Biology of trichomonosis

Synergistic effect of compounds directed to triosephosphate isomerase, a combination to develop drug against trichomoniasis

The development of new drugs is continuous in the world; currently, saving resources (both economic ones and time) and preventing secondary effects have become a necessity for drug developers. Trichomoniasis is the most common nonviral sexually transmitted infection affecting more than 270 million people around the world. In our research group, we focussed on developing a selective and more effective drug against Trichomonas vaginalis, and we previously reported on a compound, called A4, which had a trichomonacidal effect. Later, we determined another compound, called D4, which also had a trichomonacidal effect together with favorable toxicity results. Both A4 and D4 are directed at the enzyme triosephosphate isomerase. Thus, we made combinations between the two compounds, in which we determined a synergistic effect against T. vaginalis, determining the IC₅₀ and the toxicity of the best relationship to obtain the trichomonacidal effect. With these results, we can propose a combination of compounds that represents a promising alternative for the development of a new therapeutic strategy against trichomoniasis.

Triosephosphate isomerase as a therapeutic target against trichomoniasis

Trichomoniasis is the most common non-viral sexually transmitted infection, caused by the protozoan parasite Trichomonas vaginalis, affecting millions of people worldwide. The main treatment against trichomoniasis is metronidazole and other nitroimidazole derivatives, but up to twenty percent of clinical cases of trichomoniasis are resistant to these drugs. In this study, we used high-performance virtual screening to search for molecules that specifically bind to the protein, triosephosphate isomerase from T. vaginalis (TvTIM). By in silico molecular docking analysis, we selected six compounds from a chemical library of almost 500,000 compounds. While none of the six inhibited the enzymatic activity of recombinant triosephosphate isomerase isoforms, one compound (A4; 3,3'-{[4-(4-morpholinyl)phenyl]methylene}bis(4- hydroxy-2H-chromen-2-one) altered their fluorescence emission spectra, suggesting that this chemical might interfere in an important non-glycolytic function of TvTIM. In vitro assays demonstrate that A4 is not cytotoxic but does have trichomonacidal impact on T. vaginalis cultures. With these results, we propose this compound as a potential drug with a new therapeutic target against Trichomonas vaginalis.

The Role of Purinergic Signaling in Trichomonas vaginalis Infection

Trichomoniasis, one of the most common non-viral sexually transmitted infections worldwide, is caused by the parasite Trichomonas vaginalis. The pathogen colonizes the human urogenital tract, and the infection is associated with complications such as adverse pregnancy outcomes, cervical cancer, and an increase in HIV transmission. The mechanisms of pathogenicity are multifactorial, and controlling immune responses is essential for infection maintenance. Extracellular purine nucleotides are released by cells in physiological and pathological conditions, and they are hydrolyzed by enzymes called ecto-nucleotidases. The cellular effects of nucleotides and nucleosides occur via binding to purinoceptors, or through the uptake by nucleoside transporters. Altogether, enzymes, receptors and transporters constitute the purinergic signaling, a cellular network that regulates several effects in practically all systems including mammals, helminths, protozoa, bacteria, and fungi. In this context, this review updates the data on purinergic signaling involved in T. vaginalis biology and interaction with host cells, focusing on the characterization of ecto-nucleotidases and on purine salvage pathways. The implications of the final products, the nucleosides adenosine and guanosine, for human neutrophil response and vaginal epithelial cell damage reveal the purinergic signaling as a potential new mechanism for alternative drug targets.

The effect of iron on Trichomonas vaginalis TvCP2: a cysteine proteinase found in vaginal secretions of trichomoniasis patients

