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)

Chimpanzee secretory immunoglobulin A (SIgA) was separated into two fractions by chromatography using the terminal galactose-binding lectin Jacalin. The SIgA fraction bound by Jacalin was cleaved by Haemophilus influenzae IgA1 protease, whereas the SIgA nonbinding fraction was not cleaved. It is proposed that these fractions represent IgA1 and IgA2 subclasses because the presence or absence of galactose-terminal oligosaccharides (Jacalin binding) and susceptibility or resistance to IgA1 protease are properties that define human IgA1 and IgA2 subclasses.
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PMID:Identification of two subclasses of IgA in the chimpanzee (Pan troglodytes). 140 36

This study examined the effect of immunoglobulin A (IgA) and the IgA-binding lectin jacalin on the phagocytosis of type II group B streptococci (GBS). Strains possessing the trypsin-sensitive and trypsin-resistant components of the c protein (II/c) and type II GBS lacking the c protein (II) were examined by radiolabeled bacterial uptake, bactericidal assays, and electron microscopy. Type II/c GBS resisted phagocytosis by monocytes (4.9% +/- 0.8% uptake, mean +/- SE, n = 25) compared with type II GBS (8.5% +/- 1.4% uptake, n = 14, P = 0.03). Phagocytic killing by polymorphonuclear leukocytes was also less for the type II/c strain 78-471 than for the type II strain 79-176 (68% +/- 5% versus 86% +/- 4% reduction in CFU at 45 min, P = 0.03). IgA binding did not explain the resistance of type II/c GBS to phagocytosis. The uptake of type II/c GBS was not significantly different after opsonization in cord sera lacking endogenous IgA (5.93% +/- 1.4%) than in the same cord sera after addition of exogenous IgA (5.48% +/- 1.4%, P = 0.69, n = 9). Attempts to remove serum IgA with the IgA-binding lectin jacalin resulted in the binding of IgA-jacalin complexes to II/c GBS. This combination of nonspecific IgA and jacalin increased uptake of II/c GBS from 4.9% +/- 0.8% to 11.8% +/- 1.9% (P = 0.002). Jacalin also combined with specific, immune, monoclonal IgA bound to the surface of Haemophilus influenzae and promoted the uptake of these bacteria. Jacalin and IgA mediated phagocytosis of II/c GBS via receptors that were not dependent on divalent cations and that were not modulated by plating monocytes on antigen-antibody complexes.
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PMID:Opsonic effect of jacalin and human immunoglobulin A on type II group B streptococci. 222 38

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

Mannose-binding lectin (MBL) is a collagenous serum lectin believed to be of importance in innate immunity. Genetically determined low levels of the protein are known to predispose to infections. In this study the binding of purified MBL to pathogens isolated from immunocompromised children was investigated by flow cytometry. Diverse Candida species, Aspergillus fumigatus, Staphylococcus aureus, and beta-hemolytic group A streptococci exhibited strong binding of MBL, whereas Escherichia coli, Klebsiella species, and Haemophilus influenzae type b were characterized by heterogeneous binding patterns. In contrast, beta-hemolytic group B streptococci, Streptococcus pneumoniae, and Staphylococcus epidermidis showed low levels of binding. Bound MBL was able to promote C4 deposition in a concentration-dependent manner. We conclude that MBL may be of importance in first-line immune defense against several important pathogens.
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PMID:Mannose-binding lectin binds to a range of clinically relevant microorganisms and promotes complement deposition. 1063 34

Specific 3'-sulfogalactolipid [SGL-sulfogalactosyl ceramide (SGCer) and sulfogalactosylglycerolipid (SGG)] binding is compared for hsp70s cloned from Helicobacter pylori, Haemophilus influenzae, Chlamydia trachomatis serovar E, Escherichia coli, murine male germ cells, and the hsp70-like extracellular domain within the sperm receptor from Strongylocentrotus purpuratus. This lectin activity, conserved among the different hsp70 family members, is modulated by the SGL aglycone. This is shown by differential binding to both SGC fatty acid homologues and 3'-sulfogalactolipid neoglycoproteins generated by coupling bovine serum albumin (BSA) and glycosyl ceramide acids synthesized by oxidation of the double bond of sphingosine. Eukaryotic hsp70s preferentially bound the SGCer fatty acid homologues SG(24)Cer, SG(18)Cer, and SG(20:OH)Cer, while prokaryotic hsp70s bound SG(18:1)Cer and SG(20:OH)Cer. Eukaryotic hsp70s bound SGCer-BSA and SG(24)Cer-BSA conjugates where the latter is the main constituent in SGCer-BSA, while prokaryotic hsp70s bound SG(20:OH)Cer-BSA. None of the hsp70s bound sulfogalactosyl sphingosine (SGSph) or SGSph-BSA, further demonstrating the important role of the aglycone. Although the primary SGL recognition domain of all hsp70s is conserved, we propose that aglycone organization differentially influences the interaction with the sub-site. Heterogeneous SGCer aglycone isoforms in cells and the differential in vitro binding of eukaryotic and prokaryotic hsp70s may relate to their different adhesin roles in vivo as mediators of germ cell and bacterial/host interactions, respectively.
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PMID:Hsp70s contain a specific sulfogalactolipid binding site. Differential aglycone influence on sulfogalactosyl ceramide binding by recombinant prokaryotic and eukaryotic hsp70 family members. 1129 23

