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PubMed2004

Study of humoral immunity to commensal oral bacteria in human infants demonstrates the presence of secretory immunoglobulin A antibodies reactive with Actinomyces naeslundii genospecies 1 and 2 ribotypes.

The mouths of three human infants were examined from birth to age 2 years to detect colonization of Actinomyces naeslundii genospecies 1 and 2. These bacteria did not colonize until after tooth eruption. The diversity of posteruption isolates was determined by ribotyping. Using immunoblotting and enzyme-linked immunosorbent assay, we determined the reactivity of secretory immunoglobulin A (SIgA) antibodies in saliva samples collected from each infant before and after colonization against cell wall proteins from their own A. naeslundii strains and carbohydrates from standard A. naeslundii genospecies 1 and 2 strains. A. naeslundii genospecies 1 and 2 carbohydrate-reactive SIgA antibodies were not detected in any saliva sample. However, SIgA antibodies reactive with cell wall proteins were present in saliva before these bacteria colonized the mouth. These antibodies could be almost completely removed by absorption with A. odontolyticus, a species known to colonize the human mouth shortly after birth. However, after colonization by A. naeslundii genospecies 1 and 2, specific antibodies were induced that could not be removed by absorption with A. odontolyticus. Cluster analysis of the patterns of reactivity of postcolonization salivary antibodies from each infant with antigens from their own strains showed that not only could these antibodies discriminate among strains but antibodies in saliva samples collected at different times showed different reactivity patterns. Overall, these data suggest that, although much of the salivary SIgA antibodies reactive with A. naeslundii genospecies 1 and 2 are directed against genus-specific or more broadly cross-reactive antigens, species, genospecies, and possibly strain-specific antibodies are induced in response to colonization.

Actinomyces↗
PubMed2006

Host-derived pentapeptide affecting adhesion, proliferation, and local pH in biofilm communities composed of Streptococcus and Actinomyces species.

Salivary proline-rich proteins (PRPs) attach commensal Actinomyces and Streptococcus species to teeth. Here, gel filtration, mass spectrometry and Edman degradation were applied to show the release of a pentapeptide, RGRPQ, from PRP-1 upon proteolysis by Streptococcus gordonii. Moreover, synthetic RGRPQ and derivatives were used to investigate associated innate properties and responsible motifs. The RGRPQ peptide increased 2.5-fold the growth rate of S. gordonii via a Q-dependent sequence motif and selectively stimulated oral colonization of this organism in a rat model in vivo. In contrast, the growth of Streptococcus mutans, implicated in caries, was not affected. While the entire RGRPQ sequence was required to block sucrose-induced pH-decrease by S. gordonii and S. mutans, the N-terminal Arg residue mediated the pH increase (i.e., ammonia production) by S. gordonii alone (which exhibits Arg catabolism to ammonia). Strains of commensal viridans streptococci exhibited PRP degradation and Arg catabolism, whereas cariogenic species did not. The RGRPQ peptide mediated via a differential Q-dependent sequence motif, adhesion inhibition, and desorption of PRP-1-binding strains of A. naeslundii genospecies 2 (5 of 10 strains) but not of S. gordonii (n=5). The inhibitable A. naeslundii strains alone displayed the same binding profile as S. gordonii to hybrid peptides terminating in RGRPQ or GQSPQ, derived from the middle or C-terminal segments of PRP-1. The present findings indicate the presence of a host-bacterium interaction in which a host peptide released by bacterial proteolysis affects key properties in biofilm formation.

Actinomyces↗
PubMed1974

Extracellular polysaccharides of Actinomyces viscosus.

Polysaccharide(s) have been isolated from supernatants of broth cultures of Actinomyces viscosus, strain T6. The organism produces significant quantities (2 mg/mg of cell [dry weight], 108 mg/liter) of this polysaccharide in the absence of sucrose. Chemical analysis indicated that N-acetylglucosamine (62%) was the major component; galactose (7%), glucose (4%), uronic acid (3%), and smaller amounts of glycerol, rhamnose, arabinose, and xylose were also present. The polysaccharide(s) is only slightly soluble in aqueous solutions. Although further purification of the polysaccharides will be necessary before definitive chemical and structural studies, the formation of extracellular polysaccharides is significant because it offers a possible explanation for plaque formation by these organisms.

Actinomyces↗
PubMed1975

Serological studies of Actinomyces israelii by crossed immunoelectrophoresis: taxonomic and diagnostic applications.

