Browsing by Subject "Moraxella catarrhalis"

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Open Access
Asialo-GM1 and asialo-GM2 are putative adhesion molecules for Moraxella catarrhalis
(Springer-Verlag, 2002) Ahmed, K.; Suzuki, Y.; Miyamoto, D.; Nagatake, T.
Moraxella catarrhalis is an important pathogen of respiratory and middle ear infections. We previously reported that the attachment of M. catarrhalis to pharyngeal epithelial cells is mediated by ganglioside M2 (GM2). Several sets of adhesins or receptors are involved in such attachment process. In this study, we used the same strains and similar bacterial culture conditions as those in our previous study, and demonstrated by thin layer chromatography that M. catarrhalis can also bind toasialo-GM1 (Gg4Cer) and asialo-GM2 (Gg3Cer). GalNAcβ1→4Galβ1 is a common sequence in both Gg4Cer and Gg3Cer, and in many respiratory bacteria, this sequence acts as a receptor for attachment to host cells. Treatment of human pharyngeal epithelial cells with anti-GM2 and anti-Gg4Cer antibodies significantlydecreased attachment of M. catarrhalis to these cells; however, treatment with anti-Gg3Cer antibody did not decrease M. catarrhalis attachment. Immunofluorescence microscopy revealed that human pharyngeal epithelial cells are positive for GM2 and Gg4Cer, but not for Gg3Cer. Our results indicate that Gg4Cer on human pharyngeal epithelial cells, and Gg3Cer, possibly on other cells, could serve as molecules for attachment of M. catarrhalis.
Open Access
Evidence for a novel bacteriophage from moraxella catarrhalis
(2005) Çakan, Gülçin
Moraxella catarrhalis is one of the major causes of RTI and otitis media, which was known as a harmless inhabitant of upper respiratory tract until 1980s. The knowledge on virulence factors, pathogenesis of this bacterium is scarce and the reason/(s) for recent pathogenic conversion of M. catarrhalis is/are not known. Several examples demonstrate that bacteriophages control bacterial virulence in almost every step of pathogenesis. Number of bacteriophages are known to be solely responsible from bacterial virulence. We hypothesize that a bacteriophage may be responsible for pathogenic conversion of M. catarrhalis, and we investigated whether a bacteriophage is present in M. catarrhalis. In this study, evidence for a bacteriophage from M.catarrhalis is presented. Supernatants of M.catarrhalis broth cultures were shown to cause bacterial cell lysis on soft agar cultures, indicating presence of bacteriophages released from them. Two particles having different morphologies and different size ranges (p<0. 05) were co-purified from these supernatants. One segment of dsDNA molecule and three segments of ssRNA molecules were extracted from these particles. The comparison between pathogenic and non-pathogenic strains of M.catarrhalis demonstrated marked differences in the quantity of these RNA and DNA molecules.Future studies are necessary to determine the origins of RNA and DNA molecules.
Open Access
Isolation and characterization of an adhesin protein from the surface of a respiratory pathogen Moraxella catarrhalis
(2002) Turan, Tolga
Moraxella catarrhalis is a member of the normal flora of upper respiratory tract. Starting in the early 1980s it gained importance as an important cause of otitis media in children and lower respiratory tract infections in adults with chronic obstructive pulmonary disease. β-lactamase producing strains of M. catarrhalis has been increasing at a very fast rate. In some locations, 100% of the strains are β- lactamase producer. The pathogenesis of infection by this bacterium is not clearly understood which hindered the development of a vaccine. In this study, a surface protein of about 55 kDa was isolated from M. catarrhalis by celite chromatography. It is a heat stable protein and is not affected by 2-mercaptoethanol or dithiothreitol treatment. The immunogenic property of the protein has been determined by immunizing rabbits with M. catarrhalis and detecting the antibody response in serum against 55 kDa protein by Western blotting. In addition, the protein is immunogenic in humans as antibody against 55 kDa protein can be detected in the sputum of patients with M. catarrhalis infection. Moreover, we determined upto 40 amino acids at the N-terminal and also two fragments of the protein. To determine the function of the protein, attachment inhibition assays were performed and it was found that 55 kDa protein competetively inhibits attachment of M. catarrhalis to human pharyngeal epithelial cells (HPEC). Similarly, monoclonal antibody against 55 kDa (mAb) blocks the protein and inhibits the attachment of M. catarrhalis to HPEC. These two lines of evidence show that 55 kDa protein is an adhesin of M. catarrhalis which mediate attachment to HPEC. In addition, immunoflourescence experiments further verified that 55 kDa protein binds to HPEC. To sequence the gene encoding 55 kDa protein, PCR was done using degenerate primers constructed from the Nterminal amino acid sequence. PCR amplification of the possible gene of 55 kDa protein resulted in a 500 bp fragment, but no homology can be obtained with Nterminal amino acid sequence. In addition, a genomic library of M. catarrhalis is prepared and screened with mAb and with a radiolabelled oligonucleotide probe. We isolated several positive clones; therefore in future it might be possible to sequence the gene encoding 55 kDa protein from these clones.
