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PubMed1998

Identification of two glycosylated components of Mycoplasma penetrans: a surface-exposed capsular polysaccharide and a glycolipid fraction.

Among the wall-less mycoplasmas only a few species have been identified with a capsule at their cell surface. Mycoplasma penetrans is a recently identified mycoplasma with unique morphology, isolated from HIV-infected patients. Using transmission electron microscopy, it was found that M. penetrans is surrounded by capsular material 11 nm (strain GTU-54-6A1) to 30 nm (strain HF-2) thick, which can be stained with ruthenium red and labelled with cationized ferritin. The polysaccharide composition of this capsule was indicated by its staining with periodic acid-thiocarbohydrazide silver proteinate and the abolition of ruthenium red staining of the cell surface by neuraminidase treatment. In addition, proteinase K treatment of the M. penetrans cells resulted in removal of the capsule, suggesting that polypeptides may contribute in anchoring it to the membrane or in its stability. Two different types of glycosylated material were detected in mycoplasma extracts by SDS-PAGE and periodic acid-Schiff staining. The first component was a high-molecular-mass material, which was heat- and proteinase-K-labile and which probably constitutes the capsular polymer. The other component was a low-molecular-mass glycolipid fraction, which was proteinase-K-, heat- and EDTA-resistant. The identification of a capsule at the M. penetrans cell surface is of particular interest for a mycoplasma which has been shown to adhere to various host cells and to penetrate into their intracellular compartments. The capsule may have significance in the pathogenesis of disease associated with infection by this organism.

Bacterial Capsules↗

PubMed2006

Ultrastructure and gliding motility of Mycoplasma amphoriforme, a possible human respiratory pathogen.

Despite their small size and reduced genomes, many mycoplasma cells have complex structures involved in virulence. Mycoplasma pneumoniae has served as a model for the study of virulence factors of a variety of mycoplasma species that cause disease in humans and animals. These cells feature an attachment organelle, which mediates cytadherence and gliding motility and is required for virulence. An essential component of the architecture of the attachment organelle is an internal detergent-insoluble structure, the electron-dense core. Little information is known regarding its underlying mechanisms. Mycoplasma amphoriforme, a close relative of both M. pneumoniae and the avian pathogen Mycoplasma gallisepticum, is a recently discovered organism associated with chronic bronchitis in immunosuppressed individuals. This work describes both the ultrastructure of M. amphoriforme strain A39(T) as visualized by scanning electron microscopy and the gliding motility characteristics of this organism on glass. Though externally resembling M. gallisepticum, M. amphoriforme cells were found to have a Triton X-100-insoluble structure similar to the M. pneumoniae electron-dense core but with different dimensions. M. amphoriforme also exhibited gliding motility using time-lapse microcinematography; its movement was slower than that of either M. pneumoniae or M. gallisepticum.

Humans↗

PubMed2004

The complete genome and proteome of Mycoplasma mobile.

Although often considered "minimal" organisms, mycoplasmas show a wide range of diversity with respect to host environment, phenotypic traits, and pathogenicity. Here we report the complete genomic sequence and proteogenomic map for the piscine mycoplasma Mycoplasma mobile, noted for its robust gliding motility. For the first time, proteomic data are used in the primary annotation of a new genome, providing validation of expression for many of the predicted proteins. Several novel features were discovered including a long repeating unit of DNA of approximately 2435 bp present in five complete copies that are shown to code for nearly identical yet uniquely expressed proteins. M. mobile has among the lowest DNA GC contents (24.9%) and most reduced set of tRNAs of any organism yet reported (28). Numerous instances of tandem duplication as well as lateral gene transfer are evident in the genome. The multiple available complete genome sequences for other motile and immotile mycoplasmas enabled us to use comparative genomic and phylogenetic methods to suggest several candidate genes that might be involved in motility. The results of these analyses leave open the possibility that gliding motility might have arisen independently more than once in the mycoplasma lineage.

Amino Acid Sequence↗

PubMed1981

Behavior of Mycoplasma hominis in a human diploid cell culture system.

The behavior of Mycoplasma hominis in normal human embryonic lung fibroblast (HAIN-55) cell cultures was investigated. Multiplication patterns of cell-associated mycoplasmas and of extracellular mycoplasmas in the HAIN-55 cultures depended upon the size of the inoculum. This relationship did not vary with the number of days the cells had been cultured, nor with the number of HAIN-55 cell passages. The maximum mycoplasmal growth was obtained with inoculum sizes of 10(5) to 10(6) colony-forming units (CFU)/ml. The recovery of mycoplasmas decreased rapidly with inoculum size beyond 10(7) CFU/ml, and growth of the HAIN-55 cells was inhibited. Growth of the cells was also inhibited by the addition of the cytoplasmic fraction of Mycoplasma hominis.

