Regions important for the adhesin activity of Moraxella catarrhalis Hag

© 2007 Bullard et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Identification of Burkholderia mallei and Burkholderia pseudomallei adhesins for human respiratory epithelial cells

<p>Abstract</p> <p>Background</p> <p><it>Burkholderia pseudomallei </it>and <it>Burkholderia mallei </it>cause the diseases melioidosis and glanders, respectively. A well-studied aspect of pathogenesis by these closely-related bacteria is their ability to invade and multiply within eukaryotic cells. In contrast, the means by which <it>B. pseudomallei </it>and <it>B. mallei </it>adhere to cells are poorly defined. The purpose of this study was to identify adherence factors expressed by these organisms.</p> <p>Results</p> <p>Comparative sequence analyses identified a gene product in the published genome of <it>B. mallei </it>strain ATCC23344 (locus # BMAA0649) that resembles the well-characterized <it>Yersinia enterocolitica </it>autotransporter adhesin YadA. The gene encoding this <it>B. mallei </it>protein, designated <it>boaA</it>, was expressed in <it>Escherichia coli </it>and shown to significantly increase adherence to human epithelial cell lines, specifically HEp2 (laryngeal cells) and A549 (type II pneumocytes), as well as to cultures of normal human bronchial epithelium (NHBE). Consistent with these findings, disruption of the <it>boaA </it>gene in <it>B. mallei </it>ATCC23344 reduced adherence to all three cell types by ~50%. The genomes of the <it>B. pseudomallei </it>strains K96243 and DD503 were also found to contain <it>boaA </it>and inactivation of the gene in DD503 considerably decreased binding to monolayers of HEp2 and A549 cells and to NHBE cultures.</p> <p>A second YadA-like gene product highly similar to BoaA (65% identity) was identified in the published genomic sequence of <it>B. pseudomallei </it>strain K96243 (locus # BPSL1705). The gene specifying this protein, termed <it>boaB</it>, appears to be <it>B. pseudomallei</it>-specific. Quantitative attachment assays demonstrated that recombinant <it>E. coli </it>expressing BoaB displayed greater binding to A549 pneumocytes, HEp2 cells and NHBE cultures. Moreover, a <it>boaB </it>mutant of <it>B. pseudomallei </it>DD503 showed decreased adherence to these respiratory cells. Additionally, a <it>B. pseudomallei </it>strain lacking expression of both <it>boaA </it>and <it>boaB </it>was impaired in its ability to thrive inside J774A.1 murine macrophages, suggesting a possible role for these proteins in survival within professional phagocytic cells.</p> <p>Conclusions</p> <p>The <it>boaA </it>and <it>boaB </it>genes specify adhesins that mediate adherence to epithelial cells of the human respiratory tract. The <it>boaA </it>gene product is shared by <it>B. pseudomallei </it>and <it>B. mallei </it>whereas BoaB appears to be a <it>B. pseudomallei</it>-specific adherence factor.</p

The Advanced Microwave Precipitation Radiometer (AMPR) - Initial Results from the Integrated Precipitation Hydrology Experiment (IPHEx)

No abstract availabl

Characterization of the Moraxella catarrhalis uspA1 and uspA2 Genes and Their Encoded Products

The uspA1 and uspA2 genes of M. catarrhalis O35E encode two different surface-exposed proteins which were previously shown to share a 140-amino-acid region with 93% identity (C. Aebi, I. Maciver, J. L. Latimer, L. D. Cope, M. K. Stevens, S. E. Thomas, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun. 65:4367–4377, 1997). The N-terminal amino acid sequences of the mature forms of both UspA1 and UspA2 from strain O35E were determined after enzymatic treatment to remove the N-terminal pyroglutamyl residue that had blocked Edman degradation. Mass spectrometric analysis indicated that the molecular mass of UspA1 from M. catarrhalis O35E was 83,500 ± 116 Da. Nucleotide sequence analysis of the uspA1 and uspA2 genes from three other M. catarrhalis strains (TTA24, ATCC 25238, and V1171) revealed that the encoded protein products were very similar to those from strain O35E. Western blot analysis was used to confirm that each of these three strains of M. catarrhalis expressed both UspA1 and UspA2 proteins. Several different and repetitive amino acid motifs were present in both UspA1 and UspA2 from these four strains, and some of these were predicted to form coiled coils. Linear DNA templates were used in an in vitro transcription-translation system to determine the sizes of the monomeric forms of the UspA1 and UspA2 proteins from strains O35E and TTA24

