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At least 451 records · Page 25Linked to original sources
PubMed1989

Formation of delta 2- and delta 3-cholenoic acids from bile acid 3-sulfates by a human intestinal Fusobacterium strain.

We isolated two strains of an unnamed Fusobacterium species from human intestinal microflora, which stereospecifically transformed bile acid 3-sulfates into C-3-unsubstituted, ring A-unsaturated bile acids. Both 3 alpha- and 3 beta-sulfates of 5 beta-bile acids were metabolized to delta 3-5 beta-cholenoic acids; 3 beta-sulfates of 5 alpha-bile acids were converted into a mixture of delta 2-5 alpha-bile acids and 3 alpha-hydroxy-5 alpha-bile acids, whereas 3 alpha-sulfates of 5 alpha-bile acids were left intact. Unsulfated bile acids were not transformed into unsaturated derivatives. These strains differ from previously isolated intestinal bacteria, which desulfated bile acid sulfates without further transformation.

Bile Acids and Salts↗
PubMed1994

Selective enumeration of Fusobacterium necrophorum from the bovine rumen.

A culture medium containing lactate as the sole energy source and antibiotics (bacitracin, gentamicin, and streptomycin) was used for selection and enumeration of Fusobacterium necrophorum from bovine ruminal contents. F. necrophorum growth was determined by indole production, and enumeration was performed by the most-probable-number technique. The number of F. necrophorum cells in cattle fed a 100% forage diet was 7 x 10(5)/g of ruminal contents. The number increased (P < 0.05) 10-fold after the diet was changed to 85% corn grain.

Animal Feed↗
PubMed2004

Characterization of the novel Fusobacterium nucleatum plasmid pKH9 and evidence of an addiction system.

Fusobacterium nucleatum is an important oral anaerobic pathogen involved in periodontal and systemic infections. Studies of the molecular mechanisms involved in fusobacterial virulence and adhesion have been limited by lack of systems for efficient genetic manipulation. Plasmids were isolated from eight strains of F. nucleatum. The smallest plasmid, pKH9 (4,975 bp), was characterized and used to create new vectors for fusobacterial genetic manipulation. DNA sequence analysis of pKH9 revealed an open reading frame (ORF) encoding a putative autonomous rolling circle replication protein (Rep), an ORF predicted to encode a protein homologous to members of the FtsK/SpoIIIE cell division-DNA segregation protein family, and an operon encoding a putative toxin-antitoxin plasmid addiction system (txf-axf). Deletion analysis localized the pKH9 replication region in a 0.96-kbp fragment. The pKH9 rep gene is not present in this fragment, suggesting that pKH9 can replicate in fusobacteria independently of the Rep protein. A pKH9-based, compact Escherichia coli-F. nucleatum shuttle plasmid was constructed and found to be compatible with a previously described pFN1-based fusobacterial shuttle plasmid. Deletion of the pKH9 putative addiction system (txf-axf) reduced plasmid stability in fusobacteria, indicating its addiction properties and suggesting it to be the first plasmid addiction system described for fusobacteria. pKH9, its genetic elements, and its shuttle plasmid derivatives can serve as useful tools for investigating fusobacterial properties important in biofilm ecology and pathogenesis.

Amino Acid Motifs↗
PubMed1975

Characterization of endotoxin from Fusobacterium necrophorun.

Endotoxic lipopolysachharide (LPS) was obtained from phenol-water extraction of cell walls prepared from mass-cultivated Fusobacterium necrophorum. The LPS was relatively free of nucleic acids and low in protein, and constituted about 4% of the cell walls. Upon acid hydrolysis, some of the components detected were hexosamines (7.0%), neutral and reducing sugars (50.5%), heptose (6.4%), 2-keto-3-deoxyoctonate (0.8%), lipid A (21.0%), and phosphorus (1.7%). Under electron microscopy the LPS appeared mainly as ribbon-like trilaminar structures, and upon chemical treatment it displayed a behavior resembling that reported in certain enterobacterial LPS. The LPS was lethal to mice, 11-day-old chicken embryos, and rabbits. Endotoxicity in mice was enhanced at least 1,380-fold by the addition of 12.5 mug of actinomycin D. Induced tolerance to lethal effect of the endotoxin and rapidly acquired resistance to infection by F. necrophrum viable cells were also demonstrated in mice. The endotoxin produced both localized and generalized Shwartzman reactions as well as biphasic pyrogenic responses in rabbits. These results firmly establish the presence of a classical endotoxin in F. necrophorum, thus providing strong support to our recent suggestion that cell wall-associated components may contribute significantly to the pathogenicity of F. necrophorum.

