Mycoplasma DnaK increases DNA copy number variants in vivo

The human microbiota affects critical cellular functions, although the responsible mechanism(s) is still poorly understood. In this regard, we previously showed that Mycoplasma fermentans DnaK, an HSP70 chaperone protein, hampers the activity of important cellular proteins responsible for DNA integrity. Here, we describe a novel DnaK knock-in mouse model generated in our laboratory to study the effect of M. fermentans DnaK expression in vivo. By using an array-based comparative genomic hybridization assay, we demonstrate that exposure to DnaK was associated with a higher number of DNA copy number variants (CNVs) indicative of unbalanced chromosomal alterations, together with reduced fertility and a high rate of fetal abnormalities. Consistent with their implication in genetic disorders, one of these CNVs caused a homozygous Grid2 deletion, resulting in an aberrant ataxic phenotype that recapitulates the extensive biallelic deletion in the Grid2 gene classified in humans as autosomal recessive spinocerebellar ataxia 18. Our data highlight a connection between components of the human urogenital tract microbiota, namely Mycoplasmas, and genetic abnormalities in the form of DNA CNVs, with obvious relevant medical, diagnostic, and therapeutic implications.

Analysis of DnaK Expression from a Strain of Mycoplasma fermentans in Infected HCT116 Human Colon Carcinoma Cells

Several species of mycoplasmas, including Mycoplasma fermentans, are associated with certain human cancers. We previously isolated and characterized in our laboratory a strain of human mycoplasma M. fermentans subtype incognitus (MF-I1) able to induce lymphoma in a Severe Combined Immuno-Deficient (SCID) mouse model, and we demonstrated that its chaperone protein, DnaK, binds and reduces functions of human poly-ADP ribose polymerase-1 (PARP1) and ubiquitin carboxyl-terminal hydrolase protein-10 (USP10), which are required for efficient DNA repair and proper p53 activities, respectively. We also showed that other bacteria associated with human cancers (including Mycoplasmapneumoniae, Helicobacterpylori, Fusobacteriumnucleatum, Chlamydiathrachomatis, and Chlamydia pneumoniae) have closely related DnaK proteins, indicating a potential common mechanism of cellular transformation. Here, we quantify dnaK mRNA copy number by RT-qPCR analysis in different cellular compartments following intracellular MF-I1 infection of HCT116 human colon carcinoma cells. DnaK protein expression in infected cells was also detected and quantified by Western blot. The amount of viable intracellular mycoplasma reached a steady state after an initial phase of growth and was mostly localized in the cytoplasm of the invaded cells, while we detected a logarithmically increased number of viable extracellular bacteria. Our data indicate that, after invasion, MF-I1 is able to establish a chronic intracellular infection. Extracellular replication was more efficient while MF-I1 cultured in cell-free axenic medium showed a markedly reduced growth rate. We also identified modifications of important regulatory regions and heterogeneous lengths of dnaK mRNA transcripts isolated from intracellular and extracellular MF-I1. Both characteristics were less evident in dnaK mRNA transcripts isolated from MF-I1 grown in cell-free axenic media. Taken together, our data indicate that MF-I1, after establishing a chronic infection in eukaryotic cells, accumulates different forms of dnaK with efficient RNA turnover.

Complexity of the Mycoplasma fermentans M64 genome and metabolic essentiality and diversity among mycoplasmas

Recently, the genomes of two Mycoplasma fermentans strains, namely M64 and JER, have been completely sequenced. Gross comparison indicated that the genome of M64 is significantly bigger than the other strain and the difference is mainly contributed by the repetitive sequences including seven families of simple and complex transposable elements ranging from 973 to 23,778 bps. Analysis of these repeats resulted in the identification of a new distinct family of Integrative Conjugal Elements of M. fermentans, designated as ICEF-III. Using the concept of “reaction connectivity”, the metabolic capabilities in M. fermentans manifested by the complete and partial connected biomodules were revealed. A comparison of the reported M. pulmonis, M. arthritidis, M. genitalium, B. subtilis, and E. coli essential genes and the genes predicted from the M64 genome indicated that more than 73% of the Mycoplasmas essential genes are preserved in M. fermentans. Further examination of the highly and partly connected reactions by a novel combinatorial phylogenetic tree, metabolic network, and essential gene analysis indicated that some of the pathways (e.g. purine and pyrimidine metabolisms) with partial connected reactions may be important for the conversions of intermediate metabolites. Taken together, in light of systems and network analyses, the diversity among the Mycoplasma species was manifested on the variations of their limited metabolic abilities during evolution.

Enzymatic synthesis of Mycoplasma fermentans specific glycoglycerophospholipid from 1,2-dipalmitoylglycerol

A gene, mf3, encoding glycosyltransferase in glycoglycerophospholipid (GGPL; GGPL-I and GGPL-III) biosynthesis in Mycoplasma fermentans PG18 was identified by genomic analysis, cloned, modified codon usage, and expressed in Escherichia coli. The mf3 gene consists of an open reading frame of 1221 bp encoding 406 amino acids. The mf3 gene product, Mf3, has 27% amino acid homology with glycosyltransferase of Borrelia burgdorferi but no homology to genes of other Mycoplasma species in the GenBank database. The reaction product of Mf3 using 1,2-dipalmitoilglycerol and UDP-glucose as substrates showed a specific sodium adducted ion at m/z 753, which corresponded to glucopyranosyl dipalmitoilglycerol as determined by MALDI-TOF mass spectrometry. Furthermore, in the reaction product by Mf3 and Mf1 which was a cholinephosphotransferase and previously cloned from M. fermentans PG18, an ion at m/z 896 corresponding to GGPL-I was detected by mass spectrometry. The product ions of choline, phosphocholine, and hexose-bound phosphocholine were detected by tandem MS analysis of protonated molecules at m/z 896. From these results, mf3 was identified as a glycosyltransferase. It was suggested that glucose transfer and phosphocholine transfer to 1,2-dipalmitoylglycerol are involved in the GGPL biosynthesis pathway of M. fermentans PG18.

An evaluation of PCR methods to detect strains of Mycoplasma fermentans

A panel of 30 putative Mycoplasma fermentans strains, isolated from various sources including human, ovine and cell lines, were tested by a previously described polymerase chain reaction (PCR) to confirm their identity by amplification of a conserved 206 bp region of the insertion sequence IS1550. In addition, the application of another PCR based on the major part of the IS1550 element showed one or two products of different length (1144 and 1341 bp) enabling M. fermentans strains to be divided into two types designated as Type A and Type B. A PCR, which amplifies the macrophage activating lipopeptide gene (malp), supported the identification of all the strains as M. fermentans. Thirteen other species of Mycoplasma from human sources gave negative results in these tests, with the exception of Mycoplasma orale, which was detected by both IS1550-PCRs based on the major part and the conserved 206 bp region of the IS1550 element. This study suggests that all M. fermentans isolates possess both the IS1550 element and the malp gene. In contrast to the IS1550, the malp gene is shown to be species-specific and the use of a malp PCR described here could prove to be a useful adjunct to IS1550 detection as confirmation of the presence of M. fermentans in clinical material.

Infection of human B lymphoma cells by Mycoplasma fermentans induces interaction of its elongation factor with the intracytoplasmic domain of Epstein-Barr virus receptor (gp140, EBV/C3dR, CR2, CD21)

Human cell lines are often infected by mycoplama strains. We have demonstrated that when infected by Mycoplasma fermentans, human B lymphoma cell proliferation increased strongly. These infected B cells expressed a p45 kDa protein which interacted with the intracellular domain of CD21, the EBV/C3d receptor. p45 analysis demonstrated that this is a new gene which encodes an elongation factor originating from Mycoplasma fermentans. p45 interaction with CD21 was specific, there being no interaction with CD19. This is the first demonstration that Mycoplasma fermentans, in infecting human B cells, generates a p45 Mycoplasma component that interacts with CD21, which is involved in B cell proliferation.

