Association of Mycoplasma penetrans with human immunodeficiency virus infection

Evaluation of Nanopore Sequencing as a Diagnostic Tool for the Rapid Identification of Mycoplasma bovis from Individual and Pooled Respiratory Tract Samples

Rapid identification of Mycoplasma bovis infections in cattle is a key factor to guide antimicrobial therapy and biosecurity measures. Recently, Nanopore sequencing became an affordable diagnostic tool for both clinically relevant viruses and bacteria, but the diagnostic accuracy for M. bovis identification is undocumented. Therefore, in this study Nanopore sequencing was compared to rapid identification of M. bovis with matrix-assisted laser desorption ionization-time of flight mass spectrometry (RIMM) and a triplex real-time PCR assay in a Bayesian latent class model (BLCM) for M. bovis in bronchoalveolar lavage fluid (BALf) samples obtained from calves. In practice, pooling of samples is often used to save money, but the influence on diagnostic accuracy has not been described for M. bovis. Therefore, a convenience sample of 17 pooled samples containing 5 individual BALf samples per farm was analyzed as well. The results for the pooled samples were compared with those for the individual samples to determine sensitivity and specificity. The BLCM showed good sensitivity (77.3% [95% credible interval, 57.8 to 92.8%]) and high specificity (97.4% [91.5 to 99.7%]) for Nanopore sequencing, compared to RIMM (sensitivity, 93.0% [76.8 to 99.5%]; specificity, 91.3% [82.5 to 97.0%]) and real-time PCR (sensitivity, 94.6% [89.7 to 97.7%]; specificity, 86.0% [76.1 to 93.6%]). Sensitivity and specificity of pooled analysis for M. bovis were 85.7% (95% confidence interval, 59.8 to 111.6%) and 90.0% (71.4 to 108.6%%), respectively, for Nanopore sequencing and 100% (100% to 100%) and 88.9% (68.4 to 109.4%) for RIMM. In conclusion, Nanopore sequencing is a rapid, reliable tool for the identification of M. bovis. To reduce costs and increase the chance of M. bovis identification, pooling of 5 samples for Nanopore sequencing and RIMM is possible.

Mycoplasma penetrans bacteremia in an immunocompromised patient detected by metagenomic sequencing: a case report

BACKGROUND

Mycoplasma sp. are well recognized as etiological agents of respiratory and sexually transmitted disease. Mycoplasma penetrans, a species of Mycoplasma sp., has been frequently detected in HIV-positive patients and associated with the progression of HIV-associated disease. To date, there is only a single case report describing M. penetrans as the causative agent of a severe respiratory tract infection in a HIV-negative patient.

CASE PRESENTATION

In this report, we describe the case of M. penetrans bacteremia in a HIV-negative, 38-year-old, female, immunocompromised, solid organ transplant patient (combined kidney and pancreas transplantation in 2016), who was admitted to our hospital with anemic uterine bleeding and fever of 38.3 °C. Several hours before her admission at our university hospital, a latex bladder catheter was inserted into her uterus and she complained about fatigue, dizziness and ongoing vaginal bleeding. Laboratory examination showed severe anemia, but microbiological examination was inconspicuous (culture negative vaginal and cervical smears, negative urine culture). Bacterial blood cultures showed a growth signal after 4 h, but microscopic examination with Gram staining and subcultures on different agar media did not identify bacterial pathogens. To identify the bacterial cause of malignancy in the patient, metagenomic sequencing of the blood culture was performed that identified M. penetrans.

CONCLUSION

Metagenomic sequencing identified M. penetrans in an immunosuppressed patient with culture-negative bacteremia. Clinicians should be aware of the opportunistic potential of M. penetrans that may cause severe infections in certain vulnerable patient populations and the limitations of culture and Gram staining for confirming the presence of fastidious bacterial pathogens like Mycoplasma spp.

Mollicutes/HIV Coinfection and the Development of AIDS: Still Far from a Definitive Response

Background. Mycoplasmas are known to cause various infections in humans, mainly in the respiratory and urogenital tracts. The different species are usually host-specific and cause diseases in well-defined sites. New species have been isolated, including those from HIV-infected persons. Summary. Its in vitro properties, combined with clinical findings, have led to the hypothesis that these microorganisms may act as cofactors of HIV in AIDS development. Even today this point of view is quite polemic among infectious disease specialists and many aspects remain to be clarified, in contrast to what happens, for instance, with HIV/Mycobacterium tuberculosis coinfection. Dozens of papers have been published covering aspects of Mollicutes/HIV coinfection, but they add little to no information about the putative contribution of Mollicutes to the evolution of AIDS. Very few researchers have devoted their efforts to trying to answer this question, which remains open. In this review, we discuss the evidences that may support this statement in the light of current knowledge in the field of mycoplasmology.

