Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ability of surfactant protein A (SP-A) to aggregate and opsonize type a and b Hemophilus influenzae was investigated. Type a, but not type b, was aggregated by SP-A. Aggregation was maximal at 24 micrograms SP-A/ml and was Ca(2+)-dependent. Aggregation of type a was inhibited by D-glucosyl-BSA but not by high concentrations of monosaccharides (D-mannose, D-galactose, D-glucose, or L-fucose) or by sialic acid, purified type a capsular polysaccharide, or type IV collagen. In Western blots, 125I-labeled SP-A bound to the major outer membrane protein (putatively P2) of type a hemophilus by a Ca(2+)-dependent mechanism. This binding was competitively inhibited by excess unlabeled SP-A. 125I-labeled SP-A also bound to the major membrane protein of type b, but at less than 5% of the level observed for type a. SP-A did not bind to lipooligosaccharides of either type a or type b. SP-A increased association of type a, but not type b, hemophilus with alveolar macrophages. After opsonization with SP-A, type a hemophilus were killed by alveolar macrophages, as indicated by bactericidal assays and the release of soluble, radiolabeled products from leukocytes. It is concluded that SP-A aggregated and opsonized type a hemophilus, but not type b, possibly because SP-A bound to the P2 outer membrane protein of type a to a greater extent.
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PMID:Aggregation and opsonization of type A but not type B Hemophilus influenzae by surfactant protein A. 801 34

Mannan-binding protein (MBP), a calcium-dependent plasma lectin, may play a role in the innate defence against microorganisms. After binding to carbohydrate structures at the bacterial surface, MBP activates the classical pathway of the complement system. To investigate the binding capacity of MBP to various bacteria associated with meningitis, an assay was developed to study the binding of MBP to bacteria grown in a semisynthetic fluid culture medium. Salmonella montevideo (containing a mannose-rich lipopolysaccharide (LPS)), used as a positive control strain, showed binding of radiolabelled MBP at a level of 80% compared with binding of MBP to zymosan. Binding of labelled MBP to Salm. montevideo was time-dependent, temperature-dependent and saturable. The binding was inhibited by unlabelled MBP, by mannose and by N-acetyl-D-glucosamine. Among bacterial pathogens often found to cause meningitis, a wide range of MBP binding capacities could be determined. The encapsulated Neisseria meningitidis (representatives from 11 serogroups other than group A were included: n = 22), N. mucosa (n = 1), Haemophilus influenzae type b (n = 10) and Streptococcus agalactiae (n = 5) had a low MBP binding capacity of 21.7% (95% confidence interval (CI) 3.3-40.1%). Escherichia coli K1 (n = 11), Strep. suis (n = 5), Strep. pneumoniae (n = 10) and N. meningitidis serogroup A (n = 2) showed intermediate MBP binding capacity of 58.4% (95% CI 40.0-76.8%). A third group consisting of non-encapsulated Listeria monocytogenes (n = 11), non-encapsulated H. influenzae (n = 2), non-encapsulated N. meningitidis (n = 2), N. cinera (n = 1) and N. subflava (n = 1) strains had a high MBP binding capacity of 87.5% (95% CI 62.5-112.5%). The majority of encapsulated pathogens causing bacterial meningitis seem to have a rather low MBP binding capacity.
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PMID:Binding of mannan-binding protein to various bacterial pathogens of meningitis. 808 95

The molecular basis for direct bacteria-macrophage interactions that distinguishes nontypeable (NT) Haemophilus influenzae from type b organisms is not known. Because of similarities between filamentous hemagglutinin (FHA) adhesin of Bordetella pertussis and high-molecular-weight (HMW) proteins commonly expressed by NT H. influenzae, the role that HMW proteins play in determining NT H. influenzae-macrophage interactions was assessed. In tests with genetically engineered organisms, HMW protein-expressing bacteria bound significantly better than isogenic HMW protein-deficient bacteria to macrophages. HMW protein-dependent binding to macrophages is trypsin-sensitive, is independent of divalent cations, does not occur via the leukocyte integrin CD11b/CD18, and is not affected by galactose-containing carbohydrates. Organisms bound via HMW proteins remain largely extracellular and viable. Like FHA of Bordetella organisms, HMW proteins mediate binding of NT H. influenzae to macrophages. However, unlike the interaction determined by FHA, this interaction is characteristically one of adhesion and requires additional serum opsonization for efficient killing of bacteria by macrophages.
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PMID:High-molecular-weight surface-exposed proteins of Haemophilus influenzae mediate binding to macrophages. 810 76