The majority of infectious diseases are initiated by adhesion of pathogenic organisms to the tissues of the host. In many cases, this adhesion is mediated by lectins present on the surface of the infectious organism that bind to complementary carbohydrates on the surface of the host tissues. Lectin-deficient mutants often lack ability to initiate infection. Soluble carbohydrates recognized by the bacterial lectins block the adhesion of the bacteria to animal cells in vitro. Moreover, they have also been shown to protect against experimental infection by lectin-carrying bacteria in different organs of mammals such as mice, rabbits, calves and monkeys. In a phase II clinical trial, a pentasaccharide shown to have anti-adhesive activity against Streptococcus pneumoniae and Hemophilus influenzae in vitro failed to protect young children from nasopharyngeal colonization with these organisms and from developing otitis media. This could be because insufficient drug was delivered via nasal spray, because bacteria express multiple specificities, the inhibition of which may require a cocktail of oligosaccharides, or because children have different carbohydrate receptors from those of adults. The results of a clinical trial in which N-acetylneuraminyl(alpha2-3)lactose was administered orally to Helicobacter pylori positive patients in an effort to reduce or eradicate bacterial colonization, are awaited with interest. Although the high cost of production of the required oligosaccharides is falling with the recent introduction of enzymatic methods of synthesis, new technologies, in particular the use of engineered bacteria, promise to lower it even further. Attachment of the oligosaccharides to soluble polymeric carriers will increase greatly their effectiveness as antiadhesion agents. There is no doubt that anti-adhesive oligosaccharides will in the near future join the arsenal of drugs for the therapy of bacterial diseases.
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PMID:Safe as mother's milk: carbohydrates as future anti-adhesion drugs for bacterial diseases. 1142 56

Haemophilus somnus isolates from cases of thrombotic meningoencephalitis, pneumonia, and other disease sites are capable of undergoing a high rate of phase variation in the oligosaccharide component of their lipooligosaccharides (LOS). In contrast, the LOS of commensal strains isolated from the normal reproductive tract phase vary little or not at all. In addition, the LOS of H. somnus shares conserved epitopes with LOS from Neisseria gonorrhoeae, Haemophilus influenzae, and other species that can incorporate sialic acid into their LOS. We now report that growth of disease isolates of H. somnus with CMP-N-acetylneuraminic acid (CMP-NeuAc) or NeuAc added to the medium resulted in incorporation of NeuAc into the LOS. However, NeuAc was not incorporated into the LOS of commensal isolates and one disease isolate following growth in medium containing CMP-NeuAc or NeuAc. Sialylated LOS was detected by an increase in the molecular size or an increase in the amount of the largest-molecular-size LOS electrophoretic bands, which disappeared following treatment with neuraminidase. Sialylated LOS could also be detected by reactivity with Limax flavus agglutinin lectin, which is specific for sialylated species, by dot blot assay; this reactivity was also reversed by neuraminidase treatment. H. somnus strain 2336 LOS was found to contain some sialic acid when grown in medium lacking CMP-NeuAc or NeuAc, although supplementation enhanced NeuAc incorporation. In contrast strain 738, an LOS phase variant of strain 2336, was less extensively sialylated when the growth medium was supplemented with CMP-NeuAc or NeuAc, as determined by electrophoretic profiles and electrospray mass spectrometry. The sialyltransferase of H. somnus strain 738 was confirmed to preferentially sialylate the Gal(beta)-(1-3)-GlcNAc component of the lacto-N-tetraose structure by capillary electrophoresis assay. Enhanced sialylation of the strain 2336 LOS inhibited the binding of monoclonal antibodies to LOS by enzyme immunoassay and Western blotting. Furthermore, sialylation of the LOS enhanced the resistance of H. somnus to the bactericidal action of antiserum to LOS. Sialylation and increased resistance to killing by normal serum also occurred in a deletion mutant that was deficient in the terminal Gal-GlcNAc disaccharide. LOS sialylation may therefore be an important virulence mechanism to protect H. somnus against the host immune system.
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PMID:Incorporation of N-acetylneuraminic acid into Haemophilus somnus lipooligosaccharide (LOS): enhancement of resistance to serum and reduction of LOS antibody binding. 1218 31