Temporal development of the humoral immune response to surface antigens of Moraxella catarrhalis in young infants

The primary Moraxella catarrha/is-specific humoral immune response, and its association with nasopharyngeal colonization, was studied in a cohort of infants from birth to 2 years of age. Results indicated that the levels of antigen-specific IgG, IgA and IgM showed extensive inter-individual variability over time, with IgM and IgA levels to all 9 recombinant domains, from 7 different OMPs, being relatively low throughout the study period. In contrast, the level of antigen-specific IgG was significantly higher for the recombinant domains Hag(385-863), MID764-913, MID962-1200, UspA1(557-704) and UspA2(165-318) in cord blood compared to 6 months of age (P <= 0.001). This was a most likely a consequence of maternal transmission of antigen-specific IgG to newborn babies, possibly indicating a future role for these 3 surface antigens in the development of an effective humoral immune response to M. catarrhalis. Finally, at 2 years of age, the levels of antigen-specific IgG still remained far below that obtained from cord blood samples, indicating that the immune response to M. catarrhalis has not matured at 2 years of age. We provide evidence that a humoral antibody response to OMPs UspA1,UspA2 and Hag/MID may play a role in the immune response to community acquired M. catarrhalis colonization events. (C) 2011 Elsevier Ltd. All rights reserved

Novel Riboswitch Ligand Analogs as Selective Inhibitors of Guanine-Related Metabolic Pathways

Riboswitches are regulatory elements modulating gene expression in response to specific metabolite binding. It has been recently reported that riboswitch agonists may exhibit antimicrobial properties by binding to the riboswitch domain. Guanine riboswitches are involved in the regulation of transport and biosynthesis of purine metabolites, which are critical for the nucleotides cellular pool. Upon guanine binding, these riboswitches stabilize a 5′-untranslated mRNA structure that causes transcription attenuation of the downstream open reading frame. In principle, any agonistic compound targeting a guanine riboswitch could cause gene repression even when the cell is starved for guanine. Antibiotics binding to riboswitches provide novel antimicrobial compounds that can be rationally designed from riboswitch crystal structures. Using this, we have identified a pyrimidine compound (PC1) binding guanine riboswitches that shows bactericidal activity against a subgroup of bacterial species including well-known nosocomial pathogens. This selective bacterial killing is only achieved when guaA, a gene coding for a GMP synthetase, is under the control of the riboswitch. Among the bacterial strains tested, several clinical strains exhibiting multiple drug resistance were inhibited suggesting that PC1 targets a different metabolic pathway. As a proof of principle, we have used a mouse model to show a direct correlation between the administration of PC1 and the reduction of Staphylococcus aureus infection in mammary glands. This work establishes the possibility of using existing structural knowledge to design novel guanine riboswitch-targeting antibiotics as powerful and selective antimicrobial compounds. Particularly, the finding of this new guanine riboswitch target is crucial as community-acquired bacterial infections have recently started to emerge

Strategy for the management of diabetic macular edema: the European Vitreo-Retinal Society macular edema study

Objective. To compare the efficacy of different therapies in the treatment of diabetic macular edema (DME). Design. Nonrandomized, multicenter clinical study. Participants. 86 retina specialists from 29 countries provided clinical information on 2,603 patients with macular edema including 870 patients with DME. Methods. Reported data included the type and number of treatment(s) performed, the pre-and posttreatment visual acuities, and other clinical findings.The results were analyzed by the French INSEE (National Institute of Statistics and Economic Studies). Main Outcome Measures. Mean change of visual acuity and mean number of treatments performed. Results.The change in visual acuity over time in response to each treatment was plotted in second order polynomial regression trend lines. Intravitreal triamcinolone monotherapy resulted in some improvement in vision. Treatmentwith threshold or subthreshold grid laser also resulted in minimal vision gain. Anti-VEGF therapy resulted in more significant visual improvement. Treatment with pars plana vitrectomy and internal limiting membrane (ILM) peeling alone resulted in an improvement in vision greater than that observed with anti-VEGF injection alone. In our DME study, treatment with vitrectomy and ILM peeling alone resulted in the better visual improvement compared to other therapies

Studies on iron and pyocin transport in pseudomonas aeruginosa

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