Trichomonas vaginalis (Tv) induces host cell damage through cysteine proteinases (CPs) modulated by iron. An immunoproteomic analysis showed that trichomoniasis patient sera recognize various CPs, also some of them are present in vaginal washes (VWs). Thus, the goal of this work was to determine whether TvCP2 is expressed during infection and to assess the effect of iron on TvCP2 expression, localization and contribution to in vitro cellular damage. Western-blotting (WB) assays using TvCP2r and vaginitis patient serum samples showed that 6/9 Tv (+) but none of the Tv (-) patient sera recognized TvCP2r. WB using an anti-TvCP2r antibody and VWs from the same patients showed that in all of the Tv (+) but none of the Tv (-) VWs, the anti-TvCP2r antibody detected a 27 kDa protein band that corresponded to the mature TvCP2, which was confirmed by mass spectrometry analysis. Iron decreased the amount of TvCP2 mRNA and the protein localized on the parasite surface and cytoplasmic vesicles concomitant with the cytotoxic effect of TvCP2 on HeLa cells. Parasites pretreated with the anti-TvCP2r antibody also showed reduced levels of cytotoxicity and apoptosis induction in HeLa cell monolayers. In conclusion, these results show that TvCP2 is expressed during trichomonal infection and plays an important role in the in vitro HeLa cell cytotoxic damage under iron-restricted conditions.

Immunopathology of Recurrent Vulvovaginal Infections: New Aspects and Research Directions

Recurrent vulvovaginal infections (RVVI), a devastating group of mucosal infection, are severely affecting women's quality of life. Our understanding of the vaginal defense mechanisms have broadened recently with studies uncovering the inflammatory nature of bacterial vaginosis, inflammatory responses against novel virulence factors, innate Type 17 cells/IL-17 axis, neutrophils mediated killing of pathogens by a novel mechanism, and oxidative stress during vaginal infections. However, the pathogens have fine mechanisms to subvert or manipulate the host immune responses, hijack them and use them for their own advantage. The odds of hijacking increases, due to impaired immune responses, the net magnitude of which is the result of numerous genetic variations, present in multiple host genes, detailed in this review. Thus, by underlining the role of the host immune responses in disease etiology, modern research has clarified a major hypothesis shift in the pathophilosophy of RVVI. This knowledge can further be used to develop efficient immune-based diagnosis and treatment strategies for this enigmatic disease conditions. As for instance, plasma-derived MBL replacement, adoptive T-cell, and antibody-based therapies have been reported to be safe and efficacious in infectious diseases. Therefore, these emerging immune-therapies could possibly be the future therapeutic options for RVVI.

Epigenome mapping highlights chromatin-mediated gene regulation in the protozoan parasite Trichomonas vaginalis

Trichomonas vaginalis is an extracellular flagellated protozoan parasite that causes trichomoniasis, one of the most common non-viral sexually transmitted diseases. To survive and to maintain infection, T. vaginalis adapts to a hostile host environment by regulating gene expression. However, the mechanisms of transcriptional regulation are poorly understood for this parasite. Histone modification has a marked effect on chromatin structure and directs the recruitment of transcriptional machinery, thereby regulating essential cellular processes. In this study, we aimed to outline modes of chromatin-mediated gene regulation in T. vaginalis. Inhibition of histone deacetylase (HDAC) alters global transcriptional responses and induces hyperacetylation of histones and hypermethylation of H3K4. Analysis of the genome of T. vaginalis revealed that a number of enzymes regulate histone modification, suggesting that epigenetic mechanisms are important to controlling gene expression in this organism. Additionally, we describe the genome-wide localization of two histone H3 modifications (H3K4me3 and H3K27Ac), which we found to be positively associated with active gene expression in both steady and dynamic transcriptional states. These results provide the first direct evidence that histone modifications play an essential role in transcriptional regulation of T. vaginalis, and may help guide future epigenetic research into therapeutic intervention strategies against this parasite.

Trichomoniasis immunity and the involvement of the purinergic signaling

Innate and adaptive immunity play a significant role in trichomoniasis, the most common non-viral sexually transmitted disease worldwide. In the urogenital tract, innate immunity is accomplished by a defense physical barrier constituted by epithelial cells, mucus, and acidic pH. During infection, immune cells, antimicrobial peptides, cytokines, chemokines, and adaptive immunity evolve in the reproductive tract, and a proinflammatory response is generated to eliminate the invading extracellular pathogen Trichomonas vaginalis. However, the parasite has developed complex evolutionary mechanisms to evade the host immune response through cysteine proteases, phenotypic variation, and molecular mimicry. The purinergic system constitutes a signaling cellular net where nucleotides and nucleosides, enzymes, purinoceptors and transporters are involved in almost all cells and tissues signaling pathways, especially in central and autonomic nervous systems, endocrine, respiratory, cardiac, reproductive, and immune systems, during physiological as well as pathological processes. The involvement of the purinergic system in T. vaginalis biology and infection has been demonstrated and this review highlights the participation of this signaling pathway in the parasite immune evasion strategies.