Mycoplasmas infection in male HIV/AIDS patients in Jiangsu, China

Mycoplasmas are widely distributed among animals, plants, and human. The four species namely, Mycoplasmas genitalium(Mg), Mycoplasmas fermentans(Mf), Mycoplasmas pentrans(Mpe), Mycoplasmas pirum(Mpi) are also called AIDS-associated mycoplasmas due to their involvement in the development and outcome of AIDS. To investigate the infection prevalence of Mg, Mf, Mpe and Mpi among male HIV/AIDS patients in Jiangsu Province and to analyze the relationship between pathogenic mycoplasmas and cellular immune function of them. First void urine and venous blood samples were collected and epidemiology questionnaires were administered after informed consent. Nested PCR was performed to determine the infection of Mg, Mf, Mpe and Mpi while ELISA assay was applied to detect interleukin-2(IL-2), interferon-γ(IFN-γ) and tumor necrosis factor-α(TNF-α). SAS 9.0 software was applied to analyze the data. A total of 713 HIV/AIDS patients were recruited in this study. The overall infection rates of Mg, Mf, Mpe and Mpi are 27.9%, 9.7%, 1.0% and 18.4% respectively. Generally, the infection rates of Mg(χ(2) = 10.311, P = 0.006) and Mpi were declined as the CD4+ cell counts increased, while Mf infection was higher in CD4+ T cell>350/μl group. The levels of cytokines are different with the variance of mycoplasmas infection. Mycoplasma infection among male HIV/AIDS patients is associated with changes in cellular immune response (cytokines). However, the affect of mycoplasmas on the immune function is complex, further studies are still required to elucidate whether mycoplasmas interact with HIV by interfering host immune system.

The prevalence of six species of Mycoplasmataceae in an HIV/AIDS population in Jiangsu Province, China

This study employed culture and polymerase chain reaction (PCR) to examine the prevalence of Ureaplasma urealyticum, Mycoplasma hominis, Mycoplasma genitalium, Mycoplasma fermentans, Mycoplasma penetrans and Mycoplasma pirum in 210 HIV/AIDS patients, 455 sexually transmitted infection (STI) clinic attendees and 245 healthy volunteers from first-void urine specimens for men and endocervical swabs for women. U. urealyticum and M. hominis were detected in 107 (51.0%) and 69 (32.9%) patients in the HIV/AIDS group. At least one of the other four organisms was detected in 34 (16.2%) HIV/AIDS patients, 29 (6.4%) STI clinic attendees and six (2.5%) healthy volunteers. This study showed that U. urealyticum, M. hominis and M. fermentans were significantly more prevalent in HIV/AIDS patients, as were other mycoplasmas. Our results suggest a possible role for co-infection.

High prevalence of Mycoplasma genitalium among female sex workers in Honduras: implications for the spread of HIV and other sexually transmitted infections

This study describes HIV, sexually transmitted infections (STI) and risk factors associated with Mycoplasma genitalium among female sex workers (FSWs) in four cities in Honduras. In 2006, 795 FSWs from Tegucigalpa, San Pedro Sula, La Ceiba and Comayagua were recruited using respondent-driven sampling (RDS) and tested for HIV prevalence and STI. HIV prevalence ranged from no infections in Comayagua to 5.4% in Tegucigalpa. With the exception of Comayagua, more than 20% of FSWs were infected with M. genitalium. M. genitalium in the aggregated cities was associated with HIV positivity, being aged ≤30 years old, drinking alcohol more than once weekly and always using condoms with regular clients in the past month. In comparison with a 2001 surveillance study we found lower rates of HIV infection. Interventions for HIV control and prevention among FSWs, including promotion of condom use, are needed in Honduras.

Antiphospholipid syndromes in infectious diseases

Antiphospholipid antibodies are essential in the diagnosis of antiphospholipid syndrome (APS), or the classic "Hughes syndrome," which is a systemic disorder that is autoimmune in nature. They are also found in various infections in low titers without any evidence of thrombotic manifestations of APS. However, in a few infections, when antiphospholipid antibodies are associated with protein cofactor, there can be associated thrombosis. Different infections are also responsible for triggering a subset of lethal APS, acute catastrophic APS. This situation requires prompt diagnosis and aggressive treatment of the infection to prevent severe complications.

Mycoplasma penetrans infections and seroconversion in patients with AIDS: identification of major mycoplasmal antigens targeted by host antibody response

We examined Mycoplasma penetrans-specific antibodies in sera of five male homosexual AIDS patients from whom M. penetrans was isolated during the disease process. No consistent immune reaction pattern could be recognized in Western blot using whole cell proteins. Serum samples obtained prior to M. penetrans isolation reacted with a number of M. penetrans proteins, most likely due to non-specific cross-reactions. Further analysis revealed that patients produced prominent antibody reaction to lipid-associated membrane proteins (LAMPs) of M. penetrans at the time of mycoplasma isolation, which could not be observed for serum samples obtained prior to M. penetrans isolation. The positive antibody reaction was mainly directed against two major LAMPs of M. penetrans with molecular mass of 35 and 38 kDa and produced a distinctive pattern of positive immunoreaction bands. Our observation suggested that, comparing with whole mycoplasmal proteins, LAMPs were more specific target antigens in serological assays for M. penetrans infection.