Relationship between structures and biological activities of mycoplasmal diacylated lipopeptides and their recognition by toll-like receptors 2 and 6

The lipopeptide FSL-1 [S-(2,3-bispalmitoyloxypropyl)-Cys-Gly-Asp-Pro-Lys-His-Pro-Lys-Ser-Phe, Pam(2)CGDPKHPKSF] synthesized on the basis of the N-terminal structure of a Mycoplasma salivarium lipoprotein capable of activating normal human gingival fibroblasts to induce the cell surface expression of ICAM-1 revealed an activity to induce production of monocyte chemoattractant protein 1, interleukin-6 (IL-6), and IL-8. FSL-1 also activated macrophages to produce tumor necrosis factor alpha as the Mycoplasma fermentans-derived lipopeptide MALP-2 (Pam(2)CGNNDESNISFKEK), a potent macrophage-activating lipopeptide, did. The level of the activity of FSL-1 was higher than that of MALP-2. This result suggests that the difference in the amino acid sequence of the peptide portion affects the activity because the framework structure other than the amino acid sequence of the former is the same as that of the latter. To determine minimal structural requirements for the activity of FSL-1, the diacylglyceryl Cys and the peptide portions were examined for this activity. Both portions did not reveal the activity. A single amino acid substitution from Phe to Arg and a fatty acid substitution from palmitic acid to stearic acid drastically reduced the activity. Similar results were obtained in measuring the NF-kappaB reporter activity of FSL-1 to human embryonic kidney 293 cells transfected with Toll-like receptor 2 and 6, together with a NF-kappaB-dependent luciferase reporter plasmid. These results suggest that both the diacylglyceryl and the peptide portions of FSL-1 are indispensable for the expression of biological activities and for the recognition by Toll-like receptors 2 and 6 and that the recognition of FSL-1 by Toll-like receptors 2 and 6 appears to be hydrophobic.

Presence of human mycoplasma DNA in gastric tissue samples from Korean chronic gastritis patients

We aimed to determine whether mycoplasmas are present in Korean chronic gastritis, and to understand their roles in gastric cancer tumorigenesis, because mycoplasmas resemble Helicobacter pylori in terms of ammonia production and induction of inflammatory cytokines in immune and non-immune cells. The presence and identity of mycoplasmas were assessed by semi-nested PCR and sequencing, and the results were compared with pathologic data. Fifty-six samples collected from Korean chronic gastritis patients were used for this study. Twenty-three (41.1%) were positive for mycoplasmas. Eighteen sequenced samples contained a single human mycoplasma or two mycoplasmas, which were identified as Mycoplasma faucium (13/18), M. fermentans (3/18), M. orale (1/18), M. salivarium (2/18), and M. spermatophilum (1/18). Mycoplasma-infected chronic gastritis samples showed significantly more severe neutrophil infiltration than non-infected samples (P = 0.0135). Mycoplasma profiles in the oral cavity (M. salivarium is major) and stomach were different, and the presence of significant proinflammatory responses in mycoplasma-positive patients suggests that the mycoplasmas are not simply contaminants. Further studies are required to understand whether mycoplasmas play a role in gastric tumorigenesis.

Characterization of an IS element in Mycoplasma orale that is highly homologous to M. fermentans ISLE

In a previous study, using a primer set designed from Mycoplasma fermentans, we amplified a PCR fragment from Mycoplasma orale similar to the 206-bp DNA fragment amplified from M. fermentans insertion-sequence-like element (ISLE). The presence of this similar ISLE fragment has the potential to cause confusion in the PCR diagnosis of M. fermentans and M. orale, which have significantly different clinical scenarios. An ISLE from three different M. orale strains was amplified by using a primer set designed from sequence within the left and right terminal stem and loop (S&L) structures flanking the ISLE of M. fermentans. Sequence analysis showed that the M. orale ISLE is 93% identical to that of M. fermentans at the nucleotide level and codes for two open reading frames also found in the M. fermentans ISLE. This is the first finding that two different mycoplasma species harbor highly homologous IS elements. This finding has great significance in clinical diagnosis and suggests a possibility of horizontal transfer of an IS element between two different mycoplasma species.

Molecular genetic analysis of ICEF, an integrative conjugal element that is present as a repetitive sequence in the chromosome of Mycoplasma fermentans PG18

Mycoplasma genomes contain compact gene sets that approach the minimal complement necessary for life and reflect multiple evolutionary instances of genomic reduction. Lateral gene transfer may play a critical role in shaping the mobile gene pool in these organisms, yet complex mobile elements have not been reported within this genus. We describe here a large ( approximately 23-kb) genetic element with unique features that is present in four copies in the Mycoplasma fermentans PG18 chromosome, accounting for approximately 8% of the genome. These novel elements, designated ICEF (integrative conjugal elements of M. fermentans), resemble conjugative, self-transmissible integrating elements (constins) in that circular, nonreplicative extrachromosomal forms occur in which the left and right termini of the integrated element are juxtaposed and separated by a coupling sequence derived from direct repeats flanking chromosomal copies of ICEF as a result of target site duplication. ICEF contain multiple similarly oriented open reading frames (ORFs), of which some have homology to products of known conjugation genes but others have no known counterparts. Surprisingly, unlike other constins, ICEF lack homologs of known integrases, transposases, or recombinases, suggesting that a novel enzyme may be employed for integration-excision. Skewed distribution and varied sites of chromosomal integration among M. fermentans isolates suggest a role for ICEF in promoting genomic and phenotypic variation in this species. Identification of homologs of terminal ICEF ORFs in two additional mycoplasma species indicates that ICEF is the prototype member of a family of ICE-related elements that may be widespread among pathogenic mycoplasmas infecting diverse vertebrate hosts.

Mutations in 23S rRNA account for intrinsic resistance to macrolides in Mycoplasma hominis and Mycoplasma fermentans and for acquired resistance to macrolides in M. hominis

The mechanisms of intrinsic resistance of Mycoplasma hominis to 14- and 15-membered macrolides were investigated in comparison with those of M. pneumoniae, which is naturally susceptible to macrolides. Radiolabeled erythromycin was not accumulated by M. hominis PG21, but addition of an ABC transporter inhibitor increased the level of erythromycin uptake more than two times, suggesting the existence of an active efflux process. The affinity of [(14)C]erythromycin to ribosomes isolated from M. hominis was dramatically reduced relative to that to ribosomes isolated from M. pneumoniae. The nucleotide sequences of 23S rRNA of both ribosomal operons rrnA and rrnB and ribosomal proteins L4 and L22 of M. hominis were obtained. Compared to the sequence of M. pneumoniae, M. hominis harbored a G2057A transition in its 23S rRNA sequence, as did M. fermentans, another mycoplasma that is erythromycin resistant. An additional C2610U change was also found in the sequence of M. hominis. Moreover, two M. hominis clinical isolates with acquired resistance to 16-membered macrolides were examined for mutations in domain II and domain V of 23S rRNA and in ribosomal proteins L4 and L22. Compared to the sequence of reference strain PG21, one isolate harbored a A2059G transition and a C2611U transition in one of the two rrn operons, while the other one was mutated only at position 2059, also on the same operon. No mutation was found in the two ribosomal protein sequences. Overall, the present study is an exhaustive characterization of the intrinsic resistance of M. hominis to 14- and 15-membered macrolides and the first description of mycoplasma clinical isolates resistant to macrolide, lincosamide, and streptogramin antibiotics harboring a mutation at position 2611 in the 23S rRNA.

