Displaying publications 1 - 20 of 25 in total

Abstract:
Sort:
  1. Zueter AR, Rahman ZA, Abumarzouq M, Harun A
    BMC Infect Dis, 2018 01 02;18(1):5.
    PMID: 29291714 DOI: 10.1186/s12879-017-2912-9
    BACKGROUND: Previous studies on the Burkholderia pseudomallei genetic diversity among clinical isolates from melioidosis-endemic areas have identified genetic factors contributing to differential virulence. Although it has been ruled out in Australian and Thai B. pseudomallei populations, it remains unclear whether B. pseudomallei sequence types (STs) correlate with disease in Malaysian patients with melioidosis.

    METHODS: In this study, multi-locus sequence typing (MLST) was performed on clinical B. pseudomallei isolates collected from Kelantan state of Malaysia, patients' clinical data were reviewed and then genotype-risk correlations were investigated.

    RESULTS: Genotyping of 83 B. pseudomallei isolates revealed 32 different STs, of which 13(40%) were novel. The frequencies of the STs among the 83 isolates ranged from 1 to 12 observations, and ST54, ST371 and ST289 were predominant. All non-novel STs reported in this study have also been identified in other Asian countries. Based on the MLST data analysis, the phylogenetic tree showed clustering of the STs with each other, as well as with the STs from Southeast Asia and China. No evidence for associations between any of B. pseudomallei STs and clinical melioidosis presentation was detected. In addition, the bacterial genotype clusters in relation with each clinical outcome were statistically insignificant, and no risk estimate was reported. This study has expanded the data for B. pseudomallei on MLST database map and provided insights into the molecular epidemiology of melioidosis in Peninsular Malaysia.

    CONCLUSION: This study concurs with previous reports concluding that infecting strain type plays no role in determining disease presentation.

    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity
  2. Zong Z, Wang X, Deng Y
    PMID: 27244959
    A previously healthy Chinese male working in Malaysia returned to China with high fever. A blood culture showed Burkholderia pseudomallei strain WCBP1. This isolate was sequenced, showing type, ST881, which appears to be present in Malaysia. WCP1 had unusual susceptibility to aminoglycosides and habored the Yersinia-like fimbrial gene cluster for virulence. The patient's condition deteriorated rapidly but he recovered after receiving meropenem and intensive care support. Melioidosis is a potential problem among Chinese imigrant workers with strains new to China being identified.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity
  3. Wong RR, Kong C, Lee SH, Nathan S
    Sci Rep, 2016 06 07;6:27475.
    PMID: 27273550 DOI: 10.1038/srep27475
    Toxins are believed to play a crucial role in Burkholderia pseudomallei pathogenicity, however to date, only a few have been identified. The discovery of additional toxic molecules is limited by the lack of a sensitive indicator of B. pseudomallei toxicity. Previously, from a whole genome transcriptome analysis of B. pseudomallei-infected Caenorhabditis elegans, we noted significant overexpression of a number of worm genes encoding detoxification enzymes, indicating the host's attempt to clear bacterial toxic molecules. One of these genes, ugt-29, a family member of UDP-glucuronosyltransferases, was the most robustly induced phase II detoxification gene. In this study, we show that strong induction of ugt-29 is restricted to infections by the most virulent species among the pathogens tested. We also noted that ugt-29 is activated upon disruption of host protein synthesis. Hence, we propose that UGT-29 could be a promising biosensor to detect B. pseudomallei toxins that compromise host protein synthesis. The identification of bactobolin, a polyketide-peptide hybrid molecule, as a toxic molecule of B. pseudomallei further verifies the utilization of this surveillance system to search for bacterial toxins. Hence, a ugt-29 based reporter should be useful in screening for other molecules that inhibit host protein synthesis.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  4. Vellasamy KM, Vasu C, Puthucheary SD, Vadivelu J
    Microb Pathog, 2009 Sep;47(3):111-7.