Crossed immunoelectrophoresis (CIE) with intermediate gel was applied to the serological analysis of Actinomyces israelii to develop a test with high efficiency in the laboratory diagnosis of human actinomycosis and classification of A. israelii. Recently developed standard antigen-antibody systems for A. israelii by CIE were used as reference. The reference systems were based on standard preparations of cytoplasmic and whole cell-associated antigens of A. israelii and a standard immunoglobulin G pool purified from rabbit antisera to formalin-treated whole cells and cell lysates of A. israelii. The specificity of the standard antigens for A. israelii was evaluated in CIE studies by screening for antibodies to components of the antigens in rabbit antisera raised against related bacteria. The standard system for A. israelii based on cytoplasmic antigens formed species-specific precipitins whereas antisera raised against A. naeslundii and/or Propionibacterium acnes precipitated components of the other standard antigens. As a result of these analyses, the standard system for A. israelii based on 10 cytoplasmic antigens was used as reference for CIE studies to detect humoral antibodies to A. israelii in sera from nine patients with actinomycosis. All the sera from the patients formed at the time of diagnosis one or more precipitins in terms of the 10 reference precipitins. Up to five precipitins were found in single sera. Follow-up studies covering a period of one-half year after treatment showed a gradually decreased precipitin response in the course of time. In control sera from patients with newly diagnosed tuberculosis, nocardiosis, deep Candida infection, and aspergillosis, and in sera from healthy blood donors, no antibodies were detected with specificity for the reference antigens.

Actinomyces↗
PubMed1975

Characterization of a dextranase produced by an oral strain of Actinomyces israelii.

A dextranase-producing, gram-positive, anaerobic, rod-shaped bacterium isolated from human dental plaque was identified as Actinomyces israeli. Although the extracellular dextranase (EC 3.2.1.11) formed by this microbe appeared to be constitutively produced, the bacterium did not utilize the reaction products as a carbon source during growth. A striking feature of the dextranase was the formation of two distinct groups of oligosaccharide end products. The two groups presumably correspond to the limit dextran and the released reaction product which appeared to be cleaved from the end(s) of larger dextran molecules. Low levels of dextranase activity were measured by [3H]NaBH4 reduction and alcohol fixation of the large, tritiated end products on filter paper disks. Of the carbohydrate substrates tested, only alpha-1,6-linked glucans were cleaved. The enzyme did not exhibit any metal ion requirements, and its pH optimum was 6.3. It is suggested that the A. israelii dextranase may function as a regulatory factor during extracellular in vivo glucan synthesis from sucrose by various plaque microbes.

Actinomyces↗
PubMed1976

Dextran-mediated interbacterial aggregation between dextran-synthesizing streptococci and Actinomyces viscosus.

Streptococcus sanguis and Streptococcus mutans bind to the surface of Actinomyces viscosus, producing large microbial aggregates. Aggregates form rapidly and are not easily dissociated by vigorous mixing. The binding is mediated by dextran. Glucose-grown streptococci will not aggregate unless they are first mixed with high-molecular-weight dextran. Aggregation is induced with dextrans isolated from Leuconostoc, S. sanguis, or S. mutans. Sucrose-grown streptococci will adhere to A. viscosus without the addition of an exogenous source of dextran. A. viscosus will bind dextran and then bind glucose-grown streptococci. Aggregation occurs over a wide pH range and is dependent on cations. The aggregating activity of A. viscosus is both protease and heat sensitive. The aggregating activity of S. sanguis is heat stable but sensitive to dextranase.

Actinomyces↗
PubMed1976

Cell-mediated immune response to products of Actinomyces viscosus cultures.

Hartley strain guinea pigs were sensitized with 0.5 ml of concentrated cell-free Actinomyces viscosus culture supernatant fluids mixed with Freund complete adjuvant. Fourteen to 16 days later the animals were challenged by intradermal injection with 0.1 ml of the culture supernatant, and the reactions were observed at 4, 8, 16, 24, and 48 h. Peritoneal exudate cells from sensitized animals were used for determination of migration inhibition factor, and guinea pig peripheral blood served as a source of cells for determining the induction of mitogenesis by antigenic material. Skin responses were consistently positive to challenge with the test material, whereas reactions to noninoculated culture medium were negative. Sensitized cells, challenged with antigen, resulted in 60% or greater inhibition of migration of indicator cells in migration inhibition factor experiments. Tests for mitogenesis showed a greater than fourfold increase in isotope uptake when sensitized cells were challenged with test material. The data are consistent with the suggestion that A. viscosus culture supernatants contain substances that induce cell-mediated immune responses in guinea pigs.

