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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study has investigated the feasibility of a combination of recombinant surface layer (S-layer) proteins and empty bacterial cell envelopes (ghosts) to deliver candidate antigens for a vaccine against nontypeable Haemophilus influenzae (NTHi) infections. The S-layer gene sbsA from Bacillus stearothermophilus PV72 was used for the construction of fusion proteins. Fusion of maltose binding protein (MBP) to the N-terminus of SbsA allowed expression of the S-layer in the periplasm of Escherichia coli. The outer membrane protein (Omp) 26 of NTHi was inserted into the N-terminal and C-terminal regions of SbsA. The presence of the fused antigen Omp26 was demonstrated by Western blot experiments using anti-Omp26 antisera. Electron microscopy showed that the recombinant SbsA maintained the ability to self-assemble into sheet-like and cylindrical structures. Recombinant E. coli cell envelopes (ghosts) were produced by the expression of SbsA/Omp26 fusion proteins prior to gene E-mediated lysis. Intraperitoneal immunization with these recombinant bacterial ghosts induced an Omp26-specific antibody response in BALB/c mice. These results demonstrate that the NTHi antigen, Omp26, was expressed in the S-layer self-assembly product and this construct was immunogenic for Omp26 when administered to mice in bacterial cell envelopes.
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PMID:Construction of recombinant S-layer proteins (rSbsA) and their expression in bacterial ghosts--a delivery system for the nontypeable Haemophilus influenzae antigen Omp26. 1283 24

Recently, novel hybrid thiol peroxidase (TPx) proteins fused with a glutaredoxin (Grx) were found from some pathogenic bacteria, cyanobacteria, and anaerobic sulfur-oxidizing phototroph. The phylogenic tree analysis that was constructed from the aligned sequences showed two major branches. Haemophilus influenzae TPx.Grx was grouped in one branch as a 1-Cys subfamily of the thiol-specific antioxident protein/AhpC family. Most TPx.Grx proteins, including Vibrio cholerae TPx.Grx, were grouped in the 2-Cys subfamily. To explain the existence of two subgroups in novel hybrid TPx proteins, we have compared the kinetics given by V. cholerae TPx.Grx, H. influenzae TPx.Grx, their separated TPx domains, and a set of mutants devoid of the redox-active cysteines. The kinetic study described here demonstrates clearly that V. cholerae TPx.Grx is a 2-Cys TPx subfamily. For the first time, we also demonstrate the lipid peroxidase activity of V. cholerae TPx.Grx fusion and suggest the in vivo function of 2-Cys TPx.Grx fusion serving as a lipid peroxidase.
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PMID:Vibrio cholerae thiol peroxidase-glutaredoxin fusion is a 2-Cys TSA/AhpC subfamily acting as a lipid hydroperoxide reductase. 1470 41

Gram-negative bacterial autotransporter proteins are a growing group of virulence factors that are characterized by their ability to cross the outer membrane without the help of accessory proteins. A conserved C-terminal beta-domain is critical for targeting of autotransporters to the outer membrane and for translocation of the N-terminal "passenger" domain to the bacterial surface. We have demonstrated previously that the Haemophilus influenzae Hia adhesin belongs to the autotransporter family, with translocator activity residing in the C-terminal 319 residues. To gain further insight into the mechanism of autotransporter protein translocation, we performed a structure-function analysis on Hia. In initial experiments, we generated a series of in-frame deletions and a set of chimeric proteins containing varying regions of the Hia C terminus fused to a heterologous passenger domain and discovered that the final 76 residues of Hia are both necessary and sufficient for translocation. Analysis by flow cytometry revealed that the region N-terminal to this shortened translocator domain is surface localized, further suggesting that this region is not involved in beta-barrel formation or in translocation of the passenger domain. Western analysis demonstrated that the translocation-competent regions of the C terminus migrated at masses consistent with trimers, suggesting that the Hia C terminus oligomerizes. Furthermore, fusion proteins containing a heterologous passenger domain demonstrated that similarly small C-terminal regions of Yersinia sp. YadA and Neisseria meningitidis NhhA are translocation-competent. These data provide experimental support for a unique subclass of autotransporters characterized by a short trimeric translocator domain.
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PMID:The Haemophilus influenzae Hia autotransporter contains an unusually short trimeric translocator domain. 1472 37