    PMID: 19524661 DOI: 10.1016/j.micpath.2009.06.003
    To evaluate the potential role of extracellular proteins in the pathogenicity and virulence of Burkholderia pseudomallei, the activities of several enzymes in the culture filtrates of nine clinical and six environmental isolates were investigated in vitro and in vivo in ICR strain of mice. The production of protease, phosphatase, phospholipase C, superoxide dismutase, catalase and peroxidase were detected in the culture filtrates of all the 15 isolates at different time points of growth 4-24h. Over time, activity of each enzyme at each time point varied. Profile of secretion was similar among the 15 isolates irrespective of source, that is clinical or environmental. Catalase, phosphatase and phospholipase C were found to be increased in 60-100% of the isolates post-passage in mice. In vivo inoculation studies in ICR mice demonstrated a wide difference in their ability to cause bacteraemia, splenic or external abscesses and mortality rate ranged from few days to several weeks.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  5. Tay TF, Maheran M, Too SL, Hasidah MS, Ismail G, Embi N
    Trop Biomed, 2012 Dec;29(4):551-67.
    PMID: 23202600
    The disease melioidosis, caused by the soil bacteria Burkholderia pseudomallei, often manifests as acute septicemia with high fatality. Glycogen synthase kinase-3β (GSK3β) plays a key role during the inflammatory response induced by bacteria. We used a murine model of acute melioidosis to investigate the effects of LiCl, a GSK3 inhibitor on experimental animal survivability as well as TNF-α, IL-1β, IFN-γ, IL-10 and IL-1Ra cytokine levels in blood, lung, liver and spleen of B. pseudomallei-infected mice. Our results showed that administration of 100 μg/g LiCl improved survivability of mice infected with 5 X LD50 of B. pseudomallei. Bacterial counts in spleen, liver and lungs of infected mice administered with LiCl were lower than non-treated controls. Our data also revealed that GSK3β is phosphorylated in the spleen, liver and lung of animals infected with B. pseudomallei. However in infected animals administered with LiCl, higher levels of pGSK3 were detected in the organs. Levels of proinflammatory cytokines (TNF-α, IL-1β and IFN-γ) and anti-inflammatory cytokines (IL-10 and IL-1Ra) in sera and organs tested were elevated significantly following B. pseudomallei infection. With GSK3β inhibition, pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1β) were significantly decreased in all the samples tested whilst the levels of anti-inflammatory cytokines, IL-10 (spleen and lung) and IL-1Ra (spleen, liver and sera) were further elevated. This study represents the first report implicating GSK3β in the modulation of cytokine production during B. pseudomallei infection thus reiterating the important role of GSK3β in the inflammatory response caused by bacterial pathogens.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  6. Su YC, Wan KL, Mohamed R, Nathan S
    Microbes Infect., 2008 Oct;10(12-13):1335-45.
    PMID: 18761419 DOI: 10.1016/j.micinf.2008.07.034
    Burkholderia pseudomallei is the etiological agent of melioidosis, a severe infectious disease of humans and animals. The role of the bacterium's proteins expressed in vivo during human melioidosis continues to remain an enigma. This study's aim was to identify B. pseudomallei target proteins that elicit the humoral immune response in infected humans. A small insert genomic expression library was constructed and immunoscreened to identify peptides that reacted exclusively with melioidosis patients' sera. Sero-positive clones expressing immunogenic peptides were sequenced and annotated, and shown to represent 109 proteins involved in bacterial cell envelope biogenesis, cell motility and secretion, transcription, amino acid, ion and protein metabolism, energy production, DNA repair and unknown hypothetical proteins. Western blot analysis of three randomly selected full-length immunogenic polypeptides with patients' sera verified the findings of the immunome screening. The patients' humoral immune response to the 109 proteins suggests the induction or significant upregulation of these proteins in vivo during human infection and thus may play a role in the pathogenesis of B. pseudomallei. Identification of B. pseudomallei immunogens has shed new light on the elucidation of the bacterium's pathogenesis mechanism and disease severity. These immunogens can be further evaluated as prophylactic and serodiagnostic candidates as well as drug targets.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  7. Shrestha N, Adhikari M, Pant V, Baral S, Shrestha A, Basnyat B, et al.