Mycoplasmas and ureaplasmas as neonatal pathogens

The genital mycoplasmas represent a complex and unique group of microorganisms that have been associated with a wide array of infectious diseases in adults and infants. The lack of conclusive knowledge regarding the pathogenic potential of Mycoplasma and Ureaplasma spp. in many conditions is due to a general unfamiliarity of physicians and microbiology laboratories with their fastidious growth requirements, leading to difficulty in their detection; their high prevalence in healthy persons; the poor design of research studies attempting to base association with disease on the mere presence of the organisms in the lower urogenital tract; the failure to consider multifactorial aspects of diseases; and considering these genital mycoplasmas only as a last resort. The situation is now changing because of a greater appreciation of the genital mycoplasmas as perinatal pathogens and improvements in laboratory detection, particularly with regard to the development of powerful molecular nucleic acid amplification tests. This review summarizes the epidemiology of genital mycoplasmas as causes of neonatal infections and premature birth; evidence linking ureaplasmas with bronchopulmonary dysplasia; recent changes in the taxonomy of the genus Ureaplasma; the neonatal host response to mycoplasma and ureaplasma infections; advances in laboratory detection, including molecular methods; and therapeutic considerations for treatment of systemic diseases.

Trypanosoma cruzi trans-sialidase as a new therapeutic tool in the treatment of chronic inflammatory diseases: possible action against mycoplasma and chlamydia

The present paper proposes a new therapy using Trypanosoma cruzi trans-sialidase to treat diseases with unclear pathogenesis that present in common chronic inflammation and fibrosis. This hypothesis is based on recent findings that co-infection with mycoplasma and chlamydia is present in many of these diseases and that this enzyme was capable to eliminate or decrease the co-infection from the host. We identified that mycoplasmas and chlamydias are present in atherosclerosis, aortic valve stenosis, dilated cardiomyopathy, chronic chagasic myocarditis and cancer. We hypothetized that mycoplasmal infection may induce immunodepression in the host, favoring proliferation of pre-existent chlamydial infection and that elimination of mycoplasma would lead to improvement of the immune system resistance and the control of chlamydial proliferation. Mycoplasma has a particular parasitic relationship with host cells, involving strong adherence of their membranes, making it extremely difficult to eradicate mycoplasmal infection from the host. A new therapeutic approach is suggested using one or more agents that prevent or inhibit the adherence of mycoplasma to host cell membranes by removing sialic acid residues and preventing oxidation of the cells. The use of a neuraminidase enzyme, particularly the T. cruzi trans-sialidase enzyme, associated with treatment using anti-oxidating agents is proposed. Preliminary experimental animal and laboratory tests showed good results. The proposal that trans-sialidase from T. cruzi is efficient in combating co-infection of mycoplasma and chlamydia is based, at least in part, on the observation that chagasic patients suffering from T. cruzi infection present less mycoplasma and chlamydia infection in their tissues. Also, a lower incidence of the diseases above described to be related to mycoplasma infection is observed in chagasic patients. It is also hypothesized that co-infection with mycoplasma and chlamydia may induce oxidation of the host cells. Anti-oxidants such as those present in plant extracts may also be used in the treatment. Other diseases such as chronic hepatitis, glomerulonephritis, Multiple Sclerosis, Alzheimer's Syndrome and idiopathic encephalitis are other examples of chronic diseases where mycoplasma and chlamydia might be present, as they have the characteristics of unknown etiology, persistent chronic inflammation and fibrosis.

Multiple promoter inversions generate surface antigenic variation in Mycoplasma penetrans

Mycoplasma penetrans is a newly identified species of the genus MYCOPLASMA: It was first isolated from a urine sample from a human immunodeficiency virus (HIV)-infected patient. M. penetrans changes its surface antigen profile with high frequency. The changes originate from ON<==>OFF phase variations of the P35 family of surface membrane lipoproteins. The P35 family lipoproteins are major antigens recognized by the human immune system during M. penetrans infection and are encoded by the mpl genes. Phase variations of P35 family lipoproteins occur at the transcriptional level of mpl genes; however, the precise genetic mechanisms are unknown. In this study, the molecular mechanisms of surface antigen profile change in M. penetrans were investigated. The focus was on the 46-kDa protein that is present in M. penetrans strain HF-2 but not in the type strain, GTU. The 46-kDa protein was the product of a previously reported mpl gene, pepIMP13, with an amino-terminal sequence identical to that of the P35 family lipoproteins. Nucleotide sequencing analysis of the pepIMP13 gene region revealed that the promoter-containing 135-bp DNA of this gene had the structure of an invertible element that functioned as a switch for gene expression. In addition, all of the mpl genes of M. penetrans HF-2 were identified using the whole-genome sequence data that has recently become available for this bacterium. There are at least 38 mpl genes in the M. penetrans HF-2 genome. Interestingly, most of these mpl genes possess invertible promoter-like sequences, similar to those of the pepIMP13 gene promoter. A model for the generation of surface antigenic variation by multiple promoter inversions is proposed.

The complete genomic sequence of Mycoplasma penetrans, an intracellular bacterial pathogen in humans

The complete genomic sequence of an intracellular bacterial pathogen, Mycoplasma penetrans HF-2 strain, was determined. The HF-2 genome consists of a 1 358 633 bp single circular chromosome containing 1038 predicted coding sequences (CDSs), one set of rRNA genes and 30 tRNA genes. Among the 1038 CDSs, 264 predicted proteins are common to the Mycoplasmataceae sequenced thus far and 463 are M.penetrans specific. The genome contains the two-component system but lacks the essential cellular gene, uridine kinase. The relatively large genome of M.penetrans HF-2 among mycoplasma species may be accounted for by both its rich core proteome and the presence of a number of paralog families corresponding to 25.4% of all CDSs. The largest paralog family is the p35 family, which encodes surface lipoproteins including the major antigen, P35. A total of 44 genes for p35 and p35 homologs were identified and 30 of them form one large cluster in the chromosome. The genetic tree of p35 paralogs suggests the occurrence of dynamic chromosomal rearrangement in paralog formation during evolution. Thus, M.penetrans HF-2 may have acquired diverse repertoires of antigenic variation-related genes to allow its persistent infection in humans.