Identification and functional mapping of the Mycoplasma fermentans P29 adhesin

Initial adherence interactions between mycoplasmas and mammalian cells are important for host colonization and may contribute to subsequent pathogenic processes. Despite significant progress toward understanding the role of specialized, complex tip structures in the adherence of some mycoplasmas, particularly those that infect humans, less is known about adhesins through which other mycoplasmas of this host bind to diverse cell types, even though simpler surface components are likely to be involved. We show by flow cytometric analysis that a soluble recombinant fusion protein (FP29), representing the abundant P29 surface lipoprotein of Mycoplasma fermentans, binds human HeLa cells and inhibits M. fermentans binding to these cells, in both a quantitative and a saturable manner, whereas analogous fusion proteins representing other mycoplasma surface proteins did not. Constructs representing nested N- or C-terminal truncations of FP29 allowed initial mapping of this specific adherence function to a central region of the P29 sequence containing a 36-amino-acid disulfide loop. A derivative of FP29 containing a mutation converting one participating Cys to Ser, precluding intrachain disulfide bond formation, retained full activity. Together these results suggest that the direct interaction of M. fermentans with a ligand on the HeLa cell surface involves a limited segment of the P29 surface lipoprotein and requires neither the disulfide bond nor the contribution of adjacent portions of the protein. Earlier results indicating phase-variable display of monoclonal antibody surface epitopes on P29, now recognized to be outside this ligand binding region, raise the possibility that variation of mycoplasma surface architecture might alter the presentation of the binding region and the adherence phenotype. Preliminary results further indicated that FP29 could inhibit binding to HeLa cells by Mycoplasma hominis, a distinct human mycoplasma species displaying the phase-variable adhesin Vaa, but not that by Mycoplasma capricolum, an organism infecting caprine species. This result raises the additional, testable possibility that a common host cell ligand for two human mycoplasma species may be recognized through structurally dissimilar adhesins that undergo phase variation by two distinct mechanisms, governing protein expression (Vaa) or surface masking (P29).

A lipoprotein family from Mycoplasma fermentans confers host immune activation through Toll-like receptor 2

Mycoplasma have been reported to be associated with human diseases. Three forms of a mycoplasma lipopeptide/protein with the ability to modulate the host immune system were independently identified and named macrophage-activating lipopeptide 2 (MALP-2), P48 and M161Ag (identical to MALP-404). Although these molecules had polypeptides of different sizes, they exerted similar immunomodulatory effects on macrophages/dendritic cells, such as cytokine induction, NO production and maturation of antigen-presenting cells (APCs). M161Ag exhibited complement-activating ability and bound macrophages via complement C3b/C3bi and their receptors. The diacylated N-terminal palmitates were involved in these activities. Toll-like receptor 2 (TLR2) was found to be responsible for these functional features of these mycoplasma products, except for complement activation. Here, we summarize the functional properties of this family of proteins, namely pathogen-associated molecular pattern (PAMP) and discuss its relationship to the reported pathogenesis of latent mycoplasma infection.

The prevalence of Mycoplasma fermentans in patients with inflammatory arthritides

OBJECTIVES

To search for evidence that Mycoplasma fermentans is involved in the pathogenesis of some forms of human arthritis by testing for the presence of mycoplasmal DNA in joint material.

METHODS

M. fermentans DNA was detected by the identification of a 104-base pair amplification product of the polymerase chain reaction (PCR).

RESULTS

M. fermentans DNA was detected in synovial fluid samples from six (17%) of 35 patients with rheumatoid arthritis (RA) and 18 (21%) of 85 patients with seronegative arthritis. These detection rates were significantly greater than in samples from patients with osteoarthritis or crystal synovitis, none of 26 of these being positive.

CONCLUSIONS

M. fermentans could be involved in the pathogenesis of some forms of inflammatory arthritis and this possibility is worthy of further study.

An association of disseminated Mycoplasma fermentans in HIV-1 positive patients with non-Hodgkin's lymphoma

We examined the relationship between the haematogenous dissemination of Mycoplasma fermentans and non-Hodgkin's lymphoma (NHL) in 265 HIV-1 positive patients. A polymerase chain reaction (PCR) assay was used to detect M. fermentans in peripheral blood mononuclear cells (PBMCs) from 50 patients enrolled consecutively from an HIV outpatient clinic in 1991 (cohort 1), 56 patients with lower respiratory tract infection who underwent bronchoscopy in 1992 (cohort 2), and 159 patients who were enrolled into a natural history cohort study in 1994 (cohort 3). The incidence of NHL among the patients was determined in 1998. The PBMCs of 29 patients (10.9%) were positive for M. fermentans (8 in cohort 1, 13 in cohort 2 and 8 in cohort 3) and 11 patients (4.2%) developed NHL which was confirmed histologically (3 in cohort 1, 4 in cohort 2 and 4 in cohort 3). We found a statistically significant association between the presence of M. fermentans and the development of NHL in the combined cohort (risk ratio [RR]=6.78 [95% confidence interval (CI) 2.21--20.84], P=0.003 Fisher's exact test [FET]). This association remained significant even after adjustment in a multivariate analysis for CD4 cell count and HIV disease status at the time of M. fermentans testing (RR=7.97 [95% CI=2.16--29.47], P=0.002).

IS1550 from Mycoplasma fermentans is transposable in Escherichia coli

An insertion sequence (IS)-like element (ISMil) was previously isolated from the incognitus strain of Mycoplasma fermentans. With polymerase chain reaction primers corresponding to the left and right terminal inverted repeats of ISMil, a 1.4-kb DNA fragment was amplified from the genome of the M64 strain of M. fermentans. This DNA fragment has structural characteristics similar to those of ISMil and is designated IS1550. One copy of IS1550 encoded two considerable overlapping open reading frames (ORFs), ORF1 and ORF2. A putative translation frame-shift signal AAAAAAG (A6G) was located near the 3'-end of ORF1. This signal might cause a -1 frame-shift to form a fused product of ORF1 and ORF2 with 444 amino acids, which has a significant similarity to the putative transposase of the IS3 family. This copy of IS1550 was shown to be transposable in Escherichia coli ISM612. Its transposition caused a 1465-bp deletion immediately adjacent to the 3'-end of the element and the creation of a pair of 3-bp direct repeats flanking the element at the new insertion site. On the basis of these results, IS1550 was considered a typical transposable element.

Induction of leukemia cell differentiation and apoptosis by recombinant P48, a modulin derived from Mycoplasma fermentans

P48 is a 48-kDa monocytic differentiation/activation factor which was originally identified in the conditioned medium of the Reh and other leukemia cell lines and has recently been shown to be a Mycoplasma fermentans gene product. Previously, conditioned medium P48 has been shown to induce differentiation of HL-60 (human promyelocytic leukemia) cells. Recently our laboratory isolated cDNA clones for P48 from Reh cells and genomic clones from Mycoplasma fermentans and expressed the recombinant protein as a maltose binding protein (MBP) fusion protein in E. coli. In this report we present the initial characterization of this recombinant P48 fusion protein (rP48-MBP). We show that rP48-MBP induces differentiation of HL-60, U937 (human histiocytic lymphoma), and M1 (mouse myeloid leukemia) cell lines. Interestingly, rP48-MBP also induces apoptosis of U937 and HL-60 cells as assessed by terminal transferase (TUNEL) assays. This is the first report of induction of apoptosis by a Mycoplasma gene product. P48 is a Mycoplasma-derived immunomodulatory molecule which has differentiation and apoptosis-inducing activities and may be important in the pathophysiology of Mycoplasma infections. The recombinant protein may be useful in studying the mechanisms of differentiation, cytokine production, and apoptosis in malignant and nonmalignant hematopoietic cells.

Detection of Mycoplasma fermentans in healthy students and patients with congenital immunodeficiency

OBJECTIVES

To determine the prevalence of M. fermentans at different anatomical sites in healthy subjects and in patients with congenital immunodeficiency, and to determine whether haematogenous invasion occurs among the latter.

METHODS

A polymerase chain reaction (PCR) assay was used to detect M.fermentans in throat swabs and urine specimens from healthy students, and from patients with congenital immunodeficiency. Peripheral blood mononuclear cells (PBMCs) from the latter group were also tested.

RESULTS

Sixty-two students provided throat swabs, of which 11 (18%) were M. Jermentans-positive; 46 provided urine specimens, of which eight (17%) were positive. Of the 45 students who provided both throat and urine specimens, 12 (27%) had M. fermentans-positive samples; four in the throat and urine, four in the throat only and four in the urine only. Nineteen of the 20 patients with congenital immunodeficiency provided throat swabs, of which one (5%) was M. fermentans-positive; 19 also provided urine specimens, of which three (16%) were positive. All of the immunodeficient patients provided a PBMC sample, but none was positive.