    BMC Infect Dis, 2019 Feb 19;19(1):176.
    PMID: 30782129 DOI: 10.1186/s12879-019-3793-x
    BACKGROUND: Melioidosis is a life-threatening infectious disease that is caused by gram negative bacteria Burkholderia pseudomallei. This bacteria occurs as an environmental saprophyte typically in endemic regions of south-east Asia and northern Australia. Therefore, patients with melioidosis are at high risk of being misdiagnosed and/or under-diagnosed in South Asia.

    CASE PRESENTATION: Here, we report two cases of melioidosis from Nepal. Both of them were diabetic male who presented themselves with fever, multiple abscesses and developed sepsis. They were treated with multiple antimicrobial agents including antitubercular drugs before being correctly diagnosed as melioidosis. Consistent with this, both patients were farmer by occupation and also reported travelling to Malaysia in the past. The diagnosis was made consequent to the isolation of B. pseudomallei from pus samples. Accordingly, they were managed with intravenous meropenem followed by oral doxycycline and cotrimoxazole.

    CONCLUSION: The case reports raise serious concern over the existing unawareness of melioidosis in Nepal. Both of the cases were left undiagnosed for a long time. Therefore, clinicians need to keep a high index of suspicion while encountering similar cases. Especially diabetic-farmers who present with fever and sepsis and do not respond to antibiotics easily may turn out to be yet another case of melioidosis. Ascertaining the travel history and occupational history is of utmost significance. In addition, the microbiologist should be trained to correctly identify B. pseudomallei as it is often confused for other Burkholderia species. The organism responds only to specific antibiotics; therefore, correct and timely diagnosis becomes crucial for better outcomes.

    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity
  8. See JX, Chandramathi S, Abdulla MA, Vadivelu J, Shankar EM
    PLoS Negl Trop Dis, 2017 Aug;11(8):e0005702.
    PMID: 28820897 DOI: 10.1371/journal.pntd.0005702
    BACKGROUND: Melioidosis is a neglected tropical disease endemic across South East Asia and Northern Australia. The etiological agent, Burkholderia pseudomallei (B.pseudomallei), is a Gram-negative, rod-shaped, motile bacterium residing in the soil and muddy water across endemic regions of the tropical world. The bacterium is known to cause persistent infections by remaining latent within host cells for prolonged duration. Reactivation of the recrudescent disease often occurs in elders whose immunity wanes. Moreover, recurrence rates in melioidosis patients can be up to ~13% despite appropriate antibiotic therapy, suggestive of bacterial persistence and inefficacy of antibiotic regimens. The mechanisms behind bacterial persistence in the host remain unclear, and hence understanding host immunity during persistent B. pseudomallei infections may help designing potential immunotherapy.

    METHODOLOGY/PRINCIPAL FINDINGS: A persistent infection was generated using a small-colony variant (SCV) and a wild-type (WT) B. pseudomallei in BALB/c mice via intranasal administration. Infected mice that survived for >60 days were sacrificed. Lungs, livers, spleens, and peripheral blood mononuclear cells were harvested for experimental investigations. Histopathological changes of organs were observed in the infected mice, suggestive of successful establishment of persistent infections. Moreover, natural killer (NK) cell frequency was increased in SCV- and WT-infected mice. We observed programmed death-1 (PD-1) upregulation on B cells of SCV- and WT-infected mice. Interestingly, PD-1 upregulation was only observed on NK cells and monocytes of SCV-infected mice. In contrast, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) downregulation was seen on NK cells of WT-infected mice, and on monocytes of SCV- and WT-infected mice.