The Glycolytic Enzyme Triosephosphate Isomerase of Trichomonas vaginalis Is a Surface-Associated Protein Induced by Glucose That Functions as a Laminin- and Fibronectin-Binding Protein

Triosephosphate isomerase of Trichomonas vaginalis (TvTIM) is a 27-kDa cytoplasmic protein encoded by two genes, tvtim1 and tvtim2, that participates in glucose metabolism. TvTIM is also localized to the parasite surface. Thus, the goal of this study was to identify the novel functions of the surface-associated TvTIM in T. vaginalis and to assess the effect of glucose as an environmental factor that regulates its expression and localization. Reverse transcription-PCR (RT-PCR) showed that the tvtim genes were differentially expressed in response to glucose concentration. tvtim1 was overexpressed under glucose-restricted (GR) conditions, whereas tvtim2 was overexpressed under glucose-rich, or high-glucose (HG), conditions. Western blot and indirect immunofluorescence assays also showed that glucose positively affected the amount and surface localization of TvTIM in T. vaginalis Affinity ligand assays demonstrated that the recombinant TvTIM1 and TvTIM2 proteins bound to laminin (Lm) and fibronectin (Fn) but not to plasminogen. Moreover, higher levels of adherence to Lm and Fn were detected in parasites grown under HG conditions than in those grown under GR conditions. Furthermore, pretreatment of trichomonads with an anti-TvTIMr polyclonal antibody or pretreatment of Lm- or Fn-coated wells with both recombinant proteins (TvTIM1r and TvTIM2r) specifically reduced the binding of live parasites to Lm and Fn in a concentration-dependent manner. Moreover, T. vaginalis was exposed to different glucose concentrations during vaginal infection of women with trichomoniasis. Our data indicate that TvTIM is a surface-associated protein under HG conditions that mediates specific binding to Lm and Fn as a novel virulence factor of T. vaginalis.

Activity of pyrrolizidine alkaloids against biofilm formation and Trichomonas vaginalis

Crotalaria genus belongs to the subfamily Papilionoideae comprising about 600 species spread throughout tropical, neotropical and subtropical regions. In this study, seeds of Crolatalaria pallida were used to the isolation of usaramine, a pyrrolizidine alkaloid. Thus, Pseudomonas aeruginosa and Staphylococcus epidermidis were utilized as strains to test some activities of this alkaloid, such as antibiofilm and antibacterial. Meanwhile, monocrotaline obtained from Crotalaria retusa seeds, was used as the starting material for synthesis of necine base derivatives with anti-Trichomonas vaginalis potential. Alkaloids were characterized by 1D and 2D NMR techniques and GC-MS analysis. Usaramine demonstrated a highlighted antibiofilm activity against S. epidermidis by reducing more than 50% of biofilm formation without killing the bacteria, thus it could be assumed as a prototype for the development of new antibiofilm molecules for pharmaceutical and industrial purposes. Monocrotaline activity against T. vaginalis was evaluated and results indicated inhibition of 80% on parasite growth at 1mg/mL, in addition, neither cytotoxicity against vaginal epithelial cells nor hemolytic activity were observed. On the other hand, retronecine showed no anti-T. vaginalis activity while azido-retronecine was more active than monocrotaline killing 85% of the parasites at 1mg/mL. In conclusion, pyrrolizidine alkaloids are suggested as promising prototypes for new drugs especially for topical use.

Trichomoniasis - are we giving the deserved attention to the most common non-viral sexually transmitted disease worldwide?