CONCLUSION

M. fermentans occurred frequently at mucosal sites in a healthy population and in subjects with congenital immunodeficiency. However, such a deficiency did not lead to overt haematogenous invasion.

IS1630 of Mycoplasma fermentans, a novel IS30-type insertion element that targets and duplicates inverted repeats of variable length and sequence during insertion

A new insertion sequence (IS) of Mycoplasma fermentans is described. This element, designated IS1630, is 1,377 bp long and has 27-bp inverted repeats at the termini. A single open reading frame (ORF), predicted to encode a basic protein of either 366 or 387 amino acids (depending on the start codon utilized), occupies most of this compact element. The predicted translation product of this ORF has homology to transposases of the IS30 family of IS elements and is most closely related (27% identical amino acid residues) to the product of the prototype of the group, IS30. Multiple copies of IS1630 are present in the genomes of at least two M. fermentans strains. Characterization and comparison of nine copies of the element revealed that IS1630 exhibits unusual target site specificity and, upon insertion, duplicates target sequences in a manner unlike that of any other IS element. IS1630 was shown to have the striking ability to target and duplicate inverted repeats of variable length and sequence during transposition. IS30-type elements typically generate 2- or 3-bp target site duplications, whereas those created by IS1630 vary between 19 and 26 bp. With the exception of two recently reported IS4-type elements which have the ability to generate variable large duplications (B. B. Plikaytis, J. T. Crawford, and T. M. Shinnick, J. Bacteriol. 180:1037-1043, 1998; E. M. Vilei, J. Nicolet, and J. Frey, J. Bacteriol. 181:1319-1323, 1999), such large direct repeats had not been observed for other IS elements. Interestingly, the IS1630-generated duplications are all symmetrical inverted repeat sequences that are apparently derived from rho-independent transcription terminators of neighboring genes. Although the consensus target site for IS30 is almost palindromic, individual target sites possess considerably less inverted symmetry. In contrast, IS1630 appears to exhibit an increased stringency for inverted repeat recognition, since the majority of target sites had no mismatches in the inverted repeat sequences. In the course of this study, an additional copy of the previously identified insertion sequence ISMi1 was cloned. Analysis of the sequence of this element revealed that the transposase encoded by this element is more than 200 amino acid residues longer and is more closely related to the products of other IS3 family members than had previously been recognized. A potential site for programmed translational frameshifting in ISMi1 was also identified.

Detection of Mycoplasma fermentans in saliva sampled from infants, preschool and school children, adolescents and adults by a polymerase chain reaction-based assay

Attempts were made to detect Mycoplasma fermentans in saliva sampled from 201 subjects (108 males and 93 females) aged from 4 months to 59 years by a polymerase chain reaction-based assay. M. fermentans was detected in saliva from 110 (54.7%) of 201 subjects, and 10 (28.6%) of 35 subjects aged from 4 months to 3 years. Of ten positive subjects, three were aged from 16 to 23 months and five were from 26 to 31 months. The incidence tended to increase with age up to the teens. The incidence was significantly greater in teenagers than in subjects aged from 7 to 12 years, but there was no significant difference in the incidence between the group of teenagers and each of the groups of subjects older than the teenagers. Thus, it was suggested that M. fermentans colonized the mouth at the age of about 16 months up to the age of 19 years.

Mycoplasma orale has a sequence similar to the insertion-like sequence of M. fermentans

Polymerase chain reaction (PCR) using the Mycoplasma fermentans insertion sequence-like element (ISLE) RW primer set amplifies DNA from Mycoplasma orale when more than 1 ng is present in the reaction tube. In this study, amplified products from 11 different clinical isolates and the ATCC prototype of M. orale were sequenced and compared to 206 bp amplicons from eight isolates and the ATCC strain of M. fermentans. The nucleotide sequences of the amplified M. orale products had high sequence homology (88-92%) to those from M. fermentans, but differed at several key positions. The M. orale products contained a DraI restriction enzyme site not found in any of the M. fermentans amplified products. Consistent with this finding, the PCR products from M. orale were digested by DraI while the PCR products from M. fermentans were resistant to DraI digestion. The results suggest that M. orale may carry a similar IS-like element that complicates but does not negate using the ISLE PCR assay designed to detect M. fermentans. It appears possible for the RW primers to amplify M. orale if the mycoplasmas are present at higher concentrations. The amplified products can be differentiated from those from M. fermentans by a rapid DraI restriction endonuclease digestion or by Southern blot analysis using the RW006 internal probe under highly stringent conditions.

Differential posttranslational processing confers intraspecies variation of a major surface lipoprotein and a macrophage-activating lipopeptide of Mycoplasma fermentans

The malp gene of Mycoplasma fermentans is shown to occur in single copy but to encode two discrete translated forms of lipid-modified surface protein that can be differentially expressed on isolates within this species: MALP-2, a 14-amino-acid (2-kDa) lipopeptide with potent macrophage-stimulatory activity (P. F. Mühlradt, M. Kiess, H. Meyer, R. Süssmuth, and G. Jung, J. Exp. Med. 185:1951-1958, 1997), and MALP-404, an abundant, full-length (404-amino-acid) surface lipoprotein of 41 kDa, previously designated P41 (K. S. Wise, M. F. Kim, P. M. Theiss, and S.-C. Lo, Infect. Immun. 61:3327-3333, 1993). The sequences, transcripts, and translation products of malp were compared between clonal isolates of strains PG18 (known to express P41) and II-29/1 (known to express high levels of MALP-2). Despite conserved malp DNA sequences containing full-length open reading frames and expression of full-length monocistronic transcripts in both isolates, Western blotting using a monoclonal antibody (MAb) to the N-terminal MALP-2 peptide revealed marked differences in the protein products expressed. Whereas PG18 expressed abundant MALP-404 with detectable MALP-2, II-29/1 revealed no MALP-404 even in samples containing a large comparative excess of MALP-2. Colony immunoblots with the MAb showed uniform surface expression of MALP-2 in II-29/1 populations. A second MAb to an epitope of MALP-404 outside the MALP-2 sequence predictably failed to stain II-29/1 colonies but uniformly stained PG18 populations. Collectively, these results provide evidence for novel posttranscriptional (probably posttranslational) processing pathways leading to differential intraspecies expression of a major lipoprotein, and a potent macrophage-activating lipopeptide, on the surface of M. fermentans. In the course of this study, a striking conserved motif (consensus, TD-G--DDKSFNQSAWE--), designated SLA, was identified in MALP-404; this motif is also distributed among selected lipoproteins and species from diverse bacterial genera, including Bacillus, Borrelia, Listeria, Mycoplasma, and Treponema. In addition, malp was shown to flank a chromosomal polymorphism. In eight isolates of M. fermentans examined, malp occurred upstream of an operon encoding the phase-variable P78 ABC transporter; but, in three of these isolates, a newly discovered insertion sequence, IS1630 (of the IS30 class), was located between these genes.

Detection of Mycoplasma genus and Mycoplasma fermentans by PCR in patients with Chronic Fatigue Syndrome

Mycoplasma fermentans and other Mycoplasma species are colonizers of human mucosal surfaces and may be associated with human immunodeficiency virus infection. While many infectious agents have been described in different percentages of patients with Chronic Fatigue Syndrome (CFS), little is known about the prevalence of mycoplasmas and especially M. fermentans in CFS patients. A polymerase chain reaction (PCR)-based assay was used to detect Mycoplasma genus and M. fermentans genomes in peripheral blood mononuclear cells (PBMC) of CFS patients. Blood was collected from 100 patients with CFS and 50 control subjects. The amplified products of 717 bp of Mycoplasma genus, and 206 bp of M. fermentans were detected in DNA purified from blood samples in 52% and 34% of CFS samples, respectively. In contrast, these genomes were found in only 14% and 8% of healthy control subjects respectively (P < 0.0001). All samples were confirmed by Southern blot with a specific probe based on internal sequences of the expected amplification product. Several samples, which were positive for Mycoplasma genus, were negative for M. fermentans indicating that other Mycoplasma species are involved. A quantitative PCR was developed to determine the number of M. fermentans genome copies present in 1 microg of DNA for controls and CFS patients. Mycoplasma copy numbers ranging from 130 to 880 and from 264 to 2400 were detected in controls and CFS positive subjects, respectively. An enzyme immunoassay was applied for the detection of antibodies against p29 surface lipoprotein of M. fermentans to determine the relationship between M. fermentans genome copy numbers and antibody levels. Individuals with high genome copy numbers exhibited higher IgG and IgM antibodies against M. fermentans specific peptides. Isolation of this organism by culture from clinical specimens is needed in order to demonstrate specificity of signal detected by PCR in this study.