Phase variation among major surface antigens of Mycoplasma penetrans

The pathogenicity and prevalence of Mycoplasma penetrans, a Mycoplasma species recently isolated from humans, are still debated. A major P35 antigen, which is used as target epitope in serological assays, was shown to be a phase-variable lipid-associated membrane protein (LAMP). In this study, we performed a comparative analysis of the LAMP patterns from five M. penetrans clinical isolates and from the type strain. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles and immunoblots with sera serially collected from an M. penetrans-infected patient indicated that these strains expressed different LAMP repertoires. Furthermore, the intraclonal variation in the expression of LAMPs (P34A, P34B, P35, and P38) was monitored by immunoblot analysis with three specific monoclonal antibodies (MAbs) developed in this study and MAb 7 to P35. The phase variation of these LAMPs occurs in an independent manner, with frequencies of variation ranging from 10(-2) to 10(-4) per cell per generation. Consistent with their amphipathic nature, the P34B and P38 antigens were found exposed at the cell surface. The DNA sequence encoding the P38 antigen was defined and found to be related to those of the P35 gene and other putative LAMP-encoding genes, suggesting that these variable antigens are encoded by a family of related genes. Finally, the serum samples from an M. penetrans-infected patient contained antibodies that reacted with a P36 antigen expressed in different M. penetrans strains but not in the isolate recovered from this patient. This result suggested that in vivo phase variation of P36 occurred, which would support a role for these LAMP variations in avoiding the host's immune vigilance.

Specific microbial colonizations in the periodontal sites of HIV-infected subjects

The purpose of this study was to examine colonization by specific organisms at periodontal sites in HIV-seropositive [HIV(+)] subjects. A total of 67 HIV(+) and 32 HIV(--) subjects were investigated. The specific pathogens included black-pigmented anaerobic rods (BPAR), Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Candida albicans and mycoplasma species. P. gingivalis was present in the HIV(+) subjects more frequently than in the HIV(--) periodontitis patients (P < 0.01). The cell numbers of BPAR and P. gingivalis and percentages as the total of CFUs on blood agar cultured in an anaerobic chamber were statistically higher in periodontal pocket samples from HIV(+) than from HIV(--). A. actinomycetemcomitans was also detected at a high rate (41.8%) in HIV(+) patients. The average cell numbers of C. albicans were higher in samples from the HIV(+) group (P < 0.05). The detection rate of mycoplasma species in the HIV(+) patients was significantly lower than that in HIV(--) subjects (P < 0.05), and most isolated mycoplasma strains were Mycoplasma salivarium.

Interactions between mycoplasma lipoproteins and the host immune system

Mycoplasmas typically have a number of distinct lipoproteins anchored on the outer face of the plasma membrane. These surface antigens have a potent modulin activity and are preferential targets of the host immune response. However, the variation of some of these lipoproteins provides mycoplasmas with an effective means of evading the host immune defence system.

Evaluation of IgG, IgM, and IgA antibodies to mycoplasma penetrans detected by ELISA and immunoblot in HIV-1-infected and STD patients, in São Paulo, Prazil

The aim of the present study was to determine the frequency of IgG, IgA, and IgM antibodies to Mycoplasma penetrans in HIV-1-infected patients and in patients with sexually transmitted diseases. We tested serum samples from 106 HIV-1-positive patients and 110 individuals with clinical symptoms of urethritis. ELISA and the immunoblot test were performed using M. penetrans lipid associated membrane proteins as antigen. By ELISA, we found a higher frequency (P < 0.05) of IgG against M. penetrans in HIV-1-infected and STD patients (25.5 and 17.3%) than in controls (1.2%), as well as a higher frequency of IgA (P < 0.05) (15.1 and 17.3% compared to 1.2%). For IgM, no differences were observed (P >/= 0.05) (3.8, 9.1, and 5. 8%, respectively). When the frequencies of IgG, IgM, and IgA antibodies of the HIV-1-infected patients were compared taking into account the CD4/CD8 cell ratios < 0.3 and >/= 0.3, no significant differences were observed between the two groups (13.3, 10, and 20%, compared to 20, 0, and 5%, respectively) (P > 0.05), possibly due to the low number of samples on which we could perform T-cell counts (53/106). The M. penetrans peptide of 38 kDa, considered immunodominant, was recognized in immunoblot by 51.8% of positive sera by ELISA for IgG, 50.0% for IgM, and 75% for IgA in the AIDS patients group, and by 47.4, 60.0, and 75.0%, respectively, in the sexually transmitted disease group. Cross-reactions in immunoblot for IgG were observed in sera from individuals infected with Mycoplasma pneumoniae and Mycoplasma hominis, and cross-reactions in immunoblot for IgA were observed in sera from individuals infected with M. hominis; all of them were ELISA negative to M. penetrans.