    CONCLUSIONS/SIGNIFICANCE: The SCV and the WT of B. pseudomallei distinctly upregulated PD-1 expression on B cells, NK cells, and monocytes to dampen host immunity, which likely facilitates bacterial persistence. PD-1/PD-L1 pathway appears to play an important role in the persistence of B. pseudomallei in the host.

    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  9. Raja NS, Ahmed MZ, Singh NN
    J Postgrad Med, 2005 Apr-Jun;51(2):140-5.
    PMID: 16006713
    Infectious diseases account for a third of all the deaths in the developing world. Achievements in understanding the basic microbiology, pathogenesis, host defenses and expanded epidemiology of infectious diseases have resulted in better management and reduced mortality. However, an emerging infectious disease, melioidosis, is becoming endemic in the tropical regions of the world and is spreading to non-endemic areas. This article highlights the current understanding of melioidosis including advances in diagnosis, treatment and prevention. Better understanding of melioidosis is essential, as it is life-threatening and if untreated, patients can succumb to it. Our sources include a literature review, information from international consensus meetings on melioidosis and ongoing discussions within the medical and scientific community.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity
  10. Puthucheary SD, Puah SM, Chai HC, Thong KL, Chua KH
    J. Mol. Microbiol. Biotechnol., 2012;22(3):198-204.
    PMID: 22846664 DOI: 10.1159/000338985
    Burkholderia pseudomallei is the causative agent of melioidosis. We initiated this investigation with a virulent and an attenuated strain of B. pseudomallei. Pulsed-field gel electrophoresis was carried out initially for macrogenomic comparison of both strains of B. pseudomallei. However, the pulsotypes obtained were identical and therefore we applied a subtractive hybridization technique to distinguish and determine the possible differences between the two strains. Six virulence strain-specific DNA fragments were obtained and the encoding homolog proteins were identified as a xenobiotic-responsive element family of transcriptional regulator, a hypothetical protein, an unknown protein, a plasmid recombination enzyme, a regulatory protein and a putative hemolysin activator protein. A combination of at least three of these determinants was identified in 45 clinical isolates when screening was carried out with self-designed multiplex PCR targeting the six putative virulent determinants. Our data demonstrated that different combinations of the six putative virulence genes were present in the clinical isolates indicating their probable role in the pathogenesis of B. pseudomallei infections.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  11. Puah SM, Puthucheary SD, Wang JT, Pan YJ, Chua KH
    ScientificWorldJournal, 2014;2014:590803.
    PMID: 25215325 DOI: 10.1155/2014/590803
    The Gram-negative saprophyte Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease which is endemic in Southeast Asia and northern Australia. This bacterium possesses many virulence factors which are thought to contribute to its survival and pathogenicity. Using a virulent clinical isolate of B. pseudomallei and an attenuated strain of the same B. pseudomallei isolate, 6 genes BPSL2033, BP1026B_I2784, BP1026B_I2780, BURPS1106A_A0094, BURPS1106A_1131, and BURPS1710A_1419 were identified earlier by PCR-based subtractive hybridization. These genes were extensively characterized at the molecular level, together with an additional gene BPSL3147 that had been identified by other investigators. Through a reverse genetic approach, single-gene knockout mutants were successfully constructed by using site-specific insertion mutagenesis and were confirmed by PCR. BPSL2033::Km and BURPS1710A_1419::Km mutants showed reduced rates of survival inside macrophage RAW 264.7 cells and also low levels of virulence in the nematode infection model. BPSL2033::Km demonstrated weak statistical significance (P = 0.049) at 8 hours after infection in macrophage infection study but this was not seen in BURPS1710A_1419::Km. Nevertheless, complemented strains of both genes were able to partially restore the gene defects in both in vitro and in vivo studies, thus suggesting that they individually play a minor role in the virulence of B. pseudomallei.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  12. Puah SM, Puthucheary SD, Chua KH
    Int J Med Sci, 2013;10(5):539-47.