Cell Line↗

PubMed1988

Reiterated DNA sequences defining genomic diversity within the species Mycoplasma hyorhinis.

Genomic restriction fragments isolated from Mycoplasma hyorhinis and Mycoplasma hyopneumoniae were shown by DNA hybridization and nucleotide sequence analyses to contain sequences common to these two species, as well as another porcine-derived mycoplasma, Mycoplasma flocculare. Intraspecies hybridization experiments using these fragments as probes indicated that the sequence is highly redundant in several strains of M. hyorhinis, but that there is diversity in the sizes of restriction fragments detected among these strains. In contrast, repetition of the sequence was limited in M. hyopneumoniae and M. flocculare, and no homologies to this repeated element were apparent in mycoplasma species isolated from animal hosts other than the swine. The reiterated sequence may reflect intraspecies genomic diversification in M. hyorhinis and its selective presence in otherwise unrelated species raises the possibility that it has been horizontally transmitted between these organisms.

Bacteriophages↗

PubMed2006

Mycoplasma genitalium mg200 and mg386 genes are involved in gliding motility but not in cytadherence.

Isolation and characterization of transposon-generated Mycoplasma genitalium gliding-deficient mutants has implicated mg200 and mg386 genes in gliding motility. The proposed role of these genes was confirmed by restoration of the gliding phenotype in deficient mutants through gene complementation with their respective mg386 or mg200 wild-type copies. mg200 and mg386 are the first reported gliding-associated mycoplasma genes not directly involved in cytadherence. Orthologues of MG200 and MG386 proteins are also found in the slow gliding mycoplasmas, Mycoplasma pneumoniae and Mycoplasma gallisepticum, suggesting the existence of a unique set of proteins involved in slow gliding motility. MG200 and MG386 proteins share common features, such as the presence of enriched in aromatic and glycine residues boxes and an acidic and proline-rich domain, suggesting that these motifs could play a significant role in gliding motility.

Amino Acid Motifs↗

PubMed1990

Inhibitory effect of mycoplasma-released arginase. Activity in mixed-lymphocyte and tumour cell cultures.

Non-fermenting mycoplasma species deplete culture media for arginine through arginase activity linked to their arginine deiminase pathway, resulting in proliferation arrest and cell death in mycoplasma-contaminated cell cultures. The presence of only 2-3 Mycoplasma (M.) arginini-contaminated T cells in a one-way allogeneic mixed-lymphocyte culture (MLC) significantly inhibits development of cytotoxic T-cell activity. Likewise, strong degrees of inhibition are observed after addition of nanogram doses of M. arginini extracts (MAE) to MLC or cell proliferation cultures. M. arginini-induced cell inhibition can be reversed by addition of excess arginine to the culture medium. Antisera raised against non-fermenting, but not against fermenting, mycoplasma species block the inhibitory effect of MAE. SDS-PAGE separation of MAE disclosed a broad band at 60 kDa which contained arginase activity when assayed in MLC and cell proliferation culture. SDS-PAGE followed by western blotting and reaction with antisera raised against non-fermenting mycoplasma species demonstrated a band at 43 kDa common for these micro-organisms.

Animals↗

PubMed1999

Iscom is an efficient mucosal delivery system for Mycoplasma mycoides subsp. mycoides (MmmSC) antigens inducing high mucosal and systemic antibody responses.

The purpose of this study was to explore the iscom as a mucosal delivery system for Mycoplasma mycoides subsp. mycoides small colony (MmmSC) antigens. BALB/c female mice were immunised intranasally (i.n.) twice, 8 weeks apart with three different doses (3, 10 and 20 microg) or subcutaneously (s.c.) with 3 microg of M. mycoides antigens incorporated into iscoms. Mycoplasma cells were administered s.c. twice, 8 weeks apart at a dose of 3 microg or i.n. at 10 microg as for iscoms. Both i.n. and s.c. modes of immunisation with iscoms induced prominent primary serum antibody responses in a dose-dependent manner, which were efficiently boosted. Compared to whole mycoplasma cells, iscoms enhanced the total Ig and IgG subclass (IgG1, IgG2a and IgG2b) responses in serum and in lungs greatly, and this enhancement was more prominent after i.n. than after s.c. immunisation. By the i.n. mode of immunisation iscoms containing mycoplasma antigens induced a 60-fold higher IgA response in lungs than the whole cell antigen. Iscoms also induced substantially higher total Ig and IgG subclass responses in the lungs. By Western blot a reduced number of bands (7) were detected in lung secretion after both i.n. and s.c. immunisations with iscoms compared to a high number of bands (more than 30) detected by serum antibodies. Interestingly i.n. immunisation with iscoms induced antibodies in lungs as well as in serum to mycoplasma cell antigens which differed from those induced by s.c. immunisation as revealed by the Western blot patterns.