Role of Mycoplasma penetrans endonuclease P40 as a potential pathogenic determinant

Recently, we reported the purification to homogeneity and characterization of Ca(2+)- and Mg(2+)-dependent endonuclease P40 produced by Mycoplasma penetrans (M. Bendjennat, A. Blanchard, M. Loutfi, L. Montagnier, and E. Bahraoui, J. Bacteriol. 179; 2210-2220, 1997), a mycoplasma which was isolated for the first time from the urine of human immunodeficiency virus-infected patients. To evaluate how this nuclease could interact with host cells, we tested its effect on CEM and Molt-4 lymphocytic cell lines and on peripheral blood mononuclear cells. We observed that 10(-7) to 10(-9) M P40 is able to mediate a cytotoxic effect. We found that 100% of cells were killed after 24 h of incubation with 10(-7) M P40 while only 40% cytotoxicity was obtained after 72 h of incubation with 10(-9) M P40. Phase-contrast microscopy observations of P40-treated cells revealed morphological changes, including pronounced blebbing of the plasma membrane and cytoplasmic shrinkage characteristic of programmed cell death, which is in agreement with the internucleosomal fragmentation of P40-treated cell DNA as shown by agarose gel electrophoresis. We showed that (125)I-radiolabeled or fluorescein isothiocyanate-labeled P40 was able to bind specifically in a dose-dependent manner to the cell membrane of CEM cells, which suggested that the cytotoxicity of P40 endonuclease was mediated by its interaction with the cell surface receptor(s). The concentration of unlabeled P40 required to inhibit by 50% the formation of (125)I-P40-CEM complexes was about 3 x 10(-9) M, indicating a high-affinity interaction. Both P40 interaction and cytotoxicity are Ca(2+) dependent. Our results suggest that the cytotoxicity of M. penetrans observed in vitro is mediated at least partially by secreted P40, which, after interaction with host cells, can induce an apoptosis-like death. These results strongly suggest a major role of mycoplasmal nucleases as potential pathogenic determinants.

Mycoplasma penetrans and other mycoplasmas in urine of human immunodeficiency virus-positive children

Urine samples from children with human immunodeficiency virus (HIV) infection and healthy controls were examined for mycoplasmas by culture. Standard biochemical assays, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and PCR (16S and 16S-23S spacer rRNA region) were used for identification of isolates. Mycoplasmas were identified from 13 (87%) of 15 HIV-positive patients and 3 (20%) of 15 HIV-negative control patients. The frequency and type of mycoplasma varied with the severity of HIV infection. Mycoplasma penetrans, Mycoplasma pirum, Mycoplasma fermentans, and Mycoplasma genitalium were isolated from patients with severe immunodeficiency. Mycoplasma hominis and Ureaplasma urealyticum were isolated more frequently from children in the early stages of HIV infection and from HIV-negative patients. Mycoplasma penetrans was isolated from one (50%) of two patients in Centers for Disease Control and Prevention (CDC) group B and from five (55.5%) of nine pediatric patients with AIDS (CDC group C). This is the first report that indicates that "AIDS-associated" mycoplasmas are more common in HIV-infected children than in HIV-negative controls.

Phase variations of the Mycoplasma penetrans main surface lipoprotein increase antigenic diversity

Mycoplasma penetrans is a recently identified mycoplasma, isolated from urine samples collected from human immunodeficiency virus (HIV)-infected patients. Its presence is significantly associated with HIV infection. The major antigen recognized during natural and experimental infections is an abundant P35 lipoprotein which, upon extraction, segregates in the Triton X-114 detergent phase and is the basis of M. penetrans-specific serological assays. We report here that the P35 antigen undergoes spontaneous and reversible phase variation at high frequency, leading to heterogeneous populations of mycoplasmas, even when derived from a clonal lineage. This variation was found to be determined at the transcription level, and although this property is not unique among the members of the class Mollicutes, the mechanism by which it occurs in M. penetrans differs from those previously described for other Mycoplasma species. Indeed, the P35 phase variation was due neither to a p35 gene rearrangement nor to point mutations within the gene itself or its promoter. The P35 phase variation in the different variants obtained was concomitant with modifications in the pattern of other expressed lipoproteins, probably due to regulated expression of selected members of a gene family which was found to potentially encode similar lipoproteins. M. penetrans variants could be selected on the basis of their lack of colony immunoreactivity with a polyclonal antiserum against a Triton X-114 extract, strongly suggesting that the mechanisms involved in altering surface antigen expression might allow evasion of the humoral immune response of the infected host.

Mycoplasma penetrans bacteremia and primary antiphospholipid syndrome

Mycoplasma penetrans, a rare bacterium so far only found in HIV-infected persons, was isolated in the blood and throat of a non-HIV-infected patient with primary antiphospholipid syndrome (whose etiology and pathogenesis are unknown).

