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Bangi, Malaysia

Chin C.-Y.,National University of Malaysia | Monack D.M.,Stanford University | Nathan S.,National University of Malaysia | Nathan S.,Malaysia Genome Institute
Immunology | Year: 2012

Diabetes mellitus is a predisposing factor of melioidosis, contributing to higher mortality rates in diabetics infected with Burkholderia pseudomallei. To investigate how diabetes alters the inflammatory response, we established a streptozotocin (STZ) -induced diabetic murine acute-phase melioidosis model. Viable B. pseudomallei cells were consistently detected in the blood, liver and spleen during the 42-hr course of infection but the hyperglycaemic environment did not increase the bacterial burden. However, after 24hr, granulocyte counts increased in response to infection, whereas blood glucose concentrations decreased over the course of infection. A genome-wide expression analysis of the STZ-diabetic murine acute melioidosis liver identified ∼1000 genes whose expression was altered in the STZ-diabetic mice. The STZ-diabetic host transcriptional response was compared with the normoglycaemic host transcriptional response recently reported by our group. The microarray data suggest that the presence of elevated glucose levels impairs the host innate immune system by delaying the identification and recognition of B. pseudomallei surface structures. Consequently, the host is unable to activate the appropriate innate immune response over time, which may explain the increased susceptibility to melioidosis in the STZ-diabetic host. Nevertheless, a general 'alarm signal' of infection as well as defence programmes are still triggered by the STZ-diabetic host, although only 24hr after infection. In summary, this study demonstrates that in the face of a B. pseudomallei acute infection, poor glycaemic control impaired innate responses during the early stages of B. pseudomallei infection, contributing to the increased susceptibility of STZ-induced diabetics to this fatal disease. © 2011 The Authors. Immunology © 2011 Blackwell Publishing Ltd. Source


Low K.O.,University of Technology Malaysia | Mahadi N.M.,Malaysia Genome Institute | Illias R.Md.,University of Technology Malaysia
Applied Microbiology and Biotechnology | Year: 2013

Escherichia coli - the powerhouse for recombinant protein production - is rapidly gaining status as a reliable and efficient host for secretory expression. An improved understanding of protein translocation processes and its mechanisms has inspired and accelerated the development of new tools and applications in this field and, in particular, a more efficient secretion signal. Several important characteristics and requirements are summarised for the design of a more efficient signal peptide for the production of recombinant proteins in E. coli. General approaches and strategies to optimise the signal peptide, including the selection and modification of the signal peptide components, are included. Several challenges in the secretory production of recombinant proteins are discussed, and research approaches designed to meet these challenges are proposed. © Springer-Verlag 2013. Source


Alkotaini B.,National University of Malaysia | Anuar N.,National University of Malaysia | Kadhum A.A.H.,National University of Malaysia | Sani A.A.A.,Malaysia Genome Institute
Journal of Industrial Microbiology and Biotechnology | Year: 2013

An antimicrobial substance produced by the Paenibacillus alvei strain AN5 was detected in fermentation broth. Subsequently, cell-free culture supernatant (CFCS) was obtained by medium centrifugation and filtration, and its antimicrobial activity was tested. This showed a broad inhibitory spectrum against both Gram-positive and -negative bacterial strains. The CFCS was then purified and subjected to SDS-PAGE and infrared spectroscopy, which indicated the proteinaceous nature of the antimicrobial compound. Some de novo sequencing using an automatic Q-TOF premier system determined the amino acid sequence of the purified antimicrobial peptide as Y-S-K-S-L-P-L-S-V-L-N-P (1,316 Da). The novel peptide was designated as peptide AN5-1. Its mode of action was bactericidal, inducing cell lysis in E. coli ATCC 29522 and S. aureus, and non-cell lysis in both S. marcescens and B. cereus ATCC 14579. Peptide AN5-1 displayed stability at a wide range of pH values (2-12) and remained active after exposure to high temperatures (100 C). It also maintained its antimicrobial activity after incubation with chemicals such as SDS, urea and EDTA. © 2013 The Author(s). Source


Chin C.,National University of Malaysia | Monack D.M.,Stanford University | Nathan S.,National University of Malaysia | Nathan S.,Malaysia Genome Institute
BMC Genomics | Year: 2010