Animals↗

PubMed1990

Mycoplasma in relation to gingivitis and periodontitis.

In this study, mycoplasma were enumerated in the gingival crevicular fluid (GCF) of gingivitis and periodontitis patients. GCF samples were obtained from the mesial (approximal) gingival crevice or periodontal pocket of the maxillary right first permanent molar. Samples were cultured anaerobically on a medium selective for mycoplasmas as well as on a non-selective medium to obtain a total anaerobic count. Mycoplasmas were present in the GCF of both gingivitis and periodontitis patients, but a greater % was obtained from the GCF of patients with periodontitis. The proportions of mycoplasma appeared to be independent of the disease activity as expressed by bleeding on probing (PBI), but to be related to probable pocket depth, as shown by the higher %s in periodontitis than gingivitis for a given PBI. On the basis of an increased proportion in relation to disease severity, mycoplasmas would therefore appear to be amongst those micro-organisms associated with CIPD.

Adult↗

PubMed1970

Mycoplasma recovery from the male genitourinary tract: voided urine versus the urethral swab.

A study of Mycoplasma recovery from the genitourinary tract was made on a group of 50 males attending a venereal disease clinic. The purpose of the investigation was to compare recovery rates of mycoplasma from two types of clinical specimens-the urethral swab and voided urine. The total number of positive cultures did not differ significantly when either the swab or urine was used; Mycoplasma hominis type 1 was the only taxonomic species isolated, either alone or mixed with T-strain mycoplasma. Recovery rates of the two types from both the swab and the urine did not differ significantly. Age did not relate to the presence of mycoplasma in the group studied.

Adolescent↗

PubMed1976

Interaction of virulent Mycoplasma pneumoniae with hamster tracheal organ cultures.

Exposure of hamster tracheal organ cultures to virulent Mycoplasma pneumoniae leads to alterations in ribonucleic acid (RNA) and protein biosynthesis and metabolism of the respiratory epithelium. An examination of the turnover rates of RNA and protein in infected tracheal organ cultures indicates that the rates of degradation of both prelabeled host cell RNA and protein are similar to those of uninfected controls. Infected tracheal organ cultures shifted to a nonpermissive medium within 24 h after infection and further incubated in the nonpermissive medium for 72 or 96 h behaved as normal uninfected cultures in terms of metabolic precursor uptake. Under these conditions, mycoplasmas remained attached to the respiratory epithelium. Cell membranes prepared from virulent mycoplasmas by several procedures neither attached to nor altered the metabolic activity of tracheal cultures. These data indicate that the intimate contact between virulent mycoplasmas and the respiratory epithelium does not alone account for the subsequent interruption of host cell metabolism but must be accompanied by continued multiplication and biochemical function of attached mycoplasmas.

Animals↗

PubMed1982

Interaction of Mycoplasma hyopneumoniae with the porcine respiratory epithelium as observed by electron microscopy.

An in vivo-passaged strain of Mycoplasma hyopneumoniae attained viability titers of 10(6) to 10(8) color-changing units per mg of tissue in pig lungs and caused gross and histological pulmonic lesions. Mycoplasmas were readily located in the lumina of the respiratory tract by electron microscopy. In sections of tissue fixed in glutaraldehyde-osmium, the organisms were found to possess many radial fibrils on the outer surface of the limiting membrane. These fibrils appeared to interconnect adjacent mycoplasmas and to extend between the organism and epithelial cell. Ruthenium red staining demonstrated a thick, dark layer of capsular material enveloping the entire mycoplasma cell. The capsular material was seen to bridge the space between the mycoplasma and host cell. The general morphology of the in vitro-passaged strains grown in broth medium was essentially similar to that of the in vivo-passaged strain. In these organisms, however, no long fibrils were seen, although a fuzzy layer was present outside the cell membrane. The ruthenium red-positive capsule was stained less intensely, and its width was only about one-half that observed for the in vivo-passaged strain. In negatively stained preparations, the cells had an outer fringe of amorphous material apparently corresponding to the fuzzy layer seen in thin sections. The in vitro-passaged strain grew poorly in pig lungs and lost its ability to produce gross pulmonic lesions. The organisms in the respiratory tract had a capsule much thinner than that of the in vivo-passaged strain.