ETIOLOGY

Trichomonas vaginalis is the etiologic agent of trichomoniasis, the most common non-viral sexually transmitted disease (STD) in the world. Transmission: Trichomoniasis is transmitted by sexual intercourse and transmission via fomites is rare. Epidemiology, incidence and prevalence: The WHO estimates an incidence of 276 million new cases each year and prevalence of 187 million of infected individuals. However, the infection is not notifiable. Pathology/Symptomatology: The T. vaginalis infection results in a variety of clinical manifestations - in most cases the patients are asymptomatic, but some may develop signs typically associated to the disease. Importantly, the main issue concerning trichomoniasis is its relationship with serious health consequences such as cancer, adverse pregnancy outcomes, infertility, and HIV acquisition. Molecular mechanisms of infection: To achieve success in parasitism trichomonads develop a complex process against the host cells that includes dependent- and independent-contact mechanisms. This multifactorial pathogenesis includes molecules such as soluble factors, secreted proteinases, adhesins, lipophosphoglycan that culminate in cytoadherence and cytotoxicity against the host cells. Treatment and curability: The treatment with metronidazole or tinidazole is recommended; however, cure failures remain problematic due to noncompliance, reinfection and/or lack of treatment of sexual partners, inaccurate diagnosis, or drug resistance. Therefore, new therapeutic alternatives are urgently needed. Protection: Strategies for protection including sexual behavior, condom usage, and therapy have not contributed to the decrease on disease prevalence, pointing to the need for innovative approaches. Vaccine development has been hampered by the lack of long-lasting humoral immunity associated to the absence of good animal models.

Trichomonas vaginalis: An Updated Overview Towards Diagnostic Improvement

The protozoan Trichomonas vaginalis (TV) is responsible for trichomonosis, a sexually transmitted disease (STD) with a significant incidence worldwide. This infection is one of the most common non-viral STDs, representing almost 50% of all curable STDs. Trichomonosis has an incidence of 180 million new cases worldwide. Nowadays, the 'gold standard' for TV diagnosis remains the use of in vitro cultures combined with daily visual microscopic evaluations, which is a time-consuming and low sensitive method. Recent diagnostic methodologies include imunocromatographic assays and molecular biology techniques. The use of the latter has improved enormously the sensitivity and specificity of TV diagnosis, despite, however, none being unable to identify the presence of live parasites. By understanding the biology, the pathogenesis, the proteomic profile and its relation with the parasite's virulence mechanisms, new possibilities towards diagnostic techniques can arise. This review covers various important aspects of vaginal trichomonosis from the parasite's biology and virulence to recent improvements in diagnostic techniques and also metabolic and protein discoveries.

RNA-Binding Proteins in Trichomonas vaginalis: Atypical Multifunctional Proteins

Iron homeostasis is highly regulated in vertebrates through a regulatory system mediated by RNA-protein interactions between the iron regulatory proteins (IRPs) that interact with an iron responsive element (IRE) located in certain mRNAs, dubbed the IRE-IRP regulatory system. Trichomonas vaginalis, the causal agent of trichomoniasis, presents high iron dependency to regulate its growth, metabolism, and virulence properties. Although T. vaginalis lacks IRPs or proteins with aconitase activity, possesses gene expression mechanisms of iron regulation at the transcriptional and posttranscriptional levels. However, only one gene with iron regulation at the transcriptional level has been described. Recently, our research group described an iron posttranscriptional regulatory mechanism in the T. vaginalis tvcp4 and tvcp12 cysteine proteinase mRNAs. The tvcp4 and tvcp12 mRNAs have a stem-loop structure in the 5'-coding region or in the 3'-UTR, respectively that interacts with T. vaginalis multifunctional proteins HSP70, α-Actinin, and Actin under iron starvation condition, causing translation inhibition or mRNA stabilization similar to the previously characterized IRE-IRP system in eukaryotes. Herein, we summarize recent progress and shed some light on atypical RNA-binding proteins that may participate in the iron posttranscriptional regulation in T. vaginalis.

New strategies for local treatment of vaginal infections

Vaginal infections are extremely prevalent, particularly among women of reproductive age. Although they do not result in high mortality rates, these infections are associated with high levels of anxiety and reduction of quality of life. In most cases, topical treatment of vaginal infections has been shown to be at least as effective as oral treatment, resulting in higher local drug concentrations, with fewer drug interactions and adverse effects. Furthermore, the emergence of microbial resistance to chemotherapeutics and the difficulties in managing infection recurrences sustain the need for more effective local treatments. However, conventional dosage forms have been associated with low retention in the vagina and discomfort. Formulation strategies such as the development of bioadhesive, thermogelling systems and microtechnological or nanotechnological approaches have been proposed to improve delivery of traditional drugs, and other treatment modalities such as new drugs, plant extracts, and probiotics are being studied. This article reviews the recent strategies studied to improve the treatment and prevention of the commonest vaginal infections-namely, vaginal bacteriosis, aerobic vaginitis, vulvovaginal candidosis, and trichomoniasis-through the intravaginal route.