In a phase I/II study, patients with solid metastatic MAGE-3-positive tumors, mainly melanoma, were vaccinated with recombinant MAGE-3 protein combined with the immunologic adjuvant AS02B comprised of MPL and QS21 in an oil-in-water emulsion. The recombinant MAGE-3 protein was made up of a partial sequence of the protein D (ProtD) antigen of Haemophilus influenzae fused to the MAGE-3 sequence. The vaccine was given intramuscularly at 3-week intervals. Patients whose tumors stabilized or regressed after 4 vaccinations received 2 additional vaccinations at 6-week intervals. MAGE-3 and ProtD antibody and cellular immune responses were monitored after vaccination. Ninety-six percent (23/24) of the patients vaccinated with MAGE-3 protein in AS02B adjuvant elicited a significant anti-MAGE-3 IgG antibody response after 4 vaccinations, and all developed anti-ProtD IgG antibodies. For the detection of T-cell activity, total peripheral blood mononuclear cells were restimulated in vitro with MAGE-3- or ProtD-loaded autologous mature dendritic cells. In 30% of the evaluable patients vaccinated with the adjuvanted recombinant protein, IFNgamma production was increased in response to MAGE-3, and 2 patients (14% of evaluable patients) had a concomitant increase in IL-5 production. In 37% and 43% of the patients, respectively, IFNgamma or IL-5 production was increased in response to ProtD. It is concluded that vaccination of advanced cancer patients with MAGE-3 self-antigen in AS02B adjuvant is able to elicit MAGE-3-specific antibody and a T-cell response.
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PMID:Immunologic analysis of a phase I/II study of vaccination with MAGE-3 protein combined with the AS02B adjuvant in patients with MAGE-3-positive tumors. 1477 84

Bordetella pertussis, the etiologic agent of whooping cough, is a highly infectious human pathogen capable of inducing mucosal and systemic immune responses upon a single intranasal administration. In an attenuated, pertussis toxin (PTX)-deficient recombinant form, it may therefore constitute an efficient bacterial vector that is particularly well adapted for the delivery of heterologous antigens to the respiratory mucosa. Filamentous hemagglutinin (FHA) has been used as a carrier to present foreign antigens at the bacterial surface, thereby inducing local, systemic, and protective immune responses to these antigens in mice. Both full-length and truncated (Fha44) forms of FHA have been used for antigen presentation. To investigate the effect of the carrier (FHA or Fha44) on antibody responses to passenger antigens, we genetically fused the HtrA protein of nontypeable Haemophilus influenzae to either FHA form. The fha-htrA and Fha44 gene-htrA hybrids were expressed as single copies inserted into the chromosome of PTX-deficient B. pertussis. Both chimeras were secreted into the culture supernatants of the recombinant strains and were recognized by anti-FHA and anti-HtrA antibodies. Intranasal infection with the strain producing the FHA-HtrA hybrid led to significantly higher anti-HtrA and anti-FHA antibody titers than those obtained in mice infected with the Fha44-HtrA-producing strain. Interestingly, the B. pertussis strain producing the Fha44-HtrA chimera colonized the mouse lungs more efficiently than the parental, Fha44-producing strain and gave rise to higher anti-FHA antibody titers than those induced by the parental strain.
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PMID:Production of nontypeable Haemophilus influenzae HtrA by recombinant Bordetella pertussis with the use of filamentous hemagglutinin as a carrier. 1597 22

Haemophilus somnus immunoglobulin binding proteins (IgBPs) are virulence associated but only one (p76) has been genetically defined. We determined the nucleotide sequence of the 5'-flanking region of the p76 gene. This region had been identified as the coding region for a series of high molecular weight (HMW)-IgBPs. Analysis of the nucleotide sequence indicated the gene (immunoglobulin binding protein A, ibpA) encoding the HMW and p76 IgBPs comprised a single open reading frame of 12,285 base pairs (bp). The ibpA gene is flanked by an upstream ORF of 1758bp, designated ibpB. The predicted amino acid sequences of these two genes demonstrate similarity to virulence exoproteins and their transporter proteins that comprise a two-partner secretion pathway in various Gram-negative bacteria. Motifs associated with binding to mammalian cells were also identified within the sequence. Competitive inhibition studies implicated a putative heparin-binding domain in adherence to bovine endothelial cells. Expression plasmids for glutathione S-transferase (GST)-fused recombinant fragments covered amino acid residues 972-3201. IgG2 Fc binding studies identified fragment 972-1515 (GST-IbpA3) as an Fc binding peptide. This peptide and GST-IbpA5 (aa 2071-2730) reacted strongly with convalescent phase serum. In a small preliminary study, calves immunized with the purified GST-IbpA3 peptide were protected against an intrabronchial H. somnus challenge.
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PMID:Genetic and functional analysis of Haemophilus somnus high molecular weight-immunoglobulin binding proteins. 1616 3