Animals↗

PubMed1982

Effects of ionophores and dicyclohexylcarbodiimide on Mycoplasma gallisepticum adherence to erythrocytes.

To test the influence of the electrochemical ion gradient across mycoplasma membranes on the capacity of organisms to adhere to host cells, Mycoplasma gallisepticum cells were treated with valinomycin, carbonylcyanide m-chlorophenylhydrazone, and N,N'-dicyclohexylcarbodiimide (DCCD) singly or in combination. Uptake of [3H]tetraphenylphosphonium by the treated cells was employed as a measure of the effects of the ionophores on membrane potential. In the absence of K+, valinomycin increased, whereas carbonylcyanide m-chlorophenylhydrazone, and DCCD decreased [3H]tetraphenylphosphonium uptake. However, with a high level of K+ or with DCCD, uptake of [3H]tetraphenylphosphonium in the presence of valinomycin decreased below control levels, indicating that, generally, the ionophores affected membrane potential in the expected manner. The treated organisms were tested for their capacity to attach to glutaraldehyde-fixed human erythrocytes. DCCD was the best inhibitor of mycoplasma attachment, and in combination with valinomycin attachment, capacity decreased by about 40%. The combination of valinomycin plus carbonylcyanide m-chlorophenylhydrazone was less effective; it decreased attachment by about 15 to 25%. It was concluded that the dissipation of ion gradients across cell membranes decreases only partially mycoplasma adherence, in line with previous findings that isolated mycoplasma membranes retain the major part of the attachment capacity of intact cells.

Adhesiveness↗

PubMed1983

Mycoplasma hyorhinis GDL surface protein antigen p120 defined by monoclonal antibody.

Four antigens of Mycoplasma hyorhinis GDL were defined by murine monoclonal antibodies. Components of broth-grown mycoplasmas were separated under reducing conditions by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and subsequent protein blots were stained with individual antibodies. Each antibody reacted with a distinct component with relative molecular weights of 120,000, 73,000, 51,000, and 38,000, respectively (termed p120, p73, p51, and p38). Trypsin treatment of protein blots specifically abrogated binding of antibodies, suggesting that the epitopes recognized were associated with proteins. By using indirect immunofluorescence and immunoferritin techniques, mycoplasmas colonizing the surface of chronically infected BW5147 murine T-lymphoblastoid cells were selectively stained with antibody to p120, indicating the localization of the corresponding epitope at the mycoplasma surface. Protein blots of mycoplasmas derived from BW5147 cell cultures were stained with antibody to p120, revealing a component identical to that observed with broth-grown organisms. These results establish the identity of a surface protein antigen of M. hyorhinis GDL expressed at the surface of organisms during their colonization of host cells.

Animals↗

PubMed1987

Triton X-114 phase fractionation of an integral membrane surface protein mediating monoclonal antibody killing of Mycoplasma hyorhinis.

A previously defined immunoglobulin M(kappa) monoclonal antibody reacting with a surface epitope of Mycoplasma hyorhinis is shown in this report to mediate specific, complement-dependent mycoplasmacidal activity. Immunoblot analysis of mycoplasma components and their tryptic cleavage products showed that the epitope recognized was present on a protein with an apparent molecular weight of 23,000 (p23) and on a limit tryptic fragment of this protein with an apparent molecular weight of 18,000 (p18). Both p23 and p18 are shown by Triton X-114 phase fractionation to partition efficiently into the hydrophobic detergent phase. Other antigens bearing epitopes not expressed at the cell surface were present among the numerous hydrophilic proteins found in the aqueous phase. The external orientation and membrane association of the p23 antigen were further established by demonstrating that trypsin treatment of intact mycoplasmas generated the antigenic p18 fragment, which remained tightly associated with the organism. These results localize an epitope responsible for antibody-mediated mycoplasma killing onto a specific, surface-exposed region of an integral membrane protein of this organism. Since the monoclonal antibody used in this study does not bind to the surface of all strains of M. hyorhinis, the epitope identified also defines a structural marker of antigenic surface variation within this species, a feature previously observed during serological classification of the organism. Analysis of the antigenic and structural features of the p23 surface antigen may therefore be useful in establishing mechanisms of surface antigen variation among integral membrane proteins of mycoplasmas that could dictate important antigenic characteristics recognized during chronic disease caused by these agents.

Antibodies, Monoclonal↗

PubMed1988

Evidence for occurrence of passively adsorbed I antigen activity on a cultured strain of Mycoplasma pneumoniae.

