Protease production by Burkholderia pseudomallei and virulence in mice.
ABSTRACT The aim of this study was to assess protease production and virulence of various Burkholderia pseudomallei strains. Protease activity was evaluated in filtrates from cultures grown for 50 h in TSB Dialysate by azocasein hydrolysis, and expressed as absorbancy at 405 nm. Virulence was assessed in 8 weeks old SWISS mice, by intraperitoneal injection of 6-6 x 10(5) CFU, and the LD50 was calculated after 30 days by the method of Reed and Muench. The lethal activity was studied for five strains of B. pseudomallei and the type strains of Burkholderia pseudomallei, Burkholderia mallei, and Burkholderia cepacia. The three type strains appeared to be low protease producers (A405 = 0.11, 0.09 and 0.00, respectively) and avirulent. The two more virulent B. pseudomallei strains exhibited significantly different LD50, 3.5 x 10(2) (IPP 6068 VIR) versus 2.1 x 10(5) CFU/mouse (40/97), and protease activities (A405 = 0.046 and 0.79, respectively). Moreover, the avirulent parent of IPP 6068 (AG), was a better protease producer than the 6068 VIR strain, A405 = 0.26 versus 0.046. These results suggest that there is no correlation between virulence and level of exoproteolytic activity, when B. pseudomallei is injected to mice via the intraperitoneal route.
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Article: Melioidosis: a case report.[Show abstract] [Hide abstract]
ABSTRACT: Burkhloderia pseudomallei has recently gained importance as an emerging pathogen in India. It causes various clinical manifestations like pneumoniae, septicaemia, arthritis, abscess etc. Cases have been reported from Southeast Asia mainly Thailand, Malaysia, Vietnam, etc. In India, few cases have been reported mainly from the southern part of the country. Patient was a 65-year-old male and presented with fever 1 month back, cough and breathlessness for same period, swelling on both ankles from 7 days. B. pseudomallei was isolated from endotracheal secretions, blood cultures, leg wound. He was successfully treated with Imipenem and Doxycycline and put on maintenance therapy now, and is currently doing well.Journal of global infectious diseases 04/2011; 3(2):183-6.
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ABSTRACT: Macrophage infectivity potentiators (Mips) are a group of virulence factors encoded by pathogenic bacteria such as Legionella, Chlamydia, and Neisseria species. Mips are part of the FK506-binding protein (FKBP) family, whose members typically exhibit peptidylprolyl cis-trans isomerase (PPIase) activity which is inhibitable by the immunosuppressants FK506 and rapamycin. Here we describe the identification and characterization of BPSS1823, a Mip-like protein in the intracellular pathogen Burkholderia pseudomallei. Recombinant BPSS1823 protein has rapamycin-inhibitable PPIase activity, indicating that it is a functional FKBP. A mutant strain generated by deletion of BPSS1823 in B. pseudomallei exhibited a reduced ability to survive within cells and significant attenuation in vivo, suggesting that BPSS1823 is important for B. pseudomallei virulence. In addition, pleiotropic effects were observed with a reduction in virulence mechanisms, including resistance to host killing mechanisms, swarming motility, and protease production.Infection and immunity 08/2011; 79(11):4299-307. · 4.21 Impact Factor
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ABSTRACT: Aims: The intracellular pathogen Burkholderia pseudomallei causes the disease melioidosis, a major source of morbidity and mortality in Southeast Asia and northern Australia. The need to develop novel antimicrobials is compounded by the absence of a licensed vaccine and the bacterium's resistance to multiple antibiotics. In a number of clinically relevant Gram negative pathogens, DsbA is the primary disulfide oxidoreductase responsible for catalysing the formation of disulfide bonds in secreted and membrane associated proteins. In this study, a putative B. pseudomallei dsbA gene was evaluated functionally and structurally and its contribution to infection assessed. Results: Biochemical studies confirmed the dsbA gene encodes a protein disulfide oxidoreductase. A DsbA deletion strain of B. pseudomallei was attenuated in both macrophages and a Balb/C mouse model of infection and displayed pleiotropic phenotypes that included defects in both secretion and motility. The 1.9 Å resolution crystal structure of BpsDsbA revealed differences from the classic member of this family E. coli DsbA, in particular within the region surrounding the active site disulfide where EcDsbA engages with its partner protein E. coli DsbB, indicating the interaction of BpsDsbA with its proposed partner BpsDsbB may be distinct from that of EcDsbA-EcDsbB. Innovation: This study has characterized BpsDsbA biochemically and structurally, and determined that it is required for virulence of B. pseudomallei. Conclusion: These data establish a critical role for BpsDbsA in B. pseudomallei infection, which in combination with our structural characterisation of BpsDsbA will facilitate the future development of rationally designed inhibitors against this drug resistant organism.Antioxidants & Redox Signaling 07/2013; · 8.20 Impact Factor