Multiplex PCR for the detection of Mycoplasma fermentans, M. hominis and M. penetrans in cell cultures and blood samples of patients with chronic fatigue syndrome

A multiplex polymerase chain reaction (PCR) was initially developed to detect the presence of mycoplasma genus DNA sequences in cell cultures and to differentiate between three human pathogenic mycoplasma species simultaneously. The assay in turn, proved to be a useful tool for the detection of mycoplasma infection in human DNA samples. One set of oligonucleotide primers which are specific for a highly conserved region among all members of the genus mycoplasma along with three other primer sets which are specific for Mycoplasma fermentans, Mycoplasma hominis andMycoplasma penetrans species were used in this assay. The sensitivity of detection was determined by infecting peripheral blood mononuclear cells (PBMC) of healthy individuals with known bacterial copy numbers from each species, extracting the DNA, and subjecting 1 microgram of DNA from each sample to 40 cycles of amplification. By using agarose gel electrophoresis the detection level was determined to be 7, 7, 9 and 15 mycoplasma cells per microgram of human genomic DNA for M. genus,M. fermentans, M. hominis and M. penetrans, respectively. The assay was applied to DNA extracted from the PBMCs of individuals suffering from chronic fatigue syndrome (CFS) (n=100) as determined by the Center for Disease Control (CDC) criteria, and compared to healthy individuals (n=100). The percentage of M. genus infection was found to be 52% in CFS patients and only 15% in healthy individuals. Mycoplasma fermentans, M. hominis andM. penetrans were detected in 32, 9 and 6% of the CFS patients while they were detected in 8, 3 and 2% of the healthy control subjects, respectively. This assay provides a rapid and cost efficient procedure to screen either cell cultures or clinical samples for the presence of three potentially pathogenic species of mycoplasma with a high level of sensitivity and specificity.

Mycoplasma fermentans DNA is infrequently detected in urine specimens from renal transplant recipients

Mycoplasma fermentans is a likely causative agent of HIV-associated nephropathy. In a pilot study, M. fermentans DNA was detected with polymerase chain reaction (PCR) in urine samples from renal allograft recipients; nine (39.1%) out of 23 renal allograft recipients (most of whom had chronic allograft rejection) and none of the 20 controls, were infected with M. fermentans. A cross-sectional study was conducted to investigate the prevalence of M. fermentans in urine samples from renal allograft recipients. Midstream urine samples were centrifuged at 13,000 x g, purified with QIAamp and tested with PCR using RW004/RW005 and an internal control to screen for the presence of inhibitors. Of the 264 participants recruited, 263 completed the questionnaire (172 men, 92 women); 53 had chronic renal allograft rejection, 106 had chronic renal dysfunction without rejection, 69 had a normal renal allograft for more than 3 months and 35 had a renal allograft for less than 3 months. All urine samples yielded positive results for the internal control. Mycoplasma fermentans DNA was detected once i prospectively collected urine samples. The only individual infected with M. fermentans was also seropositive for HIV-1. This study demonstrates that M. fermentans can be at most sporadically detected in urine from patients living with a renal allograft but is not implicated in chronic rejection of allograft.

High-frequency DNA rearrangements in the chromosomes of clinically isolated Mycoplasma fermentans

Mycoplasma fermentans is currently being examined as an agent potentially associated with human disease. Several strains of M. fermentans were isolated from patients with respiratory tract disease and AIDS. Two of these clinical strains, M64 and SK6, were triple-filter-cloned and designated as the parental clones in this study. Genomic DNA of randomly picked subclones in four and five subsequent generations passed from the parental M64 and SK6 clones were analyzed by using a radiolabeled M. fermentans-specific insertion sequence (IS)-like element as the probe. The hybridization patterns of DNA restriction fragments revealed high frequencies of chromosomal changes accompanied with excision or new insertion of the IS-like element in M. fermentans chromosome. The findings indicate M. fermentans has an effective mechanism(s) to produce a rapid gene rearrangement that may be mediated by one or more copies of the IS-like element.

Structural and functional properties of complement-activating protein M161Ag, a Mycoplasma fermentans gene product that induces cytokine production by human monocytes

Human malignant cells are targeted by homologous complement C3b if they express M161Ag, a 43-kDa protein with C3-activating property. cDNA of M161Ag cloned from human leukemia cell lines predicted M161Ag as a novel secretory protein comprised of 428 amino acids including 5 amino acids encoded by TGA codons (Matsumoto M., Takeda, J., Inoue, N., Hara, T., Hatanaka, M., Takahashi, K., Nagasawa, S., Akedo, H., and Seya, T. (1997) Nat. Med. 3, 1266-1270), although the origin of this gene was obscure. Here we clarified this point through genomic and biochemical analysis: 1) 5'-UT and genomic sequences represented the prokaryote promoter and ribosomal binding site; 2) the TGA codons in M161Ag cDNA were translated not into selenocysteines but into tryptophans; 3) M161Ag anchored onto the membrane secondary to its N-terminal palmitoylation like prokaryote lipoproteins; 4) genomic and cDNA clones of M161Ag were highly homologous to Mycoplasma fermentans gene encoding P48, a monocytic differentiation/activation factor, recently released in the data base, although the resultant proteins were different in the amino acid sequences. Additionally, purified soluble M161Ag efficiently provoked IL-1beta, tumor necrosis factor alpha, and IL-6 like P48, and further IL-10 and IL-12 in human peripheral blood monocytes. Thus, M161Ag originates from M. fermentans, and latently infected M. fermentans allows human cells to produce M161Ag. The liberated protein serves as a potent modulator of innate and cellular immune responses via its complement-activating and cytokine-producing activities.

Genotypic and phenotypic analysis of Mycoplasma fermentans strains isolated from different host tissues

A correlation was found between the expression of a specific Mycoplasma fermentans surface antigen (Pra, proteinase-resistant antigen) and the site of isolation of the organism from the infected host. Strains which expressed Pra were most frequently associated with cells of bone marrow origin, and strains which lacked expression of Pra were most commonly isolated from the respiratory tract, genital tract, and arthritic joints, i.e., epithelial cell surfaces. Pra was previously shown to be resistant to degradation by proteinases and was hypothesized to play a protective role at the organism surface and perhaps to influence which host tissue site was colonized by the organism. The methods used for this phenotyping scheme required isolation and growth of the mycoplasma in quantities sufficient for immunoblot analysis using monoclonal antibodies. We wanted to determine a more rapid and less cumbersome technique to supplement this method for determining the Pra phenotype directly in clinical specimens. Here we describe PCR studies to investigate the movement of a previously identified M. fermentans insertion sequence (IS)-like element. These data showed a correlation between a specific IS genotype and the Pra+ phenotype. Production of a 160-bp product using a single set of IS-based primers was associated with expression of Pra. The genomic IS location resulting in the 160-bp product was determined by using Southern blot analysis and was found to be a stable insertion site characteristic of genotype I strains. Additional analyses of sequences within and flanking the IS insertion sites revealed another pair of PCR primer sites which resulted in the consistent production of a 450-bp amplicon. The stability of this site was dependent on the absence of the IS-like element between the primer sites. The production of this 450-bp amplicon correlated with the Pra mutant phenotype and was characteristic of genotype II strains. The data showed that the sequence within the IS may be unstable and that reliable genotyping sequences are more easily found in the stable genomic sites which flank the IS element.