Open Access
Molecular characterization of the ATPase component of a putative ABC type transporter in moraxella catarrhalis
(2004) Şahin, Jale
Moraxella catarrhalis is one of the major causes of respiratory tract and middle ear infections. Little is known about the pathogenesis of M. catarrhalis infection. A pathogenic bacterium requires adherence, invasion, establishment and dissemination with the host for a successful infection. The interaction between the host and the pathogen also includes uptake and secretion of substances that are facilitated by a family of proteins termed transporters. ATP-binding cassette (ABC) transporter is one of the active transport system common in prokaryotic and eukaryotic cells. In this study, we identified a gene encoding ATPase component of the ABC type transporter in M. catarrhalis and performed a nucleotide and deduced amino acid sequence analysis of this gene. We used Genomic Survey Sequence approach (GSS) to identify the gene from M. catarrhalis genomic library. The insert size of the positive clone is 934 bp and was sequenced by DNA walking. The ATPase domain of an ABC type transporter has conserved motifs: Walker A, Q loop, C loop (signature sequence), Walker B, D loop and Switch II. The ATPase domain is considered as the most conserved domain of the ABC type transporter due to presence of these motifs. Based on the homology and motif search, and amino acid sequence alignment, performed by using BLAST programs available on the internet, it was found that the deduced amino acid sequence encoded by this gene exhibited 50-80% identity with the sequences of the ATPase component of the ABC transporters of several pathogens.
Open Access
Role of lipooligosaccharide in the attachment of Moraxella catarrhalis to human pharyngeal epithelial cells
(Wiley, 2005) Akgul, G.; Erturk, A.; Turkoz, M.; Turan, T.; Ichinose, A.; Nagatake, T.; Ahmed, K.
The goal of this study was to determine the role of lipooligosaccharide in the attachment of Moraxella catarrhalis to human pharyngeal epithelial cells. Strain 2951 and its Pk mutant strain 2951 galE were used in this study. This study suggests that the Pk epitope of LOS is not an adhesin for M. catarrhalis, but plays a crucial role by its surface charge in the initial stage of attachment.
Open Access
Sulfatide and its synthetic analogues recognition by Moraxella catarrhalis
(Springer, 2006) Ozcelik, P.; Bezirci, F. B.; Suzuki, Y.; Uzawa, H.; Nishida, Y.; Kobayashi, K.; Suzuki, T.; Miyamoto, D.; Nagatake, T.; Ahmed, K.
Moraxella catarrhalis is one of the major pathogens of respiratory and middle ear infections. Attachment of this bacterium to the surface of human pharyngeal epithelial cells is the first step in the pathogenesis of infections. This study revealed that sulfatide might act as a binding molecule for the attachment of M. catarrhalis to human pharyngeal epithelial cells. Furthermore, six different synthetic sulfatides were found to inhibit the attachment of M. catarrhalis significantly at an optimum concentration of 10 μg/ml. Synthetic sulfatides may have the potential to be used as a therapy to prevent M. catarrhalis infections.