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

A DNA amplification procedure using heat stable Taq polymerase and the polymerase chain reaction is described for the detection of Pseudomonas aeruginosa in specimens from cystic fibrosis patients. A set of primers was selected on the basis of the nucleotide sequence of the algD gene encoding GDP mannose dehydrogenase, a major enzyme in the biosynthesis of alginate by P. aeruginosa. Using this set of primers in conjunction with the polymerase chain reaction, P. aeruginosa could be specifically detected, with a sensitivity approximating 10 bacteria, in sputum harbouring large numbers of other respiratory pathogens, including Staphylococcus aureus and Haemophilus influenzae. These results suggest that amplification of specific sequences within the algD gene by the polymerase chain reaction may provide a highly sensitive and specific tool for the detection of P. aeruginosa in the early stages of pulmonary colonization.
Mol Cell Probes 1992 Aug
PMID:Detection of Pseudomonas aeruginosa in sputum from cystic fibrosis patients by the polymerase chain reaction. 152

Outer membrane protein P6 is an important antigen expressed on the surface of all strains of Haemophilus influenzae. The predicted amino acid sequence of P6 contains a region of alpha helices that shares sequence identity with a family of helix-turn-helix DNA-binding proteins. A search for sequence-specific binding sites that resemble an operator region within the gene revealed a sequence with striking homology to the consensus operator sequence for lambda Cro and repressor. To test the hypothesis that P6 binds its own gene, purified P6 on nitrocellulose was probed with plasmid DNA containing the P6 gene. P6 bound the P6 gene in this Southwestern blot assay. To further test the observation, gel shift analysis was performed. Gel shift assays using a P6-specific monoclonal antibody demonstrated that P6 in crude cell extracts binds to the region of the gene containing the putative binding site. Competition with a synthetic oligonucleotide corresponding to the putative binding site inhibited binding of P6 to the P6 gene on nitrocellulose and in the gel shift assay. In addition, this oligonucleotide bound directly to P6 on nitrocellulose. Finally, DNase footprinting confirmed that P6 bound specifically to the same region of the P6 gene. These results indicate that P6 binds to a sequence-specific site within its own gene, suggesting that P6 regulates its own expression. This represents the first example of a Gram-negative outer membrane protein binding to its own gene and has potentially important implications as a mechanism for regulation of expression of outer membrane antigens.
Mol Microbiol 1992 Feb
PMID:Outer membrane protein P6 of Haemophilus influenzae binds to its own gene. 156 Jul 83

Capsular polysaccharides of Gram-negative bacteria contribute to a large extent to the pathogenicity of these organisms. We show here that the molecular organization of the capsule gene loci in different serogroups of Neisseria meningitidis is similar to that of Haemophilus influenzae and Escherichia coli. A common molecular origin of the mechanisms of encapsulation is indicated by strong homology of the genes involved in transport of the capsular polysaccharides to the cell surface in all these organisms. The proteins involved in capsular polysaccharide transport fit the characteristics of ABC (ATP-binding cassette) transporters. Furthermore, by sequence comparison of the sialytransferases of N. meningitidis B and E. coli K1, the capsule of which is composed of alpha 2,8-linked polyneuraminic acid, a significant degree of homology was observed, indicating that the capsular polysaccharide type itself has the same evolutionary origin in these two pathogens.
Mol Microbiol 1991 May
PMID:Evidence for a common molecular origin of the capsule gene loci in gram-negative bacteria expressing group II capsular polysaccharides. 165 49

The population of capsulate Haemophilus influenzae is divided into two phylogenetic divisions. Here we show that in division I strains the capsulation (cap) gene cluster lies between direct repeats of a novel insertion sequence (IS)-like element, IS1016. cap has apparently been mobilized in the chromosome as a compound transposon by IS1016, and the repeats have provided a molecular substrate for reversible cap gene amplification, with augmentation of capsule production, through unequal homologous recombination. Such amplification has occurred in serotype b strains, but in these a large direct repeat of cap genes has become fixed in the population. We have found a 1.2 kb deletion at one end of this duplicated capb locus, removing most of one copy of the polysaccharide export gene bexA. We have shown that this makes capsulation dependent on preservation of the direct repeat structure in order to avoid recombination-mediated loss of the other copy of bexA. Type b strains with this cap configuration are disseminated worldwide and currently cause nearly all invasive Haemophilus infections, leading us to speculate that the 1.2 kb deletion occurred in an ancestral type b strain and conferred significant biological advantage.
Mol Microbiol 1991 Jun
PMID:The Haemophilus influenzae capsulation gene cluster: a compound transposon. 166 7

Size and antigenic heterogeneity have been recognized in both outer membrane protein P1 and outer membrane protein P2 of Haemophilus influenzae type b. To determine the molecular basis for these differences, we have cloned and sequenced the structural genes for OMPs P1 and P2 from prototype isolates with the OMP subtypes 1H, 3L and 6U. The nucleotide and derived amino acid sequences of the P1 genes are characterized by three variable regions dispersed between highly conserved regions. The nucleic acid and derived amino acid sequences of the P2 genes are also highly conserved. The P2 genes from OMP subtype 1H and 3L isolates are identical. The sequence of the 6U gene differs by 13 nucleotides, resulting in 10 amino acid changes.
Mol Immunol 1991 Mar
PMID:Comparison of the structure of the genes for outer membrane proteins P1 and P2 of Haemophilus influenzae type b. 167 26