Animals↗
PubMed1975

Biological characterization of Fusobacterium necrophorum. Cell fractions in preparation for toxin and immunization studies.

Fusobacterium necrophorum isolated from bovine liver abscesses was grown in bulk at 37 C for 24 h under a strict anaerobic atmosphere. Harvested washed cells were disrupted ultrasonically and fractionated by differential centrifugation into the intracellular (cytoplasm) and cell wall fractions. Both intact cells and cell fractions induced generalized cytopathic effect on primary pig kidney cultures and caused a variety of signs of illness and/or death of intraperitoneally injected mice. The intact cells, disrupted cells, and cell walls produced necrotic lesions and erythema on intradermally injected guinea pigs and rabbits, whereas the cytoplasm mainly erythema. By contrast, the used culture medium (culture filtrate) of F. necrophorum did not show any detectable toxicity. The toxic component of the cytoplasm appears to be associated with nondialyzable, hemolytic, high-molecular-weight proteins and its toxicity is reduced by trypsin and pronase. Heating at 60 C for 10 min decreased markedly its erythemal and cytotoxic ability, wheras the toxicity of the cell walls appeared to be only slightly affected even when heated at 100 C for 1 h. These results suggest that at leasttwo distinct cell-bound toxic factors are present in F. necrophorum cells.

Amino Acids↗
PubMed1976

Fusobacterium necrophorum infection in mice as a model for the study of liver abscess formation and induction of immunity.

A mouse model is described in which intraperitoneal injection of Fusobacterium necrophorum results in chronic liver abscesses. Viable bacterial counts from mouse lung, liver, and spleen were obtained after whole organ homogenization. From 2 h to 5 days postchallenge, liver was found to contain more bacteria than lung on a per gram basis. Bacterial counts from liver and spleen were about the same during the first 8 h; thereafter liver was found to contain more bacteria. By day 13, though bacterial counts were equivalent in the three organs, abscesses were only observed in liver. This predilection for the liver may be due to a nutritional and/or microenvironmental factor(s). Blood cultures of infected mice revealed a general lack of bacteremia. Extended immunization with formalin-killed cells was found to protect mice against F. necrophorum infection.

Animals↗
PubMed1977

Anticomplementary activity of Fusobacterium polymorphum in normal and C4-deficient sources of guinea pig complement.

Fusobacterium polymorphum has been isolated from the gingival crevice in humans and has been implicated in the immunopathology of periodontal diseases. The presence of alternative complement pathway factors in gingival crevice material suggests the contribution of this process in the manifestation of the local host response. A complement consumption assay was used to show that the anticomplementary activity of a cell-wall preparation from F. polymorphum in guinea pig complement progressed optimally at 37 degrees C and suboptimally at 0 degrees C. Similar levels of complement consumption were recorded at both temperatures, but a higher concentration of cell walls was required to demonstrate maximum activity in the cold. Augmentation experiments with additional normal and heat-treated complement showed the presence of heat-labile factors that controlled and limited the consumption of complement to a constant proportion of the total amount present. These same experiments indicated that there were no reactive antibodies in the complement used in the assay. Similar tests with C4-deficient guinea pig sera confirmed that F. polymorphum cell walls were capable of generating alternative complement pathway activity in guinea pig sera.

Cell Wall↗
PubMed1978

Immunoelectron microscopic localization of lipopolysaccharides in the cell wall of Bacteroides oralis and Fusobacterium nucleatum.