Sequencing multimegabase-template DNA with BigDye terminator chemistry

Using the recently introduced BigDye terminators, large-template DNA can be directly sequenced with custom primers on automated instruments. Cycle sequencing conditions are presented to sequence DNA samples isolated from a number of microbial genomes including 750-kb Ureaplasma urealyticum, 1.2-Mb Mycoplasma fermentans, 2.3-Mb Streptococcus pneumoniae, and 4.6-Mb Escherichia coli. Average read lengths of >700 bp from unique primer annealing sites are often sufficient to fill final gaps in microbial genome sequencing projects without additional manipulations of template DNA. The technique can also be applied to sequence-targeted regions, thereby bypassing tedious subcloning steps.

Absence of mycoplasmal gene in malignant mammalian cells transformed by chronic persistent infection of mycoplasmas

Chronic persistent infections by mycoplasmas induced malignant transformation of C3H mouse embryo cells that normally had never been reported to undergo spontaneous transformation. This mycoplasma-mediated oncogenic process had a long latency (more than 7 weeks of continuous mycoplasmal infection) and showed a multistage progression characterized by reversibility (at least up to 11 weeks of mycoplasmal infection) and irreversibility of malignant properties upon removal of the mycoplasma from culture. Further prolonged infections (18 weeks) by Mycoplasma fermentans or M. penetrans resulted in permanent transformation of these C3H cells that no longer required the continued presence of the transformation-inducing mycoplasmas in cultures to retain their malignant properties. Previous studies of viral oncogenesis revealed that virus-transformed cells always had viral gene(s) present. Integration of viral gene(s) apparently played an important role in the process of oncogenesis. In this study, we examined if the continued presence of any mycoplasmal gene(s) in mammalian cells, in whatever form, was also crucial in causing malignant cell transformation. Representational difference analysis (RDA) was a recently developed powerful technique to compare differences between two complex genomes. In the RDA system, subtractive and kinetic enrichment was used to purify and isolate restriction endonuclease gene fragment(s) of mycoplasmal origin, presumably present only in mycoplasma-transformed C3H cells, but not in nonmycoplasma-exposed control C3H cells. After three rounds of subtractive hybridization following PCR enrichment for each of three different restriction enzymes DNA digests, no gene fragment of mycoplasmal origin was amplified or identified in the permanently transformed C3H cells. Differing from tumorigenesis in animal cells induced by most oncogenic viruses or in plant cells induced by Agrobacteria, mycoplasmas evidently did not cause malignant transformation by integrating their gene(s) into the mammalian cell genome.

Genotypic characterization of seven strains of Mycoplasma fermentans isolated from synovial fluids of patients with arthritis

We performed a genotypic characterization of seven strains of Mycoplasma fermentans which have been isolated from the synovial fluid of patients with rheumatoid arthritis (n = 2), spondyloarthropathy (n = 1), and unclassified arthritis (n = 4). We compared them to three reference strains (strains PG18 and K7 and incognitus strain) and to a clinical isolate from the urethra of a patient with nongonococcal urethritis. The characterization methods included electrophoresis of native DNA, arbitrarily primed PCR, and restriction fragment length polymorphism analysis following conventional and pulsed-field gel electrophoresis. Southern blot analysis with a probe internal to an insertion sequence was performed with the restriction products produced by the last two techniques. No extrachromosomal DNA sequences were detected. The M. fermentans strains identified by these methods did not present a unique profile, but they could be separated into two main categories: four articular isolates were genetically related to PG18 and the three other isolates, the urethral isolate, and the incognitus strain were related to K7. We also looked for the presence of the bacteriophage MAV1 (associated with the arthritogenic property of Mycoplasma arthritidis in rodents) in the M. fermentans strains. MAV1 DNA was not detected in either the clinical isolates or the reference strains of M. fermentans.

The ftsZ gene as a tool for detection of Mycoplasma fermentans

Mycoplasma fermentans was reported as a common contaminant of cell cultures, and was shown to either induce or suppress several immunological functions. A strain of M. fermentans was recently isolated from a mouse T-lymphoma cell line, which differs from other M. fermentans strains by its growth characteristics and was designated (in the authors' records) as strain 609. Using the differential display technique (DD), a differentially expressed gene that was identified as the M. fermentans 609 ftsZ gene was isolated. Comparison of the nucleotide sequence of the M. fermentans 609 ftsZ gene to other ftsZ genes showed a 98% homology with Mycoplasma fermentans strain K7 and approximately 50% homology with Mycoplasma pulmonis and Mycoplasma genitalium. Comparison of the putative amino acid sequences of the FtsZ proteins showed similar homology. A polymerase chain reaction (PCR) assay to detect the presence of this ftsZ gene was established; it is a fast and convenient assay to detect infection of cells by the M. fermentans species. This work demonstrates that: (i) DD can be used as a useful technique to identify and isolate mycoplasmal genes from infected cells; and (ii) the ftsZ gene can be a useful marker to distinguish between different species of mycoplasma.

Variability in the distribution and composition of insertion sequence-like elements in strains of Mycoplasma fermentans

Mycoplasma fermentans has been reported to be pathogenic for man. All fourteen strains tested contain an insertion sequence-like element (ISLE) which may be present in multiple copies. To determine whether ISLE copies are similarly distributed in different strains of M. fermentans, restriction enzyme digest fragments of genomic DNA from 14 isolates, from a variety of sources, were separated by electrophoresis, blotted and hybridized to a biotin labelled polymerase chain reaction (PCR) amplified fragment of ISLE. A range of patterns was observed suggesting that the element has a tendency to undergo rearrangement within the genome. Analysis of ISLE sequences revealed inter- and intra-strain polymorphisms.

Localized frameshift mutation generates selective, high-frequency phase variation of a surface lipoprotein encoded by a mycoplasma ABC transporter operon

The wall-less mycoplasmas have revealed unusual microbial strategies for adaptive variation of antigenic membrane proteins exposed during their surface colonization of host cells. In particular, high-frequency mutations affecting the expression of selected surface lipoproteins have been increasingly documented for this group of organisms. A novel manifestation of mutational phase variation is shown here to occur in Mycoplasma fermentans, a chronic human infectious agent and possible AIDS-associated pathogen. A putative ABC type transport operon encoding four gene products is identified. The 3' distal gene encoding P78, a known surface-exposed antigen and the proposed substrate-binding lipoprotein of the transporter, is subject to localized hypermutation in a short homopolymeric tract of adenine residues located in the N-terminal coding region of the mature product. High-frequency, reversible insertion/deletion frameshift mutations lead to selective phase variation in P78 expression, whereas the putative nucleotide-binding protein, P63, encoded by the most 5' gene of the operon, is continually expressed. Mutation-based phase variation in specific surface-exposed microbial transporter components may provide an adaptive advantage for immune evasion, while continued expression of other elements of the same transporter may preserve essential metabolic functions and confer alternative substrate specificity. These features could be critical in mycoplasmas, where limitations in both transcriptional regulators and transport systems may prevail. This study also documents that P63 contains an uncharacteristic hydrophobic sequence between predicted nucleotide binding motifs and displays an amphiphilic character in detergent fractionation. Both features are consistent with an evolutionary adaptation favoring integral association of this putative energy-transducing component with the single mycoplasma membrane.