Previous studies suggested that nontypeable Haemophilus influenzae (NTHI) can form biofilms during human and chinchilla middle ear infections. Microscopic analysis of a 5-day biofilm of NTHI strain 2019 grown in a continuous-flow chamber revealed that the biofilm had a diffuse matrix interlaced with multiple water channels. Our studies showed that biofilm production was significantly decreased when a chemically defined medium lacking N-acetylneuraminic acid (sialic acid) was used. Based on these observations, we examined mutations in seven NTHI strain 2019 genes involved in carbohydrate and lipooligosaccharide biosynthesis. NTHI strain 2019 with mutations in the genes encoding CMP-N-acetylneuraminic acid synthetase (siaB), one of the three NTHI sialyltransferases (siaA), and the undecaprenyl-phosphate alpha-N-acetylglucosaminyltransferase homolog (wecA) produced significantly smaller amounts of biofilm. NTHI strain 2019 with mutations in genes encoding phosphoglucomutase (pgm), UDP-galactose-4-epimerase, and two other NTHI sialyltransferases (lic3A and lsgB) produced biofilms that were equivalent to or larger than the biofilms produced by the parent strain. The biofilm formed by the NTHI strain 2019pgm mutant was studied with Maackia amurensis fluorescein isothiocyanate (FITC)-conjugated and Sambucus nigra tetramethyl rhodamine isocyanate (TRITC)-conjugated lectins. S. nigra TRITC-conjugated lectin bound to this biofilm, while M. amurensis FITC-conjugated lectin did not. S. nigra TRITC-conjugated lectin binding was inhibited by incubation with alpha2,6-neuraminyllactose and by pretreatment of the biofilm with Vibrio cholerae neuraminidase. Matrix-assisted laser desorption ionization-time of flight mass spectometry analysis of lipooligosaccharides isolated from a biofilm, the planktonic phase, and plate-grown organisms showed that the levels of most sialylated glycoforms were two- to fourfold greater when the lipooligosaccharide was derived from planktonic or biofilm organisms. Our data indicate that NTHI strain 2019 produces a biofilm containing alpha2,6-linked sialic acid and that the sialic acid content of the lipooligosaccharides increases concomitant with the transition of organisms to a biofilm form.
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PMID:Nontypeable Haemophilus influenzae strain 2019 produces a biofilm containing N-acetylneuraminic acid that may mimic sialylated O-linked glycans. 1521 70

The ability to bind extracellular matrix proteins is a critical virulence determinant for skin pathogens. Haemophilus ducreyi, the etiological agent of the genital ulcer disease chancroid, binds extracellular matrix components, including fibronectin (FN). We investigated H. ducreyi FN binding and report several important findings about this interaction. First, FN binding by H. ducreyi was greatly increased in bacteria grown on heme and almost completely inhibited by hemoglobin. Second, wild-type strain 35000HP bound significantly more FN than did a dsrA mutant in two different FN binding assays. Third, the expression of dsrA in the dsrA mutant restored FN binding and conferred the ability to bind FN to a non-FN-binding Haemophilus influenzae strain. Fourth, an anti-DsrA monoclonal antibody partially blocked FN binding by H. ducreyi. The hemoglobin receptor, the collagen-binding protein, the H. ducreyi lectin, the fine-tangle pili, and the outer membrane protein OmpA2 were not involved in H. ducreyi FN binding, since single mutants bound FN as well as the parent strain did. However, the major outer membrane protein may have a minor role in FN binding by H. ducreyi, since a double dsrA momp mutant bound less FN than did the single dsrA mutant. Finally, despite major sequence differences, DsrA proteins from both class I and class II H. ducreyi strains mediated FN and vitronectin binding. We concluded that DsrA is the major factor involved in FN binding by both classes of H. ducreyi strains.
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PMID:Outer membrane protein DsrA is the major fibronectin-binding determinant of Haemophilus ducreyi. 1821 73

Pathogenic microbes acquire human complement inhibitors to circumvent the innate immune system. In this study, we identify two novel host-pathogen interactions, factor H (FH) and factor H-like protein 1 (FHL-1), the inhibitors of the alternative pathway that binds to Hib. A collection of clinical Haemophilus influenzae isolates was tested and the majority of encapsulated and unencapsulated bound FH. The isolate Hib 541 with a particularly high FH-binding was selected for detailed analysis. An increased survival in normal human serum was observed with Hib 541 as compared with the low FH-binding Hib 568. Interestingly, two binding domains were identified within FH; one binding site common to both FH and FHL-1 was located in the N-terminal short consensus repeat domains 6-7, whereas the other, specific for FH, was located in the C-terminal short consensus repeat domains 18-20. Importantly, both FH and FHL-1, when bound to the surface of Hib 541, retained cofactor activity as determined by analysis of C3b degradation. Two H. influenzae outer membrane proteins of approximately 32 and 40 kDa were detected with radiolabeled FH in Far Western blot. Taken together, in addition to interactions with the classical, lectin, and terminal pathways, H. influenzae interferes with the alternative complement activation pathway by binding FH and FHL-1, and thereby reducing the complement-mediated bactericidal activity resulting in an increased survival. In contrast to incubation with active complement, H. influenzae had a reduced survival in FH-depleted human serum, thus demonstrating that FH mediates a protective role at the bacterial surface.
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PMID:Haemophilus influenzae interacts with the human complement inhibitor factor H. 1856 20


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