Trichomonas vaginalis Cysteine Proteinases: Iron Response in Gene Expression and Proteolytic Activity

We focus on the iron response of Trichomonas vaginalis to gene family products such as the cysteine proteinases (CPs) involved in virulence properties. In particular, we examined the effect of iron on the gene expression regulation and function of cathepsin L-like and asparaginyl endopeptidase-like CPs as virulence factors. We addressed some important aspects about CPs genomic organization and we offer possible explanations to the fact that only few members of this large gene family are expressed at the RNA and protein levels and the way to control their proteolytic activity. We also summarized all known iron regulations of CPs at transcriptional, posttranscriptional, and posttranslational levels along with new insights into the possible epigenetic and miRNA processes.

Biological roles of cysteine proteinases in the pathogenesis of Trichomonas vaginalis

Human trichomonosis, infection with Trichomonas vaginalis, is the most common non-viral sexually transmitted disease in the world. The host-parasite interaction and pathophysiological processes of trichomonosis remain incompletely understood. This review focuses on the advancements reached in the area of the pathogenesis of T. vaginalis, especially in the role of the cysteine proteinases. It highlights various approaches made in this field and lists a group of trichomonad cysteine proteinases involved in diverse processes such as invasion of the mucous layer, cytoadherence, cytotoxicity, cytoskeleton disruption of red blood cells, hemolysis, and evasion of the host immune response. A better understanding of the biological roles of cysteine proteinases in the pathogenesis of this parasite could be used in the identification of new chemotherapeutic targets. An additional advantage could be the development of a vaccine in order to reduce transmission of T. vaginalis.

Anti-Trichomonas vaginalis activity from triterpenoid derivatives

Trichomonas vaginalis is a flagellated parasite that causes trichomonosis, the most common non-viral sexually transmitted disease (STD) in the world. Worryingly, trichomonosis is associated to increased transmission of HIV. Due to high frequency of the infection during pregnancy and the development of metronidazole-resistant isolates, therapeutic alternatives to 5-nitroimidazole are being searched. Triterpenes are natural products presenting several biological activities such as anti-protozoal activity. The aim of this study was to evaluate the in vitro anti-T. vaginalis activity from betulinic and ursolic acids, as well as semisynthetic derivatives obtained. Compounds obtained from betulinic acid presented better activity than those from ursolic acid. Piperazine derivatived from betulinic acid presented minimum inhibitory concentration (MIC) value of 91.2 μM, and the kinetic growth curve performed with parasites treated with this most active compound revealed complete inhibition of trophozoite proliferation at 2 h of incubation and total abolition of trophozoite growth in 24 h, revealing that the piperazine derivative is an efficient trichomonacidal molecule. The same compound promoted total erythrocyte lysis and lactate dehydrogenase (LDH) liberation of 83 and 100% (at 45.6 and 91.2 μM, respectively), indicating parasite membrane damage. The piperazine derivative demonstrated cytotoxic effect against the HMVII and HeLa cell lineages at the MIC value. This is the first report of semisynthetic triterpenoid derivatives with anti-T. vaginalis activity, revealing the high potential of these compounds as trichomonacidal agents.