The outer membrane lipooligosaccharides (LOS) from Haemophilus influenzae type b strain A2 are a heterogeneous mixture of glycolipids containing a conserved Lipid A structure and a variable oligosaccharide moiety. After O-deacylation by treatment with anhydrous hydrazine, the O-deacylated LOS mixture was analyzed by electrospray mass spectrometry and shown to contain 11 components, ranging in M(r) from 2277.8 to 3416.4. The majority of these structures contained a variable number of hexoses, three L-glycero-D-manno-heptoses, and one 3-deoxy-D-manno-octulosonic acid (KDO) residue attached to a diphosphorylated O-deacylated Lipid A moiety. Additional phosphate and phosphoethanolamine (PEA) groups were also present on the oligosaccharide structures. Two minor high molecular weight components were also observed that contained N-acetylhexosamine and sialic acid. Neuraminidase treatment of the O-deacylated LOS mixture resulted in the loss of sialic acid from these latter two species. After mild acid hydrolysis and separation by size-exclusion chromatography, liquid secondary ion mass spectrometry identified six major and four minor oligosaccharides, ranging in M(r) from 1243.4 to 2215.8. These released oligosaccharides contained a common heptose trisaccharide core structure with anhydro-KDO at the reducing terminus, which arises as an artifact of the hydrolysis procedure by beta-elimination of a phosphate group from the 4-position of KDO. Selected oligosaccharide fractions were subjected to composition and methylation analyses and sequenced by tandem mass spectrometry. Taken together, these data defined the major O-deacylated LOS as follows: [formula: see text] Higher molecular weight structures in the mixture contained galactose, N-acetylglucosamine, and sialic acid as additional branch sugars, suggesting that H. influenzae A2 is capable of forming a sialylated lactosamine structure.
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PMID:Structural studies of the lipooligosaccharides from Haemophilus influenzae type b strain A2. 844 59

The enzyme UDP-galactose 4-epimerase (GalE) is involved in one of the major steps of galactose metabolism in bacteria. In many cases, GalE is required for the biosynthesis of extracellular polysaccharide materials such as lipopolysaccharide (LPS) and capsule. Mutants defective in galE have been shown to exhibit reduced virulence. Here we describe the cloning and characterization of the galE gene from the bovine pathogen Pasteurella haemolytica A1. This was achieved by the complementation of a Salmonella typhimurium galE mutant with a P. haemolytica A1 plasmid bank. Analysis of six clones recovered on minimal media with galactose as the carbon source showed that they all contained the same recombinant plasmid with a 5-kbp DNA insert. The galE-complementing activity was localized to a 2.2-kbp DNA region by subcloning. Biochemical, immunological, and phage sensitivity analyses of the recombinant LPS in S. typhimurium showed that it is essentially identical to that of the wild type. In vivo expression studies showed that a 37-kDa protein is expressed from the complementing plasmids, and the presence of GalE activity was confirmed by an assay for epimerase activity. Nucleotide sequence analysis of the cloned DNA identified the galE gene. Comparison of the deduced amino acid sequence analysis of P. haemolytica A1 GalE with published data showed high-level homology, 81.6%, with the GalE of Haemophilus influenzae type b. However, the sequences flanking galE do not show similarity with any other gal gene, suggesting that P. haemolytica A1 galE is not linked to the other genes of the gal operon, as is the case for Neisseria meningitidis, Neisseria gonorrhoeae, and H. influenzae. The separation of galE from the classical gal operon genes was confirmed by Southern blot hybridization studies, and a physical map showing the relative positions of galE, galT, and galK was constructed.
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PMID:Cloning and characterization of the galE locus of Pasteurella haemolytica A1. 864 92

Changes in intracellular cAMP concentration play important roles in Haemophilus influenzae, regulating both sugar utilization and competence for natural transformation. In enteric bacteria, cAMP levels are controlled by the phosphoenolpyruvate:glycose phosphotransferase system (PTS) in response to changes in availability of the preferred sugars it transports. We have demonstrated the existence of a simple PTS in H. influenzae by several methods. We have cloned the H. influenzae ptsI gene, encoding PTS Enzyme I; genome analysis locates it in a pts operon structurally homologous to those of enteric bacteria. In vitro phosphorylation assays confirmed the presence of functional PTS components. A ptsI null mutation reduced fructose uptake to 1% of the wild-type rate, and abolished fructose fermentation even when exogenous cAMP was provided. The ptsI mutation also prevented fermentation of ribose and galactose, but utilization of these cAMP-dependent sugars was restored by addition of cAMP. In wild-type cells the non-metabolizable fructose analogue xylitol prevented fermentation of these sugars, confirming that the fructose PTS regulates cAMP levels. Development of competence under standard inducing conditions was reduced 250-fold by the ptsI mutation, unless cells were provided with exogenous cAMP. Competence is thus shown to be under direct nutritional control by a fructose-specific PTS.
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PMID:Regulation of competence development and sugar utilization in Haemophilus influenzae Rd by a phosphoenolpyruvate:fructose phosphotransferase system. 888 65