Simple sequence repeats located within reading frames mediate phase-variable ON/OFF switches in gene expression by generating frameshifts. Multiple translation initiation codons in different reading frames are found upstream of most Haemophilus influenzae tetranucleotide repeat tracts, raising the possibility of multiple active reading frames and more than two levels of gene expression for these loci. Phase variation between three levels of gene expression (strong, weak, and none) was observed when lic2A was fused to a lacZ reporter gene. The lic2A 5' CAAT repeat tract is preceded by four 5' ATG codons (x, y, z1, and z2) in two reading frames. Each of these initiation codons was inactivated by site-directed mutagenesis. Strong expression from frame 1 was associated with x but not y. Weak expression from frame 2 was mainly dependent on the z2 codon, and there was no expression from frame 3. Using monoclonal antibodies specific for a digalactoside epitope of lipopolysaccharide whose synthesis requires Lic2A, two levels (strong and undetectable) of antibody reactivity were detected, suggesting that weak expression of lic2A is not discernible at the phenotypic level. Inactivation of the x initiation codon resulted in loss of strong expression of the digalactoside epitope and elevated killing by human serum. The failure to detect more than two phenotypes for lic2A, despite clear evidence of weak expression from the z1/z2 initiation codons, leaves open the question of whether or not multiple initiation codons are associated with more complex patterns of phenotypic variation rather than classical phase-variable switching between two phenotypes.
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PMID:Identification of the functional initiation codons of a phase-variable gene of Haemophilus influenzae, lic2A, with the potential for differential expression. 1709 9

PAHs are aromatic hydrocarbons with two or more fused benzene rings with natural as well as anthropogenic sources. They are widely distributed environmental contaminants that have detrimental biological effects, toxicity, mutagenecity and carcinogenicity. Due to their ubiquitous occurrence, recalcitrance, bioaccumulation potential and carcinogenic activity, the PAHs have gathered significant environmental concern. Although PAH may undergo adsorption, volatilization, photolysis, and chemical degradation, microbial degradation is the major degradation process. PAH degradation depends on the environmental conditions, number and type of the microorganisms, nature and chemical structure of the chemical compound being degraded. They are biodegraded/biotransformed into less complex metabolites, and through mineralization into inorganic minerals, H(2)O, CO(2) (aerobic) or CH(4) (anaerobic) and rate of biodegradation depends on pH, temperature, oxygen, microbial population, degree of acclimation, accessibility of nutrients, chemical structure of the compound, cellular transport properties, and chemical partitioning in growth medium. A number of bacterial species are known to degrade PAHs and most of them are isolated from contaminated soil or sediments. Pseudomonas aeruginosa, Pseudomons fluoresens, Mycobacterium spp., Haemophilus spp., Rhodococcus spp., Paenibacillus spp. are some of the commonly studied PAH-degrading bacteria. Lignolytic fungi too have the property of PAH degradation. Phanerochaete chrysosporium, Bjerkandera adusta, and Pleurotus ostreatus are the common PAH-degrading fungi. Enzymes involved in the degradation of PAHs are oxygenase, dehydrogenase and lignolytic enzymes. Fungal lignolytic enzymes are lignin peroxidase, laccase, and manganese peroxidase. They are extracellular and catalyze radical formation by oxidation to destabilize bonds in a molecule. The biodegradation of PAHs has been observed under both aerobic and anaerobic conditions and the rate can be enhanced by physical/chemical pretreatment of contaminated soil. Addition of biosurfactant-producing bacteria and light oils can increase the bioavailability of PAHs and metabolic potential of the bacterial community. The supplementation of contaminated soils with compost materials can also enhance biodegradation without long-term accumulation of extractable polar and more available intermediates. Wetlands, too, have found an application in PAH removal from wastewater. The intensive biological activities in such an ecosystem lead to a high rate of autotrophic and heterotrophic processes. Aquatic weeds Typha spp. and Scirpus lacustris have been used in horizontal-vertical macrophyte based wetlands to treat PAHs. An integrated approach of physical, chemical, and biological degradation may be adopted to get synergistically enhanced removal rates and to treat/remediate the contaminated sites in an ecologically favorable process.
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PMID:Biodegradation aspects of polycyclic aromatic hydrocarbons (PAHs): a review. 1944 41

