpCPS-expressing Bt strains likely reside within an evolutionary subgroup distinct from the majority of previously-described Bt strains. Our findings suggest that BpCPS acquisition alone is unlikely to fully explain the ability of Bp to colonize humans and animals, highlighting the importance of other collaborating factors in the pathogenesis of mammalian melioidosis. Genomic DNA of several Bt strains were hybridized against a common reference strain (Bt E264), to see gain/loss
Project description:Genomic and transcriptomic analysis of trimethoprim-sulfamethoxazole and meropenem resistance in Burkholderia pseudomallei clinical isolates
Project description:Burkholderia pseudomallei is the causative agent of melioidosis a disease endemic in South-East Asia and Northern Australia. The mortality rates in these areas are unacceptably high even with antibiotic treatment, attributed to intrinsic and acquired resistance of B. pseudomallei to antibiotics. With very few options for therapeutics there is an urgent requirement to identify anti-bacterial targets for the development of novel, effective treatments. In this study we examine the role and effect of ppiB on the proteome. Using LFQ analysis we show loss of ppiB has dramatic effect on the Burkholderia pseudomallei proteome.
Project description:Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is a disease endemic to South-East Asia and Northern Australia. Clinical presentation is highly variable, ranging from asymptomatic to fatal septicaemia, and thus the outcome of infection can depend on the host immune responses. The aim of this study was to characterise the macrophage immune response to B. pseudomallei in the presence of novel inhibitors targeting the virulence factor, Macrophage Infectivity Potentiator (Mip) protein. To do this. murine macrophage J774A.1 cells were infected with B. pseudomallei K96243 in the presence and absence of two small-molecule inhibitors designed to target the Mip protein. Global transcriptional profiling of macrophages infected with B. pseudomallei was analysed by RNA-Seq four hours post-infection. In the presence of Mip inhibitors, we found a significant reduction in the expression of pro-inflammatory cytokines highlighting the potential to utilize Mip inhibitors to dampen potentially harmful pro-inflammatory responses resulting from B. pseudomallei infection in macrophages. We then performed gene expression profiling analysis using data obtained from RNA-seq of J774A.1 macrophages infected with Burkholderia pseudomallei in the presence of two Mip inhibitors or vehicle control 4 hours post-infection
Project description:Melioidosis is a neglected tropical disease caused by the Gram-negative bacterium Burkholderia pseudomallei. It is widespread in Southeast Asia and under-reported across tropical regions worldwide. Patients present with a range of clinical syndromes including sepsis, pneumonia and focal abscesses, with a mortality rate of 40% in hospitalized patients in Thailand. Up to two-thirds of patients with melioidosis have diabetes mellitus. In this experiment we sought to characterize pathways activated by whole killed B. pseudomallei bacteria and by three vaccine candidate proteins from B. pseudomallei, BPSL2520 (uncharacterized protein), BPSS1525 (BopE) and BPSL2096 (AhpC) in patients with diabetes and acute melioidosis.
Project description:We report the application of single-molecule-based sequencing technology for high-throughput profiling of DNA methylations in Burkholderia pseudomallei. SMRTbell™ sequencing
Project description:Array-CGH analysis and Burkholderia pseudomallei isolates pre and post ceftazidime relapse. Genomic DNA from both the parental strains and variant strains were labeled with Cy3 or Cy5 fluorescent dyes and hybridized onto a customized microarray with probes designed from the reference Bp K96243 genome. Log2 signal ratios of parental strain over the variant strains were then computed after normalization to find genomic loss or gain in the variant strains.