Actinomyces↗
PubMed1976

Interaction of inflammatory cells and oral microorganisms. III. Modulation of rabbit polymorphonuclear leukocyte hydrolase release response to Actinomyces viscosus and Streptococcus mutans by immunoglobulins and complement.

In the absence of antiserum, rabbit polymorphonuclear leukocytes (PMNs) released lysosomal enzymes in response to Actinomyces viscosus (19246) but not to Streptococcus mutans (6715). Antibodies had a marked modulating influence on these reactions. PMN hydrolase release was significantly enhanced to both organisms when specific rabbit antiserum and isolated immunoglobulin G (IgG) were included in the incubations. Immune complex F(ab')2 fragments of IgG directed against S. mutans agglutinated bacteria. Immune complexes consisting of S. mutans and F(ab')2 fragments of IgG directed against this organism were not effective as bacteria-IgG complexes in stimulating PMN release. The intensity of the release response to bacteria-IgG complexes was also diminished when PMNs were preincubated with isolated Fc fragments derived from IgG. Fresh serum as a source of complement components had no demonstrable effect on PMN release either alone or in conjuction with antiserum in these experiments. These data may be relevant to the mechanisms and consequences of the interaction of PMNs and plaque bacteria in the pathogenesis of periodontal disease.

Actinomyces↗
PubMed1977

Levan and levansucrase of Actinomyces viscosus.

A levansucrase was demonstrated in the growth medium and in association with the cell surface of Actinomyces viscosus. The amount of enzyme produced relative to cell density is not significantly affected by the growth conditions. Sugar alcohols inhibit growth of the cells. The levansucrase hydrolyzes sucrose to produce free glucose and levan; some free fructose is also formed. There is no requirement for cofactors. The Km for sucrose is 12 mM. A variety of heavy metal ions and two disaccharides, lactose and cellobiose, inhibit the enzyme. The levansucrase was purified to homogeneity and has a specific activity of 90 micronmol of glucose release per min per mg. The enzyme has a molecular weight of 220,000 and is composed of subunits of molecular weight 80,000. The levan product contains both beta(2 leads to 1) and beta(2 leads to 6) linkages. The enzyme remains tightly bound to the levan product, resulting in the formation of high-molecular-weight polymer on the order of 10(8) daltons. The possible role of the levan and levansucrase of A. viscosus in the pathogenesis of periodontal disease is discussed.

Actinomyces↗
PubMed1977

Identification, separation, and preliminary characterization of invertase and beta-galactosidase in Actinomyces viscosus.

The initial step of disaccharide dissimilation by Actinomyces viscosus serotype 2 strain M-100 was studied. Sucrase activity was found in the 3,000 X g particulate fraction and the 37,000 X g soluble fraction of the cells, whereas lactase activity was found almost exclusively in the 37,000 X g soluble fraction. Neither sucrase nor lactase activity was appreciable in the culture liquor. Sucrose phosphorylase, alpha-glucosidase, and polysaccharide synthesis activities were not observed in the soluble cell fraction. The sucrase was identified as invertase (EC 3.2.1.26; beta-D-fructofuranoside fructohydrolase). The lactase was identified as beta-galactosidase (EC 3.2.1.23; beta-D-galactoside galactohydrolase). The enzymes in the 37,000 X g soluble fraction were separable by diethylamino-ethyl-cellulose chromatography, giving one beta-galactosidase peak and one major and one minor invertase peak. Acrylamide gel electrophoresis showed different electrophoretic mobilities of the enzymes. The molecular weight of the beta-galactosidase is about 4.2 X 10(5) and that of invertase is about 8.6 X 10(4). The beta-galactosidase has a Km for lactose of about 6 mM and a pH optimum between pH 6.0 and 6.5. The major invertase component has a Km for sucrose of about 71 mM and a pH optimum between pH 5.8 and 6.3.

Actinomyces↗
PubMed1977

Regulation of invertase of Actinomyces viscosus.

The regulation of diethylaminoethyl-partially purified invertase (EC 3.2.1.26; beta-D-fructofuranoside fructohydrolase) from the 37,000 X g-soluble intracellular fluid of Actinomyces viscosus serotype 2 strain M-100 was studied. Glycolytic intermediates, mono-, di-, and triphosphate nucleotides, inorganic phosphate, and various divalent cations were tested for regulatory effects. Fructose-6-phosphate (F6P) and fructose-1,6-diphosphate (FDP) were found to act as noncompetitive inhibitors of invertase. The Ki values for F6P and FDP were found to be 3.4 and 5.1 mM, respectively. The Hill coefficient for sucrose was 1.03 and remained unchanged in the presence of varying amounts of F6P or FDP.