    PMID: 23532805 DOI: 10.7150/ijms.5516
    The search for novel immunogenic polypeptides to improve the accuracy and reliability of serologic diagnostic methods for Burkholderia pseudomallei infection is ongoing. We employed a rapid and efficient approach to identify such polypeptides with sera from melioidosis patients using a small insert genomic expression library created from clinically confirmed local virulent isolates of B. pseudomallei. After 2 rounds of immunoscreening, 6 sero-positive clones expressing immunogenic peptides were sequenced and their identities were: benzoate 1,2-dioxygenase beta subunit, a putative 200 kDa antigen p200, phosphotransferase enzyme family protein, short chain dehydrogenase and 2 hypothetical proteins. These immunogens were then transferred to an ELISA platform for further large scale screening. By combining shotgun expression library and ELISA assays, we identified 2 polypeptides BPSS1904 (benzoate 1,2-dioxygenase beta subunit) and BPSL3130 (hypothetical protein), which had sensitivities of 78.9% and 79.4% and specificities of 88.1% and 94.8%, respectively in ELISA test, thus suggesting that both are potential candidate antigens for the serodiagnosis of infections caused by B. pseudomallei.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity
  13. Perumal Samy R, Stiles BG, Sethi G, Lim LHK
    PLoS Negl Trop Dis, 2017 May;11(5):e0004738.
    PMID: 28493905 DOI: 10.1371/journal.pntd.0004738
    This review briefly summarizes the geographical distribution and clinical impact of melioidosis, especially in the tropics. Burkholderia pseudomallei (a gram-negative bacterium) is the major causative agent for melioidosis, which is prevalent in Singapore, Malaysia, Thailand, Vietnam, and Northern Australia. Melioidosis patients are increasingly being recognized in other parts of the world. The bacteria are intrinsically resistant to many antimicrobial agents, but prolonged treatment, especially with combinations of antibiotics, may be effective. Despite therapy, the overall case fatality rate of septicemia in melioidosis remains significantly high. Intracellular survival of the bacteria within macrophages may progress to chronic infections, and about 10% of patients suffer relapses. In the coming decades, melioidosis will increasingly afflict travelers throughout many global regions. Clinicians managing travelers returning from the subtropics or tropics with severe pneumonia or septicemia should consider acute melioidosis as a differential diagnosis. Patients with open skin wounds, diabetes, or chronic renal disease are at higher risk for melioidosis and should avoid direct contact with soil and standing water in endemic regions. Furthermore, there are fears that B. pseudomallei may be used as a biological weapon. Technological advancements in molecular diagnostics and antibiotic therapy are improving the disease outcomes in endemic areas throughout Asia. Research and development efforts on vaccine candidates against melioidosis are ongoing.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  14. Ooi SK, Lim TY, Lee SH, Nathan S
    Virulence, 2012 Oct 01;3(6):485-96.
    PMID: 23076282 DOI: 10.4161/viru.21808
    The nematode Caenorhabditis elegans is hypersusceptible to Burkholderia pseudomallei infection. However, the virulence mechanisms underlying rapid lethality of C. elegans upon B. pseudomallei infection remain poorly defined. To probe the host-pathogen interaction, we constructed GFP-tagged B. pseudomallei and followed bacterial accumulation within the C. elegans intestinal lumen. Contrary to slow-killing by most bacterial pathogens, B. pseudomallei caused fairly limited intestinal lumen colonization throughout the period of observation. Using grinder-defective mutant worms that allow the entry of intact bacteria also did not result in full intestinal lumen colonization. In addition, we observed a significant decline in C. elegans defecation and pharyngeal pumping rates upon B. pseudomallei infection. The decline in defecation rates ruled out the contribution of defecation to the limited B. pseudomallei colonization. We also demonstrated that the limited intestinal lumen colonization was not attributed to slowed host feeding as bacterial loads did not change significantly when feeding was stimulated by exogenous serotonin. Both these observations confirm that B. pseudomallei is a poor colonizer of the C. elegans intestine. To explore the possibility of toxin-mediated killing, we examined the transcription of the C. elegans ABC transporter gene, pgp-5, upon B. pseudomallei infection of the ppgp-5::gfp reporter strain. Expression of pgp-5 was highly induced, notably in the pharynx and intestine, compared with Escherichia coli-fed worms, suggesting that the host actively thwarted the pathogenic assaults during infection. Collectively, our findings propose that B. pseudomallei specifically and continuously secretes toxins to overcome C. elegans immune responses.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  15. Nathan S, Li H, Mohamed R, Embi N