Lipopolysaccharides (LPS) have been extracted and purified from two anaerobic gram-negative bacteria: Bacteroides oralis and tfusobacterium nucleatum. Chemical analysis of the preparations showed a great proportion of neutral sugars, mainly glucose, in LPS of B. oralis. In rabbits, LPS of B. oralis induced both immunoglobulin M and G antibodies in contrast to LPS of F. nucleatum, to which only immunoglobulin M antibodies were produced. An immunohistochemical method with horseradish peroxidase-labeled antibodies was used to localize LPS antigens at the ultrastructural level. An electron-dense reaction product, representing an immune complex consisting of bacterial surface antigens and specific rabbit immunoglobulin labeled with peroxidase, was surrounding the cell wall, whereas appropriate controls were negative. The findings of the present study show that LPS of Bacteroides are probably bound to a complex, including glucans, in the outer membrane of the cell wall. LPS of Fusobacterium resemble LPS of other gram-negative bacteria.

Antigens, Bacterial↗
PubMed1979

Demonstration of lanthionine as a natural constituent of the peptidoglycan of Fusobacterium nucleatum.

Peptidoglycan was purified from the oral bacterium Fusobacterium nucleatum strain Fev 1, using boiling sodium dodecyl sulfate and pronase. The composition of this peptidoglycan was found to be similar to that of other gram-negative bacteria, except that it lacked diaminopimelic acid. Lanthionine, the monosulfur analog of diaminopimelic acid, was identified as the diaminodicarboxylic acid of this peptidoglycan. It is assumed that lanthionine replaced diaminopimelic acid. Thus, the peptidoglycan of F. nucleatum Fev 1 is one of the few known sources of naturally occurring lanthionine.

Alanine↗
PubMed1979

Human complement activation by lipopolysaccharides from bacteroides oralis, fusobacterium nucleatum, and veillonella parvula.

The properties of different lipopolysaccharide (LPS) preparations to induce C3 conversion in human serum was studied by means of crossed immunoelectrophoresis. C3 conversion by the alternative pathway was evaluated after calcium depletion, and lipid A-dependent activation was measured by means of inhibition with polymyxin B sulfate. LPS from Bacteroides oralis converted Co mainly via the alternative pathway, whereas LPS from Fusobacterium nucleatum and Veillonella parvula const pronounced lipid A-dependent conversion. The results are discussed in relation to the chemical composition of the LPS preparations.

Adult↗
PubMed1983

Corncob formation between Fusobacterium nucleatum and Streptococcus sanguis.

Corncob formation in dental plaque was believed to be limited to strains of Bacterionema matruchotii and Streptococcus sanguis. We observed recently that strains of Fusobacterium nucleatum also interacted with S. sanguis to form corncobs. Since the fusobacteria are among the first anaerobic filaments to colonize subgingival plaque, these interactions could serve as a connecting link between the transformation of supra- to subgingival plaque. To further characterize these interactions, quantitative in vitro studies of the kinetics of corncob formation of the fusobacteria were undertaken. These studies indicated that fewer streptococci were needed to saturate F. nucleatum strain 364 compared to strain 10953. Corncob formation with both strains was enhanced with increasing pH up to pH 8, at which point autoaggregation of the streptococci occurred. Variation in ionic strength and divalent cations had little effect on the interaction, and EDTA suppressed aggregate formation only slightly. Detergents at concentrations above 0.05% also inhibited corncob formation. Electron micrographs suggested that attachment of the cocci to the fusiforms was mediated through localized tufts of fimbriae, as they are in the Bacterionema system. However, although both trypsin and heat treatment of the streptococci inhibited corncob formation with fusobacteria, the effects were not as complete as those seen in Bacterionema species. Unlike the Bacterionema model, trypsin and heat treatment of the fusobacteria resulted in inhibition of corncob formation. These results suggest that several different receptors may be involved in corncob formation.

Adhesiveness↗
PubMed1983

Polyclonal activation of human peripheral blood B lymphocytes by Fusobacterium nucleatum.