Antisignature oligonucleotides and their analogs as inhibitors of mollicutes-cofactors of HIV

Inhibition of mollicutes by synthetic oligonucleotides and their analogs complementary to specific "signature" regions of 16S rRNA and corresponding sequences of ribosomal operon DNA was studied. It was shown that antisignature oligonucleotides inhibited transcription in vitro for above 79% interacting specifically with ribosomal operon and non-specific with DNA-dependent RNA-polymerase. The inhibition efficiency depended on oligonucleotide sequence and type of modification. Translation in vitro was suppressed most efficiently (up to 60%) by oligonucleotides complementary to 3'-end region of 16S rRNA, also depending on their modification. Translation in vivo was inhibited most efficiently (up to 73%) by thiophosphate analogs of oligonucleotides complementary to sequences 499-507 and 523-532 of 16S rRNA responsible for binding of ribosomal "core" protein S4 starting the assembly of 30S ribosome subunit. With the simultaneous use of the last two oligonucleotides, the growth of mollicutes in SM IMV-72 medium rich in exogenous sources of nucleosides was suppressed for over 90%. It is supposed that under conditions where mollicutes have no free access to starting materials for their own synthesis of nucleic acid these nucleotides could suppress microorganisms completely. Antisignature oligonucleotides are considered as superspecific agents not leading to the development of resistance of mollicutes and believed to be the main future remedy against diseased caused by microorganisms lacking the system of nucleoside synthesis.

cDNA and genomic cloning and expression of the P48 monocytic differentiation/activation factor, a Mycoplasma fermentans gene product

P48 is a 48 kDa monocytic differentiation/activation factor previously purified from the conditioned medium of the Reh human pre-B cell leukaemia cell line. It induces growth arrest and differentiation of HL-60 human promyelocytic leukaemia cells along the monocytic pathway and the production of the cytokines interleukin 1, tumour necrosis factor-alpha and interleukin 6 in human monocytes and monocytic cell lines. The cDNA for P48 was cloned from Reh cellular RNA using 3' reverse amplification of cDNA ends. Southern blot probing with P48 cDNA revealed hybridization with DNA from Reh and Molt-4 cells, but not with DNA from human peripheral blood mononuclear cells. Subsequent studies using PCR and Southern analysis revealed P48 sequences in DNA isolated from Mycoplasma fermentans but not M. hominis, M.iowae, M.synoviae or M.lypophilum. Although initial studies using Mycoplasma culture and hybridization techniques had failed to reveal Mycoplasma infection in our Reh and Molt-4 cell lines, subsequent PCR studies using Mycoplasma genus-specific rRNA primrs revealed Mycoplasma sequences in these cell lines. Using the P48 cDNA probe, we isolated a genomic clone from M. fermentans DNA which was found to be 98.5% identical with the P48 cDNA clone, and the deduced amino acid sequence agreed with N-terminal microsequencing data for P48 protein purified from the Reh cell line conditioned medium. The 5' end of the gene has a number of consensus sequences characteristic of prokaryotic genes, and the deduced amino acid sequence has a number of features suggesting that P48 is a lipoprotein. The P48 cDNA was expressed in pMAL in Escherichia coli, and the 60 kDa expressed fusion protein was found to react with anti-P48 antibodies on Western blots. This is consistent with a pMAL fusion protein representing the sum of the 42 kDa maltose-binding protein and 18 kDa of P48 recombinant protein, suggesting that native P48 has significant post-translational modification. Consistent with this, Northern blot studies revealed a single 1 kb transcript. The recombinant fusion protein was found to possess anti-proliferative activity against HL-60 cells, and antibodies against recombinant P48 were found to block the biological activity of native P48 isolated from conditioned medium. These studies demonstrate that P48, a molecule with immunomodulatory and haematopoietic differentiation activities, is derived from M. fermentans or a closely related species. P48 may be important in the pathophysiology of Mycoplasma infections and may be useful in dissecting the mechanisms involved in mammalian haematopoietic cell differentiation, immune function and cytokine biosynthesis.

Search for the presence of six Mycoplasma species in peripheral blood mononuclear cells of subjects seropositive and seronegative for human immunodeficiency virus

The prevalence of Mycoplasma fermentans, Mycoplasma pirum, Mycoplasma genitalium, Mycoplasma pneumoniae, Mycoplasma hominis, and Mycoplasma penetrans was investigated by using specific PCR assays with peripheral blood mononuclear cells from subjects infected or not infected with the human immunodeficiency virus (HIV). Only M. fermentans was detected in 5.8% of 154 HIV-seropositive and 11.1% of 90 HIV-seronegative subjects.

Antigenic topology of the P29 surface lipoprotein of Mycoplasma fermentans: differential display of epitopes results in high-frequency phase variation

Antibodies to P29, a major lipid-modified surface protein of Mycoplasma fermentans, reveal phase variation of surface epitopes occurring with high frequency in clonal lineages of the organism. This occurs despite continuous expression of the entire epitope-bearing P29 product (detected by Western immunoblotting) and contrasts with phase variation of other surface antigens mediated by differential expression of proteins. To understand the structure and antigenic topology of P29, the single-copy p29 gene from strain PG18 was cloned and sequenced. The gene encodes a prolipoprotein containing a signal sequence predicted to be modified with lipid and cleaved at the N-terminal Cys-1 residue of the mature P29 lipoprotein. The remaining 218-residue hydrophilic sequence of P29 is predicted to be located external to the single plasma membrane. Additional Cys residues at positions 91 and 128 in the mature protein were shown to form a 36-residue disulfide loop by selectively labeling sulfhydryl groups that were liberated only after chemical reduction of monomeric P29. Two nearly identical charged amino acid sequences occurred in P29, within the disulfide loop and upstream of this structure. Two distinct epitopes binding different monoclonal antibodies were associated with opposite ends of the P29 protein, by mapping products expressed in Escherichia coli from PCR-generated 3' deletion mutations of the p29 gene. Each monoclonal antibody detected high-frequency and noncoordinate changes in accessibility of the corresponding epitopes in colony immunoblots of clonal variants, yet sequencing of the p29 gene from these variants and analysis of disulfide bonds revealed no associated changes in the primary sequence or disulfide loop structure of P29. These results suggest that P29 surface epitope variation may involve masking of selected regions of P29, possibly by other surface components undergoing phase variation by differential expression. Differential masking may be an important mechanism for altering the antigenic or functional surface topology of this mycoplasma and other wall-less mycoplasmas.

Detection of Mycoplasma fermentans in human saliva with a polymerase chain reaction-based assay

Mycoplasma fermentans and other mycoplasma species may be associated with human immunodeficiency virus infection. Little is known about the ecology of this micro-organism and its natural habitat. A polymerase chain reaction (PCR)-based assay was used to detect M. fermentans in whole saliva. The hypothesis was tested that M. fermentans is present on the mucosal surfaces of the mouth and oropharynx. Whole saliva was collected from 110 adults. The 206-bp amplification product of DNA purified from these samples was detected in ethidium bromide-stained 6% polyacrylamide gels in 49 (44%) samples tested. All samples were confirmed by Southern blotting with a probe based on an internal sequence of the expected amplification product. The data suggest that this organism is often found in saliva and on oropharyngeal mucosal surfaces. Saliva may play a part in its transmission between individuals. Saliva sampling may be helpful in further studies of the ecology and distribution of the micro-organism in human populations.

Development of an amplification and hybridization assay for the specific and sensitive detection of Mycoplasma fermentans DNA

A polymerase-chain-reaction-based detection system for Mycoplasma fermentans was established. The highly conserved tuf gene, which encodes elongation factor Tu of prokaryotes, served as target sequence for the PCR. With two PCR oligodeoxynucleotides, which were selected from M. fermentans specific sequences of the tuf gene, we amplified a 850 base pair DNA fragment. Via the biotin-moiety of one primer the PCR fragments were immobilized on streptavidin-coated microtitre plates. After alkaline denaturation a digoxigenin-labelled M. fermentans specific DNA probe was hybridized to the single stranded immobilized PCR fragment. Detection was performed by addition of an alkaline phosphatase conjugated anti-digoxigenin antibody. 4-methyl-umbelliferyl-phosphate was used as a fluorogenic substrate. Amplification of 10 fg chromosomal target DNA was detected by this 'DNA enzyme immuno assay (DEIA)' technique, corresponding to seven genome copies. Our study supports the presumption that the tuf gene proves to be a suitable target sequence for the PCR based detection of any bacterial species. Furthermore, hybridization of PCR fragments with radio-labelled DNA probes should no longer be necessary, because a very sensitive non-radioactive test system can easily be established with the 'DEIA' technique.