We recently isolated a recombinant phage from a Haemophilus influenzae type b (Hib) library that assembles an oligosaccharide with an apparent molecular weight of 1400 (1.4 K) on a 4.1 K Escherichia coli lipopolysaccharide (LPS) structure, producing a 5.5 K LPS species that contains a KDO (2-keto-deoxyoctulosonic acid) epitope. Subcloning and deletional analysis of the 14 kb Haemophilus insert showed that three overlapping restriction fragments contained within a 7.2 kb Pstl-BamHl fragment sequentially modified an E. coli 4.1 K LPS structure, generating novel species of 4.5 K, 5.1 K and 5.5 K. Only the 5.5 K species contained the KDO epitope. We confirmed the relationship between the cloned genes and Hib lipooligosaccharide (LOS) biosynthesis by constructing a mutant that expressed an altered LOS. Thus, the Hib 7.2 kb Pstl-BamHl restriction fragment contained a cluster of at least three genetic loci whose products acted sequentially in LOS biosynthesis.
Mol Microbiol 1991 Oct
PMID:Analysis of Haemophilus influenzae type b lipooligosaccharide-synthesis genes that assemble or expose a 2-keto-3-deoxyoctulosonic acid epitope. 172 79

A prominent 19 kDa surface antigen of Legionella pneumophila, cloned in Escherichia coli, was found to be intimately associated with peptidoglycan. The DNA region encoding this antigen was mapped on an 11.9 kb plasmid by means of deletion analysis and transposon mutagenesis. PhoA+ gene fusions, gene-rated by TnphoA insertions into this region, confirmed the presence of a gene encoding a secreted protein. PhoA+ transposon insertions were also associated with loss of the 19 kDa antigen in immunoassays using a monoclonal antibody (mAb1E9) and the replacement of the 19 kDa antigen with larger fusion proteins in immunoblots using Legionella immune serum. A 1540bp PstI fragment carrying the gene was sequenced, and the open reading frame encoding the antigen was identified. The gene encodes a polypeptide 176 amino acid residues long and 18913Da in size. The presence of a signal sequence of 22 amino acids with a consensus sequence for cleavage by signal peptidase II indicates that the antigen is a lipoprotein, and striking similarity with peptidoglycan-associated lipoproteins (PALs) from E. coli (51% amino acid homology) and Haemophilus influenzae (55% homology) is noted. We conclude that the 19kDa antigen of L. pneumophila is the structural equivalent of the PAL found in other Gram-negative species and suggest that its post-translational acylation may explain its potency as an immunogen.
Mol Microbiol 1991 Aug
PMID:Characterization of a Legionella pneumophila gene encoding a lipoprotein antigen. 176 77

We describe the use of a DNA probe for genotyping clinical isolates of Haemophilus influenzae. The probe, containing capsulation genes, differentiates between the six Haemophilus serotypes in a Southern blotting procedure. It also hybridizes with a distinctive pattern to DNA from capsule-deficient mutants of serotype b strains, while failing to hybridize to DNA from typical clinical isolates of non-serotypable H. influenzae. The probe can thus resolve issues of serotyping uncertainty such as arise, for example, when capsulate strains are found to have lost reactivity with serotyping reagents after storage or transmission from one laboratory to another. The probe has proved useful in the evaluation of Haemophilus infections in infants following administration of H. influenzae type b vaccine. In an illustrative example, the probe was used to resolve serotyping ambiguity in a case of Haemophilus bacteraemia in a vaccine recipient, providing compelling evidence that the organism responsible was neither type b nor derived from a type b strain. The widespread introduction of vaccines against H. influenzae type b disease will increase the importance of the precise identification of strains infecting immunized children. This need can only be met by the development of 'gold standards' such as capsulation gene probes.
Mol Cell Probes 1991 Oct
PMID:Capsular typing of Haemophilus influenzae with a DNA probe. 179 58

Moraxella (Branhamella) catarrhalis is an aerobic Gram-negative diplococcus that is now recognized as a pathogen of the respiratory tract. Rapid and direct identification of this bacterium has become important to the clinical microbiology laboratory. Recently, rapid tests for the identification of Neisseria species and M. catarrhalis have been commercialized but they are primarily for Neisseriae; in these kits, M. catarrhalis is always identified presumptively. We have developed a DNA probe of chromosomal origin that is 100% specific for M. catarrhalis. The oligonucleotide probe was derived from a cloned Ase I chromosomal DNA fragment of M. catarrhalis that did not react with Haemophilus influenzae DNA in hybridization experiments. Three of the first 17 Ase I clones were selected randomly to be tested by colony hybridization against several different species that colonize the human respiratory tract. One of these three, pLQ121, has a 550 bp fragment inserted into pBR322 and was determined to be 100% specific to M. catarrhalis. This fragment was partially sequenced and a 30-mer oligonucleotide was synthesized from the sequence data. This probe was also shown to be 100% specific to the species.
Mol Cell Probes 1991 Feb
PMID:Development of a species-specific DNA probe for Moraxella (Branhamella) catarrhalis. 190 55

A chromosomal locus, lic3, one of several involved in lipopolysaccharide (LPS) biosynthesis by Haemophilus influenzae, was cloned and its DNA sequence determined. lic3 comprises four closely apposed open reading frames (ORFs). ORF1 includes tandem repeats of the tetramer CAAT and two start codons out of frame with each other are found upstream of the repeats. ORF1 encodes a protein with no known homologues. ORF2 encodes the UDP-galactose-4-epimerase (galE) gene. ORF3 encodes a hydrophobic protein with no known homologues. ORF4 encodes the adenylate kinase (adk) gene. A deletion/insertion mutation lacking the 3' end of ORF1, all of galE, and the 5' end of ORF3 was constructed in the parent Hib strain (RM7004). These mutants had a galE phenotype, as evidenced by galactose sensitivity, altered LPS when grown in the absence of exogenous galactose, and reduced virulence in infant rats.
Mol Microbiol 1991 May
PMID:Molecular analysis of a complex locus from Haemophilus influenzae involved in phase-variable lipopolysaccharide biosynthesis. 195 82


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