Mouse monoclonal antibodies MAHI 4 and MAHI 10 reactive with Haemophilus influenzae lipopolysaccharide (LPS), were generated by fusing mouse myeloma cells with spleen cells of mice immunized with H. influenzae strain RM.7004-XP-1. The antibody MAHI 4 reacted in whole-cell enzyme immunoassay (EIA) and colony-dot-immunoblotting with 20 of 123 H. influenzae strains and to a few other human Haemophilus spp. and Neisseria spp., but not to any Bordetella pertussis, B. parapertussis, Aeromonas spp. or Moraxella catarrhalis strains tested. This suggests a specific epitope accessible to recognition in just a few strains. This conclusion was supported by the data on binding of MAHI 4 to only three of 18 H. influenzae LPSs tested, but not to any Haemophilus ducreyi or enterobacterial LPSs. The antibody MAHI 10 bound to 80 of 123 strains of H. influenzae and to a few strains of Neisseria spp. and M. catarrhalis as evaluated by EIA and colony-dot-immunoblotting, which suggests an epitope accessible to recognition in 65% of the H. influenzae strains tested. The antibody MAHI 10 reacted with 10 of 18 H. influenzae LPSs as determined by EIA. By using polysaccharides, obtained after both mild acidic hydrolysis, strong alkali treatment, and dephosphorylation, as inhibitors of the antibodies binding to H. influenzae LPS antigens it was shown that phosphate groups were essential for the binding of MAHI 10 to LPS but they did not affect antigenic recognition by MAHI 4. None of the monoclonal antibodies bound to isolated lipid A, but the aggregation caused by the fatty acids of lipid A was essential for optimum epitope recognition. Enzymatic treatment of homologous LPSs with galactose-oxidase led to products which were between 20 to 30 times less effective as inhibitors of the binding of the MAHI 4 than the native LPSs. Taken together the results indicate that MAHI 4 has the following pentasaccharide as the epitope Gal beta 1-->2 Hep alpha 1-->2Hep alpha 1-->3Hep alpha 1--> Kdo(P). These results emphasize the importance of the terminal beta-Gal residue in the definition of the MAHI 4 specificity, and of the terminal phosphorylated saccharide residues of some of the Haemophilus LPSs for the MAHI 10 specificity.
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PMID:Monoclonal antibodies against Haemophilus influenzae lipopolysaccharides: clone MAHI 4 binding to a pentasaccharide containing terminal beta-Gal residues and clone MAHI 10 recognizing terminal phosphorylated saccharide residues. 893 39

Phase variation in colony morphology has been associated with the pathogenesis of infection caused by Haemophilus influenzae. This study shows that differences in colony opacity in non-typeable H. influenzae (NTHi) strain H233 involve phase changes in the lipopolysaccharide (LPS) and depend on the expression of licl and lic2, which contain translational switches based on intragenic tandem repeats of 5'-CAAT-3'. Genetic analysis showed that opaque organisms have an out-of-frame number of repeats in both licl, required for the expression of phosphorylcholine (ChoP), and lic2, a putative galactosyl transferase that adds the terminal galactose on Galalpha1-4Gal. Defined variants in these loci were used to examine the contribution of individual LPS structures to resistance to serum bactericidal activity mediated by antibody and C-reactive protein (CRP). The addition of ChoP by licl was the only factor in serum killing involving CRP and complement. The terminal galactose moiety, in contrast, conferred resistance to killing by naturally acquired antibody and complement present in human serum. As Galalpha1-4Gal is also found on human glycolipids, it appears that decoration of the cell surface with this host-like antigen blocks antibody-mediated serum bactericidal activity. Genetic analysis of NTHi within the human respiratory tract demonstrated that Galalpha1-4Gal may not be expressed during carriage but may be advantageous for the organism in inflammatory states such as pneumonia.
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PMID:Adaptation of Haemophilus influenzae to acquired and innate humoral immunity based on phase variation of lipopolysaccharide. 1009 25