Actinomyces↗
PubMed1978

Morphological features and functional properties of human fibroblasts exposed to Actinomyces viscosus substances.

Connective tissue fibroblasts undergo cytopathic degenerative changes during certain long-term inflammatory diseases such as rheumatoid arthritis and periodontitis. The failure of inflamed tissues to repair properly may result from functional alterations of fibroblasts within the affected tissues. Numerous previous studies indicate that direct cytotoxicity by bacterial or other substances may be responsible for the cellular alterations observed in vivo. We have tested this hypothesis by exposing cultures of human diploid fibroblasts to homogenates of Actinomyces viscosus (a microorganism associated with periodontitis and capable of causing other chronic inflammatory diseases) and analyzing the effects on cell viability, morphology, and function. The cells bind and subsequently engulf relatively large quantities of the bacterial substances. These substances do not appear to be toxic to fibroblasts as determined by 51Cr release and microcytotoxicity assays, although there is a slight but significant decrease in protein synthesis (P less than 0.01) as measured by the incorporation of [14C]proline. However, collagen production was not altered, and the cytopathic alterations observed in diseased tissues in vivo did not occur in the exposed cells. These findings suggest that A. viscosus substances do not directly cause injury to connective tissue fibroblasts in periodontal disease but may, through cell-surface binding, mark these cells for subsequent immune-mediated damage.

Actinomyces↗
PubMed1978

Identification of the virulence-associated antigen on the surface fibrils of Actinomyces viscosus T14.

Actinomyces viscosus T14V is virulent (V) for monoinfected rats, causing periodontal disease and bone loss, whereas, A. viscosus T14AV, a mutant strain, is avirulent (AV). Surface antigens from the T14V and T14AV strains were prepared by lysozyme digestion of cell walls and were compared by immunodiffusion against antisera to T14V and T14AV whole cells. The V-associated antigen (V-antigen) was detected readily in the T14V, but not readily in the T14AV cell wall extract. Antiserum specific for the V-antigen was prepared by absorbing anti-A. viscosus T14V serum with cell walls from the T14AV strain. This antiserum was used in the indirect peroxidase-labeled antibody technique to localize the V-antigen on the bacterial cell surface at the ultrastructural level. With whole bacterial cells, the V-antigen was found on fine fibrils and was detected in both the T14V and T14AV strains. The presence of V-antigen on the AV strain was supported by the demonstration of antibodies against the V-antigen in anti-A. viscosus T14AV serum. Examination of isolated bacterial cell walls revealed a greater amount of fibrils and V-antigen on the T14V cell wall than on the T14AV cell wall. The data suggest that the presence of V-antigen represents a quantitative rather than a qualitative difference between the V and the AV strains of A. viscosus T14. Samples of human plaque were examined, and the V-antigen was found to be a specific marker for the fibril-containing layer of certain plaque bacteria, which are probably strains of A. viscosus or A. naeslundii.

Actinomyces↗
PubMed1978

Cell-associated levan of Actinomyces viscosus.

Actinomyces viscosus ATCC 15987 was examined for the presence of cell-associated levan by absorption of myeloma proteins with antilevan activity and direct immunofluorescence. Levan was not detectable on the surface of glucose-grown A. viscosus, but after a brief incubation of these cells with 5% sucrose, they were encapsulated with tenaciously adhering levan. The levan layer constituted between 0.02 and 0.03% of the cell dry weight. In contrast, sucrose-grown A. viscosus cells possessed a low level of cell-associated levan, which was only moderately increased by incubation in sucrose and which partially existed as a loose slime rather than a tenacious capsule.

Actinomyces↗
PubMed1978

Interaction of inflammatory cells and oral microorganisms. VII. In vitro polymorphonuclear responses to viable bacteria and to subcellular components of avirulent and virulent strains of Actinomyces viscosus.