Tripartite ATP-independent periplasmic (TRAP) transporters are widespread in bacteria but poorly characterized. They contain three subunits, a small membrane protein, a large membrane protein, and a substrate-binding protein (SBP). Although the function of the SBP is well established, the membrane components have only been studied in detail for the sialic acid TRAP transporter SiaPQM from Haemophilus influenzae, where the membrane proteins are genetically fused. Herein, we report the first in vitro characterization of a truly tripartite TRAP transporter, the SiaPQM system (VC1777-1779) from the human pathogen Vibrio cholerae. The active reconstituted transporter catalyzes unidirectional Na(+)-dependent sialic acid uptake having similar biochemical features to the orthologous system in H. influenzae. However, using this tripartite transporter, we demonstrate the tight association of the small, SiaQ, and large, SiaM, membrane proteins that form a 1:1 complex. Using reconstituted proteoliposomes containing particular combinations of the three subunits, we demonstrate biochemically that all three subunits are likely to be essential to form a functional TRAP transporter.
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PMID:The membrane proteins SiaQ and SiaM form an essential stoichiometric complex in the sialic acid tripartite ATP-independent periplasmic (TRAP) transporter SiaPQM (VC1777-1779) from Vibrio cholerae. 2216 85

The haloacid dehalogenase enzyme superfamily (HADSF) is largely composed of phosphatases that have been particularly successful at adaptating to novel biological functions relative to members of other phosphatase families. Herein, we examine the structural basis for the divergence of function in two bacterial homologues: 2-keto-3-deoxy-d-manno-octulosonate 8-phosphate phosphohydrolase (KDO8P phosphatase, KDO8PP) and 2-keto-3-deoxy-9-O-phosphonononic acid phosphohydrolase (KDN9P phosphatase, KDN9PP). KDO8PP and KDN9PP catalyze the final step in KDO and KDN synthesis, respectively, prior to transfer to CMP to form the activated sugar nucleotide. KDO8PP and KDN9PP orthologs derived from an evolutionarily diverse collection of bacterial species were subjected to steady-state kinetic analysis to determine their specificities toward catalyzed KDO8P and KDN9P hydrolysis. Although each enzyme was more active with its biological substrate, the degree of selectivity (as defined by the ratio of kcat/Km for KDO8P vs KDN9P) varied significantly. High-resolution X-ray structure determination of Haemophilus influenzae KDO8PP bound to KDO/VO3(-) and Bacteriodes thetaiotaomicron KDN9PP bound to KDN/VO3(-) revealed the substrate-binding residues. The structures of the KDO8PP and KDN9PP orthologs were also determined to reveal the differences in their active-site structures that underlie the variation in substrate preference. Bioinformatic analysis was carried out to define the sequence divergence among KDN9PP and KDO8PP orthologs. The KDN9PP orthologs were found to exist as single-domain proteins or fused with the pathway nucleotidyl transferases; the fusion of KDO8PP with the transferase is rare. The KDO8PP and KDN9PP orthologs share a stringently conserved Arg residue that forms a salt bridge with the substrate carboxylate group. The split of the KDN9PP lineage from the KDO8PP orthologs is easily tracked by the acquisition of a Glu/Lys pair that supports KDN9P binding. Moreover, independently evolved lineages of KDO8PP orthologs exist, and are separated by diffuse active-site sequence boundaries. We infer a high tolerance of the KDO8PP catalytic platform to amino acid replacements that in turn influence substrate specificity changes and thereby facilitate the divergence in biological function.
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PMID:Structural basis for the divergence of substrate specificity and biological function within HAD phosphatases in lipopolysaccharide and sialic acid biosynthesis. 2384 98


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