Molecular biology and pathogenicity of mycoplasmas

The recent sequencing of the entire genomes of Mycoplasma genitalium and M. pneumoniae has attracted considerable attention to the molecular biology of mycoplasmas, the smallest self-replicating organisms. It appears that we are now much closer to the goal of defining, in molecular terms, the entire machinery of a self-replicating cell. Comparative genomics based on comparison of the genomic makeup of mycoplasmal genomes with those of other bacteria, has opened new ways of looking at the evolutionary history of the mycoplasmas. There is now solid genetic support for the hypothesis that mycoplasmas have evolved as a branch of gram-positive bacteria by a process of reductive evolution. During this process, the mycoplasmas lost considerable portions of their ancestors' chromosomes but retained the genes essential for life. Thus, the mycoplasmal genomes carry a high percentage of conserved genes, greatly facilitating gene annotation. The significant genome compaction that occurred in mycoplasmas was made possible by adopting a parasitic mode of life. The supply of nutrients from their hosts apparently enabled mycoplasmas to lose, during evolution, the genes for many assimilative processes. During their evolution and adaptation to a parasitic mode of life, the mycoplasmas have developed various genetic systems providing a highly plastic set of variable surface proteins to evade the host immune system. The uniqueness of the mycoplasmal systems is manifested by the presence of highly mutable modules combined with an ability to expand the antigenic repertoire by generating structural alternatives, all compressed into limited genomic sequences. In the absence of a cell wall and a periplasmic space, the majority of surface variable antigens in mycoplasmas are lipoproteins. Apart from providing specific antimycoplasmal defense, the host immune system is also involved in the development of pathogenic lesions and exacerbation of mycoplasma induced diseases. Mycoplasmas are able to stimulate as well as suppress lymphocytes in a nonspecific, polyclonal manner, both in vitro and in vivo. As well as to affecting various subsets of lymphocytes, mycoplasmas and mycoplasma-derived cell components modulate the activities of monocytes/macrophages and NK cells and trigger the production of a wide variety of up-regulating and down-regulating cytokines and chemokines. Mycoplasma-mediated secretion of proinflammatory cytokines, such as tumor necrosis factor alpha, interleukin-1 (IL-1), and IL-6, by macrophages and of up-regulating cytokines by mitogenically stimulated lymphocytes plays a major role in mycoplasma-induced immune system modulation and inflammatory responses.

Modulation of lympho-proliferative responses of ovine peripheral blood mononuclear cells by Mycoplasma mycoides ssp. mycoides (LC type)

The present study was carried out to investigate the immunomodulating potential of M. mycoides ssp. mycoides (Mmm) (LC): a standard strain (Y-Goat, YG) and a local strain (M30) isolated from the pneumonic lung of a lamb during an outbreak of respiratory disease. The study was conducted in two parts to determine in vitro and in vivo aspects of the Mmm-induced modulation of cellular immune responses. In vitro experiments, using peripheral blood mononuclear cells (PBMC) of naive lambs, showed that live (Lv) or inactivated (Ina) antigens of Mmm (strains YG and M30) were not mitogenic for PBMC. Live antigens of both the strains, however, induced significant suppression of the PHA-driven lympho-proliferative (LP) responses. Suppression of LP responses by infectious Mmm (both strains) was restored in the presence of exogenous recombinant human interleukin-2 (rhIL-2). Following experimental inoculation of lambs with Mmm (YG), a significant reduction in non-specific LP responses was observed on days 6, 10 and 14 post inoculation (p.i.). There was a slow but significant rise in memory LP responses to Mmm strains (YG and M30). Specific subset depletion studies, using immunomagnetic cell separation (IMCS) technique, carried out on days 10 and 14 p.i., revealed that the OvCD4+ cell population was the main proliferating lymphocyte subset following an infection with Mmm (LC type).

A longitudinal study of seroreactivity against Mycoplasma penetrans in HIV-infected homosexual men: association with disease progression

We investigated the relationships between a putative cofactor of HIV infection, Mycoplasma penetrans, and the evolution of HIV disease. The evolution of titers of anti-M. penetrans antibodies in 58 randomly selected HIV-seropositive adult homosexual men was investigated. The median length of follow-up was 38 months. Thirty-six individuals was investigated. The median length of follow-up was 38 months. Thirty-six individuals (62.1%) remained M. penetrans seronegative (group 0). Fourteen patients (24.1%) had consistently low antibody titers or low antibody titer(s) in at least one sample and negative test(s) in the other(s). This pattern was possibly associated with latent or earlier infection (group 1). Eight patients (13.8%) had moderate to high antibody titers for long periods, indicating an active and persistent M. penetrans infection (group 2); four patients in this group presented a serological reactivation and thus probably developed an acute infection during the study; two had a stable and moderate level of antibody throughout the study; in two patients the antibody titers decreased substantially. Interestingly, CD4 cell counts declined more rapidly in group 2 than in group 0 (medians of -4.5 versus -2.1 cells/mm3/month, p < 0.05 and -0.16 versus 0 cell percentage/month, p < 0.05), whereas there was no significant difference between groups 1 and 0 (medians of -2.0 versus -2.1 cells/mm3/month and -0.15 versus 0 cell percentage/month). In patients with serological reactivation, the viral load was higher in sera with higher M. penetrans antibody titers. These findings suggest an association between active M. penetrans infection and progression of HIV disease.

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.