Background: At present, very little is known about how Burkholderia pseudomallei (B. pseudomallei) interacts with its host to elicit melioidosis symptoms. We established a murine acute-phase melioidosis model and used DNA microarray technology to investigate the global host/pathogen interaction. We compared the transcriptome of infected liver and spleen with uninfected tissues over an infection period of 42 hr to identify genes whose expression is altered in response to an acute infection.Results: Viable B. pseudomallei cells were consistently detected in the blood, liver and spleen during the 42 hr course of infection. Microarray analysis of the liver and spleen over this time course demonstrated that genes involved in immune response, stress response, cell cycle regulation, proteasomal degradation, cellular metabolism and signal transduction pathways were differentially regulated. Up regulation of toll-like receptor 2 (TLR2) gene expression suggested that a TLR2-mediated signalling pathway is responsible for recognition and initiation of an inflammatory response to the acute B. pseudomallei infection. Most of the highly elevated inflammatory genes are a cohort of "core host immune response" genes commonly seen in general inflammation infections. Concomitant to this initial inflammatory response, we observed an increase in transcripts associated with cell-death, caspase activation and peptidoglysis that ultimately promote tissue injury in the host. The complement system responsible for restoring host cellular homeostasis and eliminating intracellular bacteria was activated only after 24 hr post-infection. However, at this time point, diverse host nutrient metabolic and cellular pathways including glycolysis, fatty acid metabolism and tricarboxylic acid (TCA) cycle were repressed.Conclusions: This detailed picture of the host transcriptional response during acute melioidosis highlights a broad range of innate immune mechanisms that are activated in the host within 24 hrs, including the core immune response commonly seen in general inflammatory infections. Nevertheless, this activation is suppressed at 42 hr post-infection and in addition, suboptimal activation and function of the downstream complement system promotes uncontrolled spread of the bacteria. © 2010 Chin et al; licensee BioMed Central Ltd. Source


Hara Y.,Malaysia Genome Institute | Chin C.-Y.,National University of Malaysia | Chin C.-Y.,Emory University | Mohamed R.,National University of Malaysia | And 2 more authors.
BMC Infectious Diseases | Year: 2013

Background: Burkholderia pseudomallei, the causative agent of melioidosis, is endemic to Southeast Asia and northern Australia. Clinical manifestations of disease are diverse, ranging from chronic infection to acute septicaemia. The current gold standard of diagnosis involves bacterial culture and identification which is time consuming and often too late for early medical intervention. Hence, rapid diagnosis of melioidosis is crucial for the successful management of melioidosis.Methods: The study evaluated 4 purified B. pseudomallei recombinant proteins (TssD-5, Omp3, smBpF4 and Omp85) as potential diagnostic agents for melioidosis. A total of 68 sera samples from Malaysian melioidosis patients were screened for the presence of specific antibodies towards these proteins using enzyme-linked immunosorbent assay (ELISA). Sera from patients with various bacterial and viral infections but negative for B. pseudomallei, as well as sera from healthy individuals, were also included as non-melioidosis controls. The Mann Whitney test was performed to compare the statistical differences between melioidosis patients and the non-melioidosis controls.Results: TssD-5 demonstrated the highest sensitivity of 71% followed by Omp3 (59%), smBpF4 (41%) and Omp85 (19%). All 4 antigens showed equally high specificity (89-96%). A cocktail of all 4 antigens resulted in slightly reduced sensitivity of 65% but improved specificity (99%). Multiple-antigen ELISA provided improved sensitivity of 88.2% whilst retaining good specificity (96%). There was minimal reactivity with sera from healthy individuals proposing the utility of these antigens to demarcate diseased from non-symptomatic individuals in an endemic country.Conclusions: TssD-5 demonstrated high detection sensitivity and specificity and the results were obtained within a few hours compared to time consuming culture and IFAT methods commonly used in a clinical setting. The use of multiple-antigens resulted in improved sensitivity (88.2%) whilst maintaining superior specificity. These data highlight the use of TssD-5 and other recombinant antigens tested in this study as potential serodiagnostic agents for melioidosis. © 2013 Hara et al.; licensee BioMed Central Ltd. Source

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