Identification of mycoplasma membrane proteins by systematic Tn phoA mutagenesis of a recombinant library

Wall-less prokaryotes in the genus Mycoplasma include over 90 species of infectious agents whose pathogenicity for humans and other animals is currently being assessed. Molecular characterization of surface proteins is critical in this regard but is hampered by the lack of genetic systems in these organisms. We used TnphoA transposition to systematically mutagenize, in Escherichia coli, a genomic plasmid library constructed from Mycoplasma fermentans, a potential human pathogen. The strategy circumvented problems of expressing mycoplasma genes containing UGA (Trp) codons and relied on the construction of the vector pG7ZCW, designed to reduce TnphoA transposition into vector sequences. Functional phoA gene fusions directly identified genes encoding 19 putative membrane-associated proteins of M. fermentans. Sequences of fusion constructs defined three types of export sequence: (1) non-cleavable, membrane-spanning sequences, (2) signal peptides with signal peptidase (SPase) I-like cleavage sites, and (3) signal peptides with SPase II-like lipoprotein-cleavage sites which, like most other mycoplasmal lipoprotein signals analysed to date, differed from those in several Gram-negative and Gram-positive eubacteria in their lack of a Leu residue at the -3 position. Antibodies to synthetic peptides that were deduced from two fusions to predicted lipoproteins, identified corresponding amphiphilic membrane proteins of 57 kDa and 78 kDa expressed in the mycoplasma. The P57 sequence contained a proline-rich N-terminal region analogous to an adhesin of Mycoplasma gallisepticum. The P78 protein was identical to a serologically defined phase-variant surface lipoprotein. TnphoA mutagenesis provides an efficient means of systematically characterizing functionally diverse lipoproteins and other exported proteins in mycoplasmas.

Molecular biological bases of resistance to HIV/AIDS (the hypothesis with elements of the theory)

Proceeding from the structure and function of the shell glycoprotein gp120 of the human immunodeficiency virus (HIV) and receptor glycoprotein CD4 on target cells for this virus, the author assumes that in nature there is genetically determined human resistance to the HIV infection and AIDS. This resistance manifests itself indirectly via products of the glycosylation system and via the composition and order of amino-acid residues in receptor CD4 sites responsible for interaction between the receptor and glycoprotein gp120. The author thinks that people in whom the glycosylation system determines either B(III) or AB(IV) blood groups are potential subjects of the HIV infection. But development of AIDS necessitates some conditions more, one of them is susceptibility of the human organism to be infected with mollicute Mycoplasma fermentans. This mycoplasma is able to recognize terminal NeuAc alpha 2-3 Gal in the composition of oligosaccharides of gp120, which permits it to adhere HIV virions on itself and then to transport them directly to the cells expressing receptor CD4 and having oligosaccharides of the same terminal structure. Oligosaccharides of glycocalyx of the mycoplasma protect it from the action of the human immune system and the mycoplasma, having "transported" HIV virions to target cells combines with membranes of the latter, stimulates formation by them of interleukin-1 and tumour necrosis factor, the known effectors of this virus reproduction. On the basis of all these factors the author identifies four types of human resistance to HIV/AIDS.

Taxonomy of the feline mycoplasmas Mycoplasma felifaucium, Mycoplasma feliminutum, Mycoplasma felis, Mycoplasma gateae, Mycoplasma leocaptivus, Mycoplasma leopharyngis, and Mycoplasma simbae by 16S rRNA gene sequence comparisons

The nucleotide sequence of the 16S rRNA gene of eight mycoplasmas isolated from felids was determined and used for taxonomic comparisons. A signature nucleotide sequence motif and overall sequence similarity to other mollicutes positioned Mycoplasma felifaucium, Mycoplasma felis, Mycoplasma leocaptivus, Mycoplasma leopharyngis, and Mycoplasma simbae in the Mycoplasma fermentans phylogenetic group of mollicutes. Mycoplasma arginini and Mycoplasma gateae were positioned in the Mycoplasma hominis phylogenetic group of mollicutes, and Mycoplasma feliminutum was positioned in the phylogenetically distant Acholeplasma group of mollicutes, showing that host family preference does not necessarily derive from bacterial phylogenetic closeness.

An unusual rRNA gene organization in Mycoplasma fermentans (incognitus strain)

The macro-restriction map of Mycoplasma fermentans (incognitus strain) was constructed and its rRNA genes were located on the map. It was found that this organism contains two sets of rRNA genes. The 16S and 23S rRNA genes were closely linked as two clusters. However, both 5S rRNA genes were separated from the 16S and 23S genes. The two 16S-23S rRNA gene clusters were arranged in an unusual tail to tail orientation.

[The use of an amplification test system for detecting persistent mycoplasmas]

A DNA amplification test system for the detection of Mycoplasma fermentans in clinical specimens was developed. The system was used for the analysis of biological specimens obtained from experimentally infected animals. The infective agent could be detected during the whole period of observation (6 months). High sensitivity of the polymerase chain reaction made it possible to detect M.fermentans in much greater number of cases than with the use of serological techniques.

Differential protein expression and surface presentation generate high-frequency antigenic variation in Mycoplasma fermentans

Mycoplasma fermentans, a wall-less prokaryote, is currently under investigation as a potential human pathogen. Recently, several surface lipoproteins have been shown to vary in expression between M. fermentans strains. Using specific antibodies to these lipoproteins, we investigated the extent and nature of antigenic variation within this species. Immunoscreening of type strain PG18 agar-grown colonies revealed marked heterogeneity in expression of distinct surface lipoproteins. Subsequent isolation and propagation of clonal isolates established isogenic lineages which displayed high-frequency (10(-2) to 10(-5) per generation) antigenic phase variation. [35S]cysteine-labeled protein profiles and Western immunoblots of phase-variant clones showed that several distinct integral membrane proteins undergo noncoordinate variation in expression. In addition to differential expression of epitope-bearing lipoproteins, differential accessibility of epitopes to antibodies was also documented as a mechanism generating surface phenotypic variation. Examination of one strain-variant antigen showed high-frequency phase variation to underlie previously observed antigenic differences between strains of this species. Thus, M. fermentans has a complex system capable of creating rapid changes in surface mosaics. This may profoundly affect mycoplasma-host interactions and may limit the methods by which populations of M. fermentans may be studied in vivo.

Use of the polymerase chain reaction for detection of Mycoplasma fermentans and Mycoplasma genitalium in the urogenital tract and amniotic fluid

In an attempt to further define the natural history of Mycoplasma genitalium and Mycoplasma fermentans infections in humans, we used cultures and the polymerase chain reaction (PCR) to determine whether these organisms were present in the urethra and cervix of sexually active adults and in the amniotic fluid of women whose membranes were intact and collected at the time of cesarean delivery (to preclude cervical contamination). M. genitalium was detected by PCR but not by culture in 11% of patients with urethritis or cervicitis. It was not detected by either PCR or culture in the 232 amniotic fluid samples analyzed. In contrast, M. fermentans was not detected by either method in patients with urethritis or cervicitis but was detected by PCR in 4 of 232 amniotic fluid samples tested. These results indicate that in these four cases M. fermentans was transferred transplacentally. Histological evidence of chorioamnionitis was present in two of the four patients, a finding suggesting that M. fermentans may be a cause of chorioamnionitis. These results must be confirmed by other investigators, and further studies should be undertaken to determine the potential clinical significance of M. fermentans infection.

Fatal systemic infections of nonhuman primates by Mycoplasma fermentans (incognitus strain)

Four silvered leaf monkeys inoculated with Mycoplasma fermentans (incognitus strain) showed wasting syndromes and died in 7-9 months. Infected animals had a late and transient antibody response to mycoplasmal infection. Three monkeys revealed periodic mycoplasmal antigenemia. The one that had the most persistent antigenemia failed to mount a detectable antibody response and was the first to die of the infection. The control monkey was killed 8 months later, after the last of the infected animals had died, and revealed no evidence of seroconversion or antigenemia. Polymerase chain reaction, immunohistochemical, and electron microscopic studies identified systemic infections of M. fermentans in the infected animals. No other opportunistic infection or neoplastic disease was found. It is interesting to note the absence of an inflammatory reaction to the large number of mycoplasmas in the infected tissues. M. fermentans (incognitus strain) apparently suppressed normal inflammatory or immune responses, produced wasting syndromes, and caused a fatal systemic infection in these monkeys.