Immunologic cross-reaction between HIV type 1 p17 and Mycoplasma hyorhinis variable lipoprotein

Monoclonal antibodies directed against the HIV-1 matrix protein p17 that react with a component present on the surface of HIV-1-infected cells have previously been described. In this study we show that one of these monoclonal antibodies binds to persistently HIV-1-infected cell lines that are coinfected with Mycoplasma hyorhinis, but not to cell lines that are uninfected with mycoplasma. Mycoplasma-infected cells secrete HIV-1 at a higher rate, have a slight increase in cell surface expression of gp120 and gp41, and are less sensitive to immunotoxins than uninfected cells. The anti-p17 antibody binds to a protein of M. hyorhinis grown in cell-free culture. The variable expression and size of the protein among strains is typical of the variable lipoprotein (Vlp) system of M. hyorhinis. Confirmation of the reactivity of the antibody with a Vlp was provided by demonstrating its specific binding to recombinant VlpF expressed in E. coli, and to a synthetic peptide representing the carboxy-terminal region of VlpF, but not to other recombinant Vlp products or peptides. This is a true cross-reaction because the antibody also binds to recombinant p17 expressed in E. coli and the binding is inhibited by the VlpF peptide. These analyses highlight the potential of mycoplasma contamination of tissue culture cell lines to cause anomalous results. With regard to HIV-1, mycoplasma infection of cells results in increased rates of virus secretion, and introduces a potential confounding immunologic cross-reaction as well. The existence of a cell surface form of p17 is unlikely.

Detection of mycoplasmas in urethral swabs from HIV-1 infected patients and control individuals using culture techniques and polymerase chain reaction

The objective of the present study was to determine the prevalence of certain mycoplasma species, i.e., Mycoplasma hominis, Ureaplasma urealyticum and Mycoplasma penetrans, in urethral swabs from HIV-1 infected patients compared to swabs from a control group. Mycoplasmas were detected by routine culture techniques and by the Polymerase Chain Reaction (PCR) technique, using 16SrRNA generic primers of conserved region and Mycoplasma penetrans specific primers. The positivity rates obtained with the two methods were comparable. Nevertheless, PCR was more sensitive, while the culture techniques allowed the quantification of the isolates. The results showed no significant difference (p < 0.05) in positivity rates between the methods used for mycoplasma detection.

Antibodies to mycoplasma fermentans in HIV-positive heterosexual patients: seroprevalence and association with AIDS

There are conflicting reports concerning the prevalence of Mycoplasma fermentans in HIV-positive patients and its association with AIDS. Serum antibodies to M. fermentans were measured by a modified immunoblotting technique in 48 HIV-positive heterosexual patients and in 30 HIV-negative heterosexual controls. Antibodies to M. fermentans were detected in 19 (40%) of HIV-positive patients and in three (10%) of the HIV-negative controls (P = 0.01). The prevalence of antibodies to Mycoplasma hominis and to Ureaplasma urealyticum was similar in both groups. In the HIV-positive group, 16/19 (84%) M. fermentans-positive patients developed AIDS, compared to eight of 29 (28%) M. fermentans-negative patients (P = 0.0004). The HIV-positive patients with antibodies to M. fermentans had a lower CD4+ cell count and a higher prevalence of antibodies to the other mycoplasma tested (P = 0.007 and P = 0.03, respectively), as compared to the patients without antibodies to M. fermentans. These findings may suggest that the presence of antibodies to M. fermentans indicate an opportunistic infection. Of the 19 M. fermentans-positive patients, 11 were positive on the first examination, and eight became positive during the follow-up period. Seven out of these eight patients developed antibodies to M. fermentans before the development of AIDS. Therefore, the possibility exists that M. fermentans might influence the development of AIDS.

High prevalence of antibodies to Mycoplasma penetrans in human immunodeficiency virus-seronegative and -seropositive populations in Brazzaville, Congo

In industrialized countries, the prevalence of antibodies to Mycoplasma penetrans is higher among human immunodeficiency virus (HIV)-seropositive homosexuals than other HIV-seropositive and HIV-seronegative groups. In an African heterosexual population, we found a higher prevalence of M. penetrans antibodies in HIV-seronegative blood donors (15.5%) than in France (0.9%) or the United States (0.3%) and a prevalence of 13.4% in HIV-seropositive individuals. HIV-seropositive individuals with less than 5% CD4 cells had a higher prevalence of M. penetrans antibodies than individuals with 5% or more CD4 cells (25.0 versus 8.5%).

Influence of microbial infections on the progression of HIV disease

HIV infection is associated with immune activation, which in turn stimulates HIV replication. Certain other co-infections cause immune activation and may contribute to an increased viral load. The impact of co-infections by microorganisms such as Mycobacterium tuberculosis can be important for patient survival, particularly those at high risk of exposure to infection and with poor access to medical care.

Purification and characterization of Mycoplasma penetrans Ca2+/Mg2+-dependent endonuclease