Haemophilus ducreyi is the etiologic agent of chancroid, a genital ulcer disease. The lipooligosaccharide (LOS) is considered to be a major virulence determinant and has been implicated in the adherence of H. ducreyi to keratinocytes. Strain A77, an isolate from the Paris collection, is serum sensitive, poorly adherent to fibroblasts, and deficient in microcolony formation. Structural analysis indicates that the LOS of strain A77 lacks the galactose residue found in the N-acetyllactosamine portion of the strain 35000HP LOS as well as the sialic acid substitution. From an H. ducreyi 35000HP genomic DNA library, a clone complementing the defect in A77 was identified by immunologic screening with monoclonal antibody (MAb) 3F11, a MAb which recognizes the N-acetyllactosamine portion of strain 35000HP LOS. The clone contained a 4-kb insert that was sequenced. One open reading frame which encodes a protein with a molecular weight of 33,400 was identified. This protein has homology to glycosyltransferases of Haemophilus influenzae, Haemophilus somnus, Neisseria species, and Pasteurella haemolytica. The putative H. ducreyi glycosyltransferase gene was insertionally inactivated, and an isogenic mutant of strain 35000HP was constructed. The most complex LOS glycoform produced by the mutant has a mobility on sodium dodecyl sulfate-polyacrylamide gel identical to that of the LOS of strain A77 and lacks the 3F11-binding epitope. Structural studies confirm that the most complex glycoform of the LOS isolated from the mutant lacks the galactose residue found in the N-acetyllactosamine portion of the strain 35000HP LOS. Although previously published data suggested that the serum-sensitive phenotype of A77 was due to the LOS mutation, we observed that the complemented A77 strain retained its serum-sensitive phenotype and that the galactosyltransferase mutant retained its serum-resistant phenotype. Thus, the serum sensitivity of strain A77 cannot be attributed to the galactosyltransferase mutation in strain A77.
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PMID:Cloning and characterization of the lipooligosaccharide galactosyltransferase II gene of Haemophilus ducreyi. 1073 74

Repetitive tetranucleotide sequences of 5'-(CAAT)(n)-3' have been identified at the 5' end of an open reading frame (ORF) named lob1 from Haemophilus somnus strain 738. Based on sequence analysis, lob1 has 59% DNA homology to lex2B, which is involved in lipooligosaccharide (LOS) biosynthesis in H. influenzae. We now report that the number of 5'-CAAT-3' repeats in lob1 varied from 31-35, but that 94% of colonies contained 33 repeats of 5'-CAAT-3' downstream of two potential start codons, as determined by DNA sequence analysis of the 5'-CAAT-3' region from individual colonies. If transcription began with the start codon closest to the 5'-CAAT-3' repeats, a protein of 34.5 kDa would be encoded when 33 repeats were present. However, we could not establish a correlation between the number of 5'-CAAT-3' repeats in lob1 with a specific LOS electrophoretic profile or reactivity with two LOS monoclonal antibodies, indicating multiple genes control LOS phase variation in H. somnus. Complementation of strain 129Pt with lob1 containing 33 5 '-CAAT-3' repeats in shuttle vector pLS88 resulted in transformants 129Pt(pLSlob1-33A) and 129Pt(pLSlob1-33B), both of which demonstrated the same altered LOS electrophoretic profile. Unlike strain 129Pt, both transformants underwent limited LOS phase variation, which correlated with variation in the number of 5'-CAAT-3' repeats in pLSlob1-33. Nanoelectrospray-mass spectrometry of O-deacylated LOS indicated that transformant 129Pt(pLSlob1-33A) LOS was composed of a different distribution of glycoforms than LOS of the parent strain. The ratio of glucose to galactose changed from 1:2 in strain 129Pt LOS to 2:1 in transformant 129Pt(pLSlob1-33A) LOS, as determined by gas chromatography-mass spectrometry. Nuclear magnetic resonance spectroscopy confirmed and extended these observations. Transformant 129Pt(pLSlob1-33A) was constitutively more reactive in colony immunoblotting to polyclonal antiserum made to purified strain 738 LOS, and was more susceptible to complement-mediated killing in the presence of anti-738 LOS serum than parent strain 129Pt. Based on these results, Lob1 appears to be a phase variable galactosyl transferase involved in LOS biosynthesis in H. somnus.
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PMID:Characterization of a DNA region containing 5'-(CAAT)(n)-3' DNA sequences involved in lipooligosaccharide biosynthesis in Haemophilus somnus. 1079 80


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