Identification, characterization, and synthesis of peptide epitopes and a recombinant six-epitope protein for Trichomonas vaginalis serodiagnosis

There is a need for a rapid, accurate serodiagnostic test useful for both women and men infected by Trichomonas vaginalis, which causes the number one sexually transmitted infection (STI). Women and men exposed to T. vaginalis make serum antibody to fructose-1,6-bisphosphate aldolase (ALD), α-enolase (ENO), and glyceraldehyde-3-phosphate dehydrogenase (GAP). We identified, by epitope mapping, the common and distinct epitopes of each protein detected by the sera of women patients with trichomonosis and by the sera of men highly seropositive to the immunogenic protein α-actinin (positive control sera). We analyzed the amino acid sequences to determine the extent of identity of the epitopes of each protein with other proteins in the databanks. This approach identified epitopes unique to T. vaginalis, indicating these peptide-epitopes as possible targets for a serodiagnostic test. Individual or combinations of 15-mer peptide epitopes with low to no identity with other proteins were reactive with positive control sera from both women and men but were unreactive with negative control sera. These analyses permitted the synthesis of a recombinant His₆ fusion protein of 111 amino acids with an M_r of ~13.4 kDa, which consisted of 15-mer peptides of two distinct epitopes each for ALD, ENO, and GAP. This recombinant protein was purified by affinity chromatography. This composite protein was detected by enzyme-linked immunosorbent assay (ELISA), dot blots, and immunoblots, using positive control sera from women and men. These data indicate that it is possible to identify epitopes and that either singly, in combination, or as a composite protein represent targets for a point-of-care serodiagnostic test for T. vaginalis.

IL-22 levels are associated with Trichomonas vaginalis infection in the lower genital tract

PROBLEM

IL-22 has important functions at mucosal surfaces, including the induction of antimicrobial peptides and maintenance of epithelium. However, IL-22 has not been investigated in the genital tract during TV infection.

METHODS OF STUDY

Women who visited an STD clinic and women from a cohort with frequent Trichomoniasis were studied. IL-22, IL-17, and antimicrobial peptides were measured in cervicovaginal lavage by ELISA.

RESULTS

In women visiting the STD clinic, those without STDs (n = 10) had a median IL-22 of 0 pg/mL, while women with infections (n = 30) had 27 pg/mL (P = 0.04). In the cohort, women with Trichomoniasis (n = 19) had significantly higher IL-22 than women with no infections (n = 21, 74 versus 0 pg/mL, P = 0.0001). IL-17 was also significantly increased in Trichomoniasis, and there was a correlation between IL-22 and IL-17 (P = 0.001).

CONCLUSION

IL-22 is increased in STDs generally and in Trichomoniasis specifically suggesting an antimicrobial response of the mucosa and an epithelial repair process induced by the STDs.

Epitopes of the highly immunogenic Trichomonas vaginalis α-actinin are serodiagnostic targets for both women and men

There is a need for a point-of-care serodiagnostic test for women and men for sexually transmitted infections (STIs) caused by Trichomonas vaginalis. Sera from women with this STI and sera from men that were analyzed in studies showing a relationship between serostatus and prostate cancer are highly seropositive in response to trichomonad α-actinin and its truncated protein (ACT-P2) (positive control sera). Epitope mapping experiments showed that positive control sera from women had antibodies to 13 distinct epitopes, 5 of which were detected by positive control sera from men. Sera from women and men that were unreactive with α-actinin (negative control sera) failed to detect any of the epitopes or other α-actinin amino acid sequences. The T. vaginalis α-actinin amino acid sequence and the sequences of the epitopes showed little or no identity with those of other proteins of microbial pathogens or the human α-actinin 1 (HuACTN1) homolog. Immunoassays such as dot blot, immunoblot, and enzyme-linked immunosorbent assays were used. Positive control sera did not detect HuACTN1 in immunoassays, and the range of levels of identity of α-actinin epitopes with HuACTN1 was 0% to 50%. Comparison of the T. vaginalis α-actinin epitopes with proteins in data banks, such as Tritrichomonas suis, Candida albicans, and Saccharomyces cerevisiae proteins, gave a range of identity levels of 0% to 22%. Specific 15-mer peptide epitopes of α-actinin with low to no identity with other proteins were synthesized and were reactive with positive control sera only. These findings identify epitopes of α-actinin as candidate serodiagnostic targets and suggest strongly that a highly seropositive reaction to α-actinin suggests exposure to T. vaginalis.