The aim of this study was to investigate whether I antigen occurs in association with Mycoplasma pneumoniae in a form that may be immunogenic during natural infection or experimental immunization. I antigen activity was detected by radioimmunoassay in suspensions of M. pneumoniae MY11965 and in the soluble phase of mycoplasma lysates prepared with Triton X-100. There was evidence for the occurrence of I antigen in at least two macromolecular forms. The first form partitioned in the lipid phase following chloroform-methanol extraction and chromatographed on thin-layer chromatograms as a ceramide decasaccharide. The second form was associated with the residue after lipid extraction and was solubilized by treatment with sodium dodecyl sulfate or pepsin; this component was tentatively designated a glycoprotein or polysaccharide and was not investigated further. In a lipid extract from mycoplasmas that had been surface labeled by the galactose oxidase-NaB3H4 method, two 3H-labeled glycolipids were detected as minor components which chromatographed on thin-layer chromatograms in the region of an authentic I-active ceramide decasaccharide. However, no significant radioactivity was incorporated into glycolipids after metabolic labeling with [3H]glucosamine. These observations suggested that the mycoplasmas contained surface-associated glycolipids with I antigen activity that were of exogenous origin. This was supported by the observations that horse, rabbit, and fetal calf sera contained I antigen activity and that the I antigen activity in M. pneumoniae cultures reflected the levels found in the sera included in the culture media. From rabbit serum, which expressed the highest antigen activity, an I-active glycolipid was isolated that chromatographed as a ceramide decasaccharide. I-active substances passively adsorbed onto M. pneumoniae are potentially immunogenic. However, we consider these unlikely to be the main stimulus for autoantibody production in natural infection, since the autoantibodies elicited are restricted to the I carbohydrate antigen and there is a lack of antibodies to other glycolipids that may be adsorbed from serous and cellular components of the host tissues. In our view, the more likely stimulus is the specific complex formed between the mycoplasma and the sialo-oligosaccharide receptors of the Ii antigen type, as suggested previously.

Animals↗

PubMed1988

Parasitism of hamster trachea epithelial cells by Mycoplasma pneumoniae.

Hamster trachea epithelial (HTE) cells were employed as a model system for Mycoplasma pneumoniae pathogenesis. To more closely mimic natural infection, M. pneumoniae was forced to rely upon host cells (as opposed to the growth medium) for nutrients, and infections were initiated with relatively low mycoplasma doses and monitored for extended time periods. A time- and dose-dependent decline in the viability of infected cells was observed; however, viability never declined below 50% of that in uninfected controls. Protein and RNA synthesis actually increased above control levels in infected cells, despite a concomitant decrease in viability. This response was pronounced at higher multiplicities of infection but was only transient at lower doses. In parallel studies in which a culture medium capable of supporting M. pneumoniae growth was used, loss of viability was accelerated. With a low-dose infection a transient increase followed by a precipitous decline in macromolecular synthesis was observed, relative to that in uninfected controls. At higher doses, however, macromolecular synthesis decreased dramatically and in proportion to the loss of viability. The requirement for HTE cells for mycoplasma growth under the experimental culture conditions was demonstrated by quantitating viable mycoplasmas in the culture medium in the presence or absence of HTE cells over 4 days. The increase in mycoplasma number was negligible in the absence of HTE cells, while a 30-fold increase was observed in the presence of HTE cells. These findings demonstrate the feasibility of long-term, low-dose studies of M. pneumoniae pathogenesis with trachea epithelial cells and a nonpermissive culture medium. This experimental system should facilitate the elucidation of the mechanism(s) responsible for host cell injury, and perhaps reveal how host cells respond to infection.

Animals↗

PubMed1994

A 48-kilodalton Mycoplasma fermentans membrane protein induces cytokine secretion by human monocytes.

Mycoplasma fermentans is one of several Mycoplasma species that have been reported to stimulate tumor necrosis factor (TNF) secretion from monocytes. This activity has been associated primarily with the mycoplasma membrane fraction. In this article, we have characterized a membrane protein that stimulates TNF and interleukin 1 beta secretion. The TNF-releasing activity partitioned into the Triton X-114 detergent phase, suggesting that the molecules is hydrophobic. The secretion of TNF is elevated in the presence of serum, which suggests that a serum component may play a role in the interaction between this mycoplasma protein and monocytes. Treatment of monocytes with monoclonal anti-CD14 antibody had no effect on the levels of TNF-releasing activity. By using the monocyte Western blot (immunoblot) technique, we have determined the molecular mass of the active molecule to be 48 kDa. This molecule appears to be distinct from the recently described family of variable lipoproteins of M. fermentans. Mycoplasma particulate material treated with proteinase K lost all inducing activity, whereas lipoprotein lipase-treated samples retained some level of activity.

Antigens, CD↗