    J. Biochem. Mol. Biol. Biophys., 2002 Feb;6(1):45-53.
    PMID: 12186782
    We have used the phagemid pComb3H to construct recombinant phages displaying the single chain variable fragment (ScFv) towards exotoxin of Burkholderia pseudomallei. Variable heavy and light chain fragments were amplified from the hybridoma 6E6A8F3B line, with a wide spectrum of primers specific to mouse antibody genes. Through overlapping extension polymerase chain reaction, the heavy and light chain fragments were linked to form the ScFv which was subsequently cloned into the phage display vector and transformed into ER2537 cells to yield a complexity of 10(8) clones. The transformants were screened by four rounds of biopanning against the exotoxin and resulted in selective enrichment of exotoxin-binding antibodies by 301 fold. The phage pool from the final round of selection displayed antibodies of high-affinity to the exotoxin as demonstrated by ELISA. Several clones were selected randomly from this pool and analysed by restriction enzyme digestion, fingerprinting and sequencing. Restriction analysis confirmed that all clones carried a 700-800 bp insert whose sequences, in general, corresponded to that of mouse IgG. Fingerprinting profiles delineated the antibodies into two families with different CDR sequences.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity
  16. Mariappan V, Vellasamy KM, Barathan M, Girija ASS, Shankar EM, Vadivelu J
    Front Immunol, 2021;12:718719.
    PMID: 34456925 DOI: 10.3389/fimmu.2021.718719
    Burkholderia pseudomallei (B. pseudomallei) causes melioidosis, a potentially fatal disease for which no licensed vaccine is available thus far. The host-pathogen interactions in B. pseudomallei infection largely remain the tip of the iceberg. The pathological manifestations are protean ranging from acute to chronic involving one or more visceral organs leading to septic shock, especially in individuals with underlying conditions similar to COVID-19. Pathogenesis is attributed to the intracellular ability of the bacterium to 'step into' the host cell's cytoplasm from the endocytotic vacuole, where it appears to polymerize actin filaments to spread across cells in the closer vicinity. B. pseudomallei effectively evades the host's surveillance armory to remain latent for prolonged duration also causing relapses despite antimicrobial therapy. Therefore, eradication of intracellular B. pseudomallei is highly dependent on robust cellular immune responses. However, it remains ambiguous why certain individuals in endemic areas experience asymptomatic seroconversion, whereas others succumb to sepsis-associated sequelae. Here, we propose key insights on how the host's surveillance radars get commandeered by B. pseudomallei.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity
  17. Mariappan V, Thimma J, Vellasamy KM, Shankar EM, Vadivelu J
    Environ Microbiol Rep, 2018 04;10(2):217-225.
    PMID: 29393577 DOI: 10.1111/1758-2229.12624
    Physiological constituents in airway surface liquids (ASL) appear to impact the adherence and invasion potentials of Burkholderia pseudomallei contributing to recrudescent melioidosis. Here, we investigated the factors present in ASL that is likely to influence bacterial adhesion and invasion leading to improved understanding of bacterial pathogenesis. Six B. pseudomallei clinical isolates from different origins were used to investigate the ability of the bacteria to adhere and invade A549 human lung epithelial cells using a system that mimics the physiological ASL with different pH, NaCl, KCl, CaCl2 and glucose concentrations. These parameters resulted in markedly differential adherence and invasion abilities of B. pseudomallei to the lung epithelial cells. The concentration of 20 mM glucose dramatically increased adherence and invasion by increasing the rate of pili formation in depiliated bacteria. Glucose significantly increased adherence and invasion of B. pseudomallei to A549 cells, and presence of NaCl, KCl and CaCl2 markedly ablated the effect despite the presence of glucose. Our data established a link between glucose, enhanced adhesion and invasion potentials of B. pseudomallei, hinting increased susceptibility of individuals with diabetes mellitus to clinical melioidosis.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity
  18. Lee SH, Ooi SK, Mahadi NM, Tan MW, Nathan S
    PLoS One, 2011;6(3):e16707.