The present study examined in vitro polyclonal human B-lymphocyte (B-cell) activation (PBA) by Fusobacterium nucleatum. Pokeweed mitogen, a well-studied PBA activator, was included in some experiments for comparison. PBA was determined by the total immunoglobulin A, G, and M concentrations in the culture supernatants as measured by micro-enzyme-linked immunosorbent assay. F. nucleatum, at concentrations between 1 and 10 micrograms/ml, stimulated optimal PBA in monocyte-depleted cultures, whereas the pokeweed mitogen response was optimal in unfractionated, monocyte-containing cultures. Immunoglobulin synthesis occurred primarily between days 6 and 8 after stimulation with F. nucleatum. T lymphocytes enhanced the PBA response to F. nucleatum, particularly at a T- to B-cell ratio of 1:1. Immunoglobulin production was greater in round-bottomed wells than in flat-bottomed wells at lymphocyte concentrations of 200,000 cells per well. The PBA response, however, increased dramatically in flat-bottomed wells containing higher lymphocyte concentrations, suggesting that PBA is enhanced by cell-to-cell contact. A delay in stimulation of the lymphocytes with F. nucleatum resulted in diminished immunoglobulin production. The results provide information on the regulation of in vitro PBA induced by F. nucleatum. The data also suggest that there may be differences in the mechanisms by which F. nucleatum and pokeweed mitogen stimulate PBA.

Adult↗
PubMed1983

Nonspecific induction of immunoglobulin M antibodies to periodontal disease-associated microorganisms after polyclonal human B-lymphocyte activation by Fusobacterium nucleatum.

The production of antibodies to oral bacteria was determined in lymphocyte cultures stimulated with sonicated Fusobacterium nucleatum, a potent inducer of polyclonal B-cell activation. After 9 days the cultures were examined by a microenzyme-linked immunosorbent assay for immunoglobulin M (IgM) antibodies to F. nucleatum, Bacteroides gingivalis, Actinomyces viscosus, and Streptococcus sanguis. Antibodies to these four bacteria were detected in cultures stimulated with polyclonal B-cell activation-inducing concentrations of F. nucleatum. However, significant concentrations of antibodies to F. nucleatum, but not to the other three microorganisms, were produced in cultures that received suboptimal polyclonal B-cell activation-inducing doses of F. nucleatum. Absorption studies indicated the specificity of the antibodies to each of the bacteria tested. IgM antibody production induced by F. nucleatum was enhanced by the addition of T cells. The production of IgM antibodies to the bacteria was reproducible in cultures from a single person tested on 3 consecutive days. The concentration of antibodies in replicate cultures, however, fluctuated greatly. To obtain consistent responses on successive days, multiple replicate cultures were required. These results suggest that F. nucleatum, which is frequently present in subgingival plaque, could induce the production of antibodies not only to F. nucleatum, but also to other microorganisms associated with periodontal diseases.

Antibody Specificity↗
PubMed1984

Isolation of a major cell envelope protein from Fusobacterium nucleatum.

A major, heat-modifiable cell envelope protein was identified in Fusobacterium nucleatum FDC 364 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein, designated HM-1, had apparent molecular weights of 38,500 and 50,000 when heated in sodium dodecyl sulfate at 50 and 100 degrees C, respectively. Whole cells were labeled with 125I, and the results suggested that the HM-1 protein may be exposed on the bacterial surface. The HM-1 protein was isolated in association with the peptidoglycan by extraction of whole cells or cell envelopes with 2% sodium dodecyl sulfate at 55 degrees C. Heating the peptidoglycan-HM-1 protein complex in the detergent at 100 degrees C resulted in the quantitative release of the protein. Isoelectric focusing experiments and amino acid analysis revealed that the HM-1 protein had a basic character and was moderately hydrophilic. Various strains of F. nucleatum as well as three oral fusiform isolates contained a serologically related protein. The abundance and location of the HM-1 protein in F. nucleatum suggest that it has the potential to participate in cell surface-related interactions of this bacterium.

Amino Acids↗
PubMed1986

Sensitization with Fusobacterium nucleatum targets antibody-dependent cellular cytotoxicity to mammalian cells.