Both virulent (V) and avirulent (AV) strains of Actinomyces viscosus T14 are capable of colonizing the oral cavity of gnotobiotic rats, but only T14-V causes destructive periodontal disease. The basis for this difference in in vivo pathogenicity has not been adequately defined. In the present study we compared the capacities of T14-AV and T14-V to provoke in vitro extracellular release of lysosomal constituents from human polymorphonuclear leukocytes (PMNs). In serum-free cultures, viable T14-V but not T14-AV stimulated discharge of PMN lysosomes. The release response was correlated with PMN phagocytic activity; thus, PMNs readily ingested T14-V but not T14-AV. To explain these differences in PMN-bacteria interactions, subcellular fractions of T14-AV or T14-V were incubated with PMNs. A crude, insoluble sonic extract derived from T14-V caused PMN lysosome release, but a similar fraction from T14-AV was inactive. However, following extensive washing and treatment with deoxyribonuclease or sodium dodecyl sulfate, cell wall fractions of T14-AV stimulated lysosome release. These procedures apparently removed an extracellular polysaccharide slime which is synthesized by T14-AV but not by T14-V. There was a significant reduction in the capacities of viable T14-V or cell wall fractions of T14-V or T14-AV to provoke PMN lysosome release when these agents were preincubated with a slime material isolated from T14-AV. This inhibitory influence of slime was overcome by the addition of fresh or heated (56 degrees C, 30 min) serum to the PMN-bacteria cultures. The data suggest a relationship between the abilities of the avirulent and virulent strains of A. viscosus T14 to act as periodontal pathogens in vivo and to serve as stimuli for PMN lysosome release in vitro.

Actinomyces↗
PubMed1978

Mechanism of coaggregation between Actinomyces viscosus T14V and Streptococcus sanguis 34.

Actinomyces viscosus T14V and Streptococcus sanguis 34 coaggregate by a mechanism which is not inhibited by 1 M NaCl, is dextran independent, requires calcium, is pH dependent with an optimum at pH 8.0 to 8.5, and appears to require the interaction of a protein or glycoprotein on A. viscosus with a carbohydrate on S. sanguis. The coaggregation is inhibited more than 80% by 0.01 M lactose, 0.02 M beta-methyl-D-galactoside, or 0.05 M D-galactose; inhibition of coaggregation was less than 10% in 0.1 M alpha-methyl-D-galactoside, melibiose, maltose, cellobiose, sucrose, and a number of monosaccharides. At very high concentrations of enzyme, protease from S. griseus destroyed the reactive site on A. viscosus but not on S. sanguis. Both were totally resistant to dextranase. Periodate (0.01 M; pH 4) inactivated both bacteria. The ability of S. sanguis to coaggregate with A. viscosus was not destroyed by phenol-water extraction at 65 degrees C for 15 min. When the bacteria were cultured under specified conditions, the coaggregation was highly reproducible. Under the same conditions, T14AV, the avirulent mutant of A. viscosus T14V, did not coaggregate with S. sanguis 34. Electron microscopic studies of coaggregates, labeled immunochemically with antibody to A. viscosus, indicated that fibrils on A. viscosus may be involved in the coaggregation.

Actinomyces↗
PubMed1978

Degradation of levan by Actinomyces viscosus.

Actinomyces viscosus ATCC 15987 was examined for its ability to hydrolyze its own levan. Washed whole cells and an ammonium sulfate fraction from cell-free culture fluids were shown to possess levan hydrolase activity. Analyses of reaction mixtures by gel filtration and thin-layer chromatography demonstrated that the product of levan hydrolysis was free fructose. The cell-associated and extracellular enzyme preparations also hydrolyzed inulin and the levans synthesized by Aerobacter levanicum and Bacillus subtilis. Growth of A. viscosus in media supplemented with 0.1% A. viscosus levan resulted in a 33-fold increase and a 7-fold increase in the specific activities of the respective extracellular and cell-associated enzymes when compared with those from 55 mM glucose cultures. Growth in the presence of 29.2 mM sucrose resulted in a 28-fold increase and a 5-fold increase in the specific activities of the respective enzymes when compared with those from the glucose cultures. The extracellular enzyme exhibited high activity over a wide pH range, with 87 and 89% of its pH 6.0 optimum activity at pH 5.0 and 7.0, respectively. The cell-associated enzyme also exhibited optimum activity at pH 6.0, but this was decreased to 10 and 20% at pH 5.0 and 7.0, respectively. Analysis for the presence of extracellular levan during growth of A. viscosus in sucrose broths demonstrated that peak levan concentrations occurred during the mid-exponential to late-exponential phase of growth followed by a rapid decline in extracellular levan as a result of levan hydrolase activity.

Actinomyces↗