    PMID: 21408228 DOI: 10.1371/journal.pone.0016707
    Burkholderia pseudomallei is the causative agent of melioidosis, a disease of significant morbidity and mortality in both human and animals in endemic areas. Much remains to be known about the contributions of genotypic variations within the bacteria and the host, and environmental factors that lead to the manifestation of the clinical symptoms of melioidosis.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  19. Lee SH, Wong RR, Chin CY, Lim TY, Eng SA, Kong C, et al.
    Proc Natl Acad Sci U S A, 2013 Sep 10;110(37):15067-72.
    PMID: 23980181 DOI: 10.1073/pnas.1311725110
    Burkholderia pseudomallei is a Gram-negative soil bacterium that infects both humans and animals. Although cell culture studies have revealed significant insights into factors contributing to virulence and host defense, the interactions between this pathogen and its intact host remain to be elucidated. To gain insights into the host defense responses to B. pseudomallei infection within an intact host, we analyzed the genome-wide transcriptome of infected Caenorhabditis elegans and identified ∼6% of the nematode genes that were significantly altered over a 12-h course of infection. An unexpected feature of the transcriptional response to B. pseudomallei was a progressive increase in the proportion of down-regulated genes, of which ELT-2 transcriptional targets were significantly enriched. ELT-2 is an intestinal GATA transcription factor with a conserved role in immune responses. We demonstrate that B. pseudomallei down-regulation of ELT-2 targets is associated with degradation of ELT-2 protein by the host ubiquitin-proteasome system. Degradation of ELT-2 requires the B. pseudomallei type III secretion system. Together, our studies using an intact host provide evidence for pathogen-mediated host immune suppression through the destruction of a host transcription factor.
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
  20. Kang WT, Vellasamy KM, Chua EG, Vadivelu J
    J Infect Dis, 2015 Mar 1;211(5):827-34.
    PMID: 25165162 DOI: 10.1093/infdis/jiu492
    OBJECTIVES: The bsa locus of Burkholderia pseudomallei encodes several proteins that are components of the type III secretion system (TTSS). BipC was postulated as one of the TTSS-3 effector proteins, but its role in the pathogenesis of B. pseudomallei infection is not well understood. Thus, the aim of this study was to determine its role(s) in the virulence of B. pseudomallei pathogenesis.
    METHODS: A bipC TTSS-3-deficient strain of B. pseudomallei and complemented strains were generated to assess the role of BipC as a type III translocation apparatus. Human cell lines and a mouse model of melioidosis were used for in vitro and in vivo assays, respectively.
    RESULTS: A significant 2-fold reduction was demonstrated in the percentage of adherence, invasion, intracellular survival, and phagosomal escape of the bipC mutant. Interestingly, microscopic studies have shown that BipC was capable of delayed B. pseudomallei actin-based motility. The virulence of the mutant strain in a murine model of melioidosis demonstrated that the bipC mutant was less virulent, compared with the wild type.
    CONCLUSION: The results suggested that BipC possesses virulence determinants that play significant roles in host cell invasion and immune evasion.
    KEYWORDS: BipC; Burkholderia pseudomallei; host cell invasion; type III secretion system; type III translocation apparatus; virulence
    Matched MeSH terms: Burkholderia pseudomallei/pathogenicity*
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links