The major nuclease from Mycoplasma penetrans has been purified to homogeneity. The enzyme seems to be present as a membrane-associated precursor of 50 kDa and as a peripheral membrane monomeric polypeptide of 40 kDa that is easily removed by washing of cells with isotonic buffers and in the aqueous phase upon Triton partitioning of Triton X-114-solubilized protein. The 40-kDa nuclease was extracted from M. penetrans cells by Triton X-114 and phase fractionation and was further purified by chromatography on Superdex 75 and chelating Sepharose (Zn2+ form) columns. By gel filtration, the apparent molecular mass was 40 kDa. The purified enzyme exhibits both a nicking activity on superhelical and linear double-stranded DNA and a nuclease activity on RNA and single-stranded DNA. No exonuclease activity was found for this enzyme. This nuclease required both Mg2+ (optimum, 5 mM) and Ca2+ (optimum, 2 mM) for activity and exhibited a pH optimum between pH 7 and 8 for DNase activity. It was inhibited by Zn2+, Mn2+, heparin, sodium dodecyl sulfate, and chelator agents such EDTA and EGTA, but no effect was observed with ATP, 2-mercaptoethanol, N-ethylmaleimide, dithiothreitol, nonionic detergents, phenylmethylsulfonyl fluoride, and iodoacetamide. Nuclease activity was inhibited by diethylpyrocarbonate at both pH 6 and 8 and by pepstatin, suggesting the involvement of a histidine and an aspartate in the active site. When added to human lymphoblast nuclei, the purified M. penetrans endonuclease induced internucleosomal fragmentation of the chomatin into oligonucleosomal fragments. On the basis of this result, and taking into account the fact that M. penetrans has the capacity to invade eucaryotic cells, one can suggest, but not assert, that produced Ca2+/Mg2+-dependent endonuclease may alter the nucleic acid metabolism of host cells by DNA and/or RNA degradation and may act as a potential pathogenic determinant.

Mycoplasmas: sophisticated, reemerging, and burdened by their notoriety

Mycoplasmas are most unusual self-replicating bacteria, possessing very small genomes, lacking cell wall components, requiring cholesterol for membrane function and growth, using UGA codon for tryptophan, passing through "bacterial-retaining" filters, and displaying genetic economy that requires a strict dependence on the host for nutrients and refuge. In addition, many of the mycoplasmas pathogenic for humans and animals possess extraordinary specialized tip organelles that mediate their intimate interaction with eucaryotic cells. This host-adapted survival is achieved through surface parasitism of target cells, acquisition of essential biosynthetic precursors, and in some cases, subsequent entry and survival intracellularly. Misconceptions concerning the role of mycoplasmas in disease pathogenesis can be directly attributed to their biological subtleties and to fundamental deficits in understanding their virulence capabilities. In this review, we highlight the biology and pathogenesis of these procaryotes and provide new evidence that may lead to increased appreciation of their role as human pathogens.

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.

Induction of tumor necrosis factor alpha (TNF alpha) and enhancement of HIV-1 replication in the J22HL60 cell line by Mycoplasma penetrans

Mycoplasma penetrans isolated from clinical specimens of AIDS patients showed potent activity in tumor necrosis factor alpha (TNF alpha) production in THP-1, U937 and J22HL60 cell lines, and in the enhancement of HIV-1 replication in a dormantly-infected J22HL60 cell line as compared with the activities of other mycoplasmas. Both activities were found in the methanol layer but not in the chloroform layer of the membrane extracted by the Bligh-Dyer method. TNF alpha production was observed in the peritoneal macrophages from both lipopolysaccharide-responsive and -unresponsive mouse strains, and was not inhibited by polymyxin B. The induction of TNF alpha production and enhancement of HIV-1 replication were strongly inhibited by Concanavalin A-Sepharose. The inhibitory effect of Concanavalin A-Sepharose was partially prevented by sugars in the order methyl-alpha-D-mannopyranoside and methyl-alpha-D-glucopyranoside but not methyl-alpha-D-galactopyranoside. Anti-human TNF alpha antibody, however, did not reduce the activity of the methanol layer to enhance HIV-1 replication, suggesting that the methanol layer could enhance HIV-1 replication directly. These results suggest that the carbohydrate derived from M. penetrans might be responsible for the progression of HIV-1 infection.

In vitro influence of Mycoplasma penetrans on activation of peripheral T lymphocytes from healthy donors or human immunodeficiency virus-infected individuals

Mycoplasma penetrans is a mycoplasma species newly isolated from the urine of human immunodeficiency virus (HIV)-infected individuals and presents the only case in which an association has been found between antibodies against a mycoplasma and HIV infection. To further explore the effects of M. penetrans on the immune system, we studied the influence of this mycoplasma on peripheral blood mononuclear cells (PBMCs) from healthy donors and HIV-infected individuals. M. penetrans induced, in addition to blastogenesis of PBMCs, a significant proliferative response associated with the expression of some activation markers such as CD69, HLA-DR, and CD25. This M. penetrans-dependent lymphocyte activation was observed not only in healthy donors but also in HIV-infected persons at different stages of the disease. In addition, our study revealed that both CD4+ and CD8+ T lymphocytes were responsive to M. penetrans. Interestingly, the mitogenic activity of M. penetrans was associated with mycoplasma cells but not with the supernatants of mycoplasma culture. The potent stimulating activity of M. penetrans on T lymphocytes from HIV-infected individuals is of particular interest in view of the supposed contribution of immune activation to HIV replication and disease progression.

Characterization of a major Mycoplasma penetrans lipoprotein and of its gene

A novel mycoplasmal species designated as Mycoplasma penetrans has been isolated recently from patients infected with human immunodeficiency virus. p35, a major antigen extracted from the membrane of this mycoplasma using Triton X-114 has been found to be a lipoprotein. After proteolytic treatment of p35, the sequence of one of the resulting peptides was determined and a corresponding oligonucleotide was deduced. Using this oligonucleotide as a probe the p35 gene was cloned and sequenced. Sequence analysis revealed an amino-terminal signal peptide with a potential acylation site which would result in a 35.3 kDa mature product. In addition, the p35 gene was followed by an open reading frame with a corresponding polypeptide partially homologous to p35, in particular to the N-terminus region.