| 1. |
- Ahrén, Irini Lazou, et al.
(författare)
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The importance of a β-glucan receptor in the nonopsonic entry of nontypeable Haemophilus influenzae into human monocytic and epithelial cells
- 2001
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 184:2, s. 150-158
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Tidskriftsartikel (refereegranskat)abstract
- Previous reports showed that nontypeable Haemophilus influenzae (NTHi) reside in macrophage-like cells in human adenoid tissue. This study investigated the ability of nonopsonized NTHi and encapsulated H. influenzae type b (Hib) to enter human monocytic and epithelial cells. The number of intracellular bacteria was determined by a viability assay and flow cytometry. To characterize the mechanisms responsible for the internalization of NTHi, different inhibitors of surface molecules, receptor turnover, and the cytoskeleton were used. Hib were found in monocytic cells at very low numbers (<100 bacteria/2 × 105 cells). In contrast, a great variation in intracellular numbers was detected between the different NTHi isolates (range, 0.0007%-0.28% of the inoculum for monocytes and 0.053%-3.5% for epithelial cells). NTHi entered human monocytic and epithelial cells via a receptor-mediated endocytosis involving mainly a β-glucan receptor that could be blocked by laminarin.
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| 2. |
- Janson, Håkan, et al.
(författare)
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Protein D, the immunoglobulin D-binding protein of Haemophilus influenzae, is a lipoprotein
- 1992
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Ingår i: Infection and Immunity. - 1098-5522. ; 60:4, s. 1336-1342
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Tidskriftsartikel (refereegranskat)abstract
- Protein D is an immunoglobulin D-binding membrane protein exposed on the surface of the gram-negative bacterium Haemophilus influenzae. Results reported here indicate that protein D is a lipoprotein. The protein is apparently synthesized as a precursor with an 18-residue-long signal sequence modified by the covalent attachment of both ester-linked and amide-linked palmitate to the cysteine residue, which becomes the amino terminus after cleavage of the signal sequence. Globomycin inhibited maturation of protein D in H. influenzae, implying that protein D is exported through the lipoprotein export pathway. A mutant expressing a protein D lacking the cysteine residue was constructed by oligonucleotide site-directed mutagenesis. The mutated protein D molecule was not acylated and partitioned in the aqueous phase after Triton X-114 extraction of intact bacteria, unlike native and recombinant protein D, which partitioned in the detergent phase. The nonacylated protein D molecule was localized to the periplasmic space of Escherichia coli. The hydrophilic protein D molecule will be used in investigations concerning its ability to function as a vaccine component.
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| 3. |
- Samuelsson, Martin, et al.
(författare)
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The IgD C(H)1 region contains the binding site for the human respiratory pathogen Moraxella catarrhalis IgD-binding protein MID.
- 2006
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Ingår i: European Journal of Immunology. - : Wiley. - 1521-4141 .- 0014-2980. ; 9:Sep;36, s. 2525-2534
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Tidskriftsartikel (refereegranskat)abstract
- The Moraxella catarrhalis IgD-binding protein (MID) has a unique specificity for human IgD, and the sequence with maximal IgD binding is located within the amino acids MID962-1200. In the present paper, we examined the MID binding site on IgD using a series of recombinant Ig. Full-length IgD, IgD F(ab')(2), and an IgD F(ab') C290R mutant lacking the inter-heavy-chain cysteine 290 were manufactured. Furthermore, a series of IgD/IgG chimeras were constructed. ELISA, dot blot and flow cytometry were used to study the binding of purified Ig to native MID, recombinant MID912-1200 or to Moraxella with or without MID. MID962-1200 bound both the IgD F(ab')(2) and F(ab') C290R, indicating that the binding occurred independently of antibody structure. When amino acids 157-224 of the IgD C(H)1 region were substituted with IgG sequences, binding by M. catarrhalis or recombinant MID962-1200 was abolished. Subsequent smaller substitutions of IgD C(H)1 157-224 with IgG sequences led us to conclude that IgD C(H)1 amino acids 198-206 were crucial for the interaction between MID and IgD.
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