Incubation of mammalian tumor cells with either soluble of insoluble fractions (10 to 100 micrograms/ml) of Fusobacterium nucleatum sensitizes them to the destructive activity of antibody-dependent cellular cytotoxicity (ADCC) effector cells in the presence of anti-F. nucleatum antisera. All three types of ADCC effector cells are capable of destroying F. nucleatum-sensitized target cells with varying degrees of effectiveness (lymphocytes much greater than monocytes greater than neutrophils). Hyperimmune rabbit anti-F. nucleatum antisera were active at a dilution as high as 1/100,000. Our studies indicated that F. nucleatum must be bound to the target cells since if either the effector cells are treated with F. nucleatum or F. nucleatum is directly to an ADCC reaction, there is no significant effect on cytotoxicity. The kinetics of F. nucleatum-targeted ADCC are identical to those of classical ADCC, suggesting a similar mechanism. The specificity of F. nucleatum-targeted ADCC was demonstrated by cold target inhibition studies and by showing that other antibacterial antisera were incapable of mediating the activity.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1988

Immunobiological activities of a porin fraction isolated from Fusobacterium nucleatum ATCC 10953.

From Fusobacterium nucleatum ATCC 10953 cell envelope fraction whose inner membranes had been removed by treatment with sodium N-lauroyl sarcosinate, an outer membrane protein (37,000 Mr in a native state) was prepared by extraction with lithium dodecyl sulfate. The protein thus obtained showed distinct porin activity, namely, the ability to form hydrophilic diffusion pores by incorporation into the artificial liposome membrane. The porin fraction exhibited strong immunobiological activities in the in vitro assays: B-cell mitogenicity and polyclonal B-cell activation on murine splenocytes, stimulatory effects on guinea pig peritoneal macrophages, and enhancement of the migration of human blood monocytes. The porin fraction also exhibited immunoadjuvant activity to increase the antibody production against sheep erythrocytes in the spleen of mice that were immunized by sheep erythrocytes with porin. Although chemical analyses revealed that the test porin fraction contained a considerable amount of lipopolysaccharide (LPS) (around 12% of the fraction), the studies with LPS-nonresponding C3H/HeJ mice and on the inhibitory effects of polymyxin B strongly suggest that most of the above bioactivities are due to porin protein itself, not to coexistent LPS in the porin fraction.

Adjuvants, Immunologic↗
PubMed1988

Identification of a galactose-binding lectin on Fusobacterium nucleatum FN-2.

A previous study has suggested that Fusobacterium nucleatum FN-2 contains a galactose-binding protein (lectin) on the cell surface (P. A. Murray, V. Matarese, C. I. Hoover, and J. R. Winkler, FEMS Microbiol. Lett. 40:123-127, 1987). In the present study, the molecular specificity and size of this lectin were investigated by several techniques. Whole-cell affinity chromatography with asialofetuin covalently coupled to Sepharose 6MB demonstrated that 81% of 3H-labeled F. nucleatum were specifically eluted by 0.5 M galactose. Specific binding was calcium dependent and did not occur in the presence of calcium chelators. Binding was inhibited by preincubation with galactose. Agglutination of human parotid saliva by F. nucleatum was also inhibited by galactose and its structural analogs. Inhibition by lactose was 2 times that of galactose, inhibition by p-aminophenyl galactosides was 4 times that of galactose, and inhibition by asialoglycopeptides was 100 times that of galactose. Similar inhibition results were obtained for hemagglutination of neuraminidase-treated erythrocytes. These findings suggest that the binding specificity of F. nucleatum FN-2 is more complex than simply the recognition of the monosaccharide galactose. This is consistent with the concept that lectins considered identical in terms of monosaccharide specificity can recognize fine differences in more complex structures. To identify the specific bacterial component(s) involved in galactose recognition, proteins of F. nucleatum FN-2 were separated on a 4 to 11% gradient sodium dodecyl sulfate slab gel, transferred to nitrocellulose paper to renature bacterial binding sites, and then incubated with 125I-labeled asialofetuin. Autoradiographs of the nitrocellulose revealed a band at a range of Mr 300,000 to 330,000 which was not present when the blots were preincubated with galactose. These data support the concept that F. nucleatum FN-2 possesses a lectin that recognizes galactose and galactose-containing substrates.

Asialoglycoproteins↗