Analysis of the NTPDase and ecto-5'-nucleotidase profiles in serum-limited Trichomonas vaginalis

Trichomonas vaginalis is a parasite of the human urogenital tract that causes trichomonosis, the most prevalent non-viral sexually transmitted disease. Ectonucleoside triphosphate diphosphohydrolase (NTPDase) family members, which hydrolyse extracellular ATP and ADP and ecto-5'-nucleotidase, which hydrolyses AMP, have been characterised in T. vaginalis. For trichomonad culture, the growth medium is supplemented with 10% serum, which is an important source of nutrients, such as adenosine. Here, we investigated the ATP metabolism of T. vaginalis trophozoites from long-term cultures and clinical isolates under limited bovine serum conditions (1% serum). The specific enzymatic activities were expressed as nmol inorganic phosphate (Pi) released/min/mg protein, the gene expression patterns were determined by reverse transcriptase-polymerase chain reaction, the extracellular adenine nucleotide hydrolysis was analysed by high performance liquid chromatography and the cell cycle analysis was assessed by flow cytometry. Serum limitation led to the profound activation of NTPDase and ecto-5'-nucleotidase activities. Furthermore, the levels of NTPDase A and B transcripts increased and extracellular ATP metabolism was activated, which led to enhanced ATP hydrolysis and the formation of ADP and AMP. Moreover, the cell cycle was arrested at the G0/G1 stage, which suggested adenosine uptake. Our data suggest that under conditions of serum limitation, NTPDase and ecto-5'-nucleotidase play a role in providing the adenosine required for T. vaginalis growth and that this process contributes to the establishment of parasitism.

Prevalência e fatores de risco independentes à tricomoníase em mulheres assistidas na atenção básica

OBJETIVO: Avaliar a prevalência e os fatores associados à tricomoníase em mulheres assistidas na atenção primária. MÉTODOS: Foi desenvolvido um estudo transversal envolvendo uma amostra 314 prontuários, aleatoriamente selecionados por um processo de amostragem sistemática, entre as mulheres atendidas em serviços de atenção básica à saúde. Foram analisadas variáveis socioeconômicas, demográficas e clínicas. RESULTADOS: A prevalência de Trichomonas vaginalis foi de 10,5%, sendo que 35% das mulheres analisadas residiam na zona rural. A análise de regressão logística ajustada mostrou como preditores independentes para a presença da tricomoníase: a elevada pressão arterial, odor vaginal desagradável e dispareunia. CONCLUSÃO: A aplicabilidade prática dos resultados refere-se a subsídios para o planejamento de novas ações de enfermagem para a prevenção e redução da prevalência da tricomoníase em mulheres.

Reversible association of tetraspanin with Trichomonas vaginalis flagella upon adherence to host cells

The parasite Trichomonas vaginalis is the causative agent of trichomoniasis, a prevalent sexually transmitted infection. Here, we report the cellular analyses of T. vaginalis tetraspanin 6 (TvTSP6). This family of membrane proteins has been implicated in cell adhesion, migration and proliferation in vertebrates. We observed that TvTSP6 expression is upregulated upon contact with vaginal ectocervical cells (VECs) and that parasite strains that are highly adherent to VECs express higher levels of TvTSP6 mRNA relative to poorly adherent strains. TvTSP6 is localized predominantly on the flagella of parasites cultured in the absence of host cells; however, adherence of the parasite to VECs initially results in a redistribution of the protein to intracellular vesicles and the plasma membrane of the main body of the cell. We found that a 16-amino-acid C-terminal intracellular tail of TvTSP6 is necessary and sufficient for flagellar localization and protein redistribution when the parasite is in contact with VECs. Additionally, deletion of the C-terminal tail reduced parasite migration through Matrigel, a mimic of the extracellular matrix. Together, our data support roles for TvTSP6 in parasite migration in the host and sensory reception during infection.

Comparative transcriptomic and proteomic analyses of Trichomonas vaginalis following adherence to fibronectin

The morphological transformation of Trichomonas vaginalis from an ellipsoid form in batch culture to an adherent amoeboid form results from the contact of parasites with vaginal epithelial cells and with immobilized fibronectin (FN), a basement membrane component. This suggests host signaling of the parasite. We applied integrated transcriptomic and proteomic approaches to investigate the molecular responses of T. vaginalis upon binding to FN. A transcriptome analysis was performed by using large-scale expressed-sequence-tag (EST) sequencing. A total of 20,704 ESTs generated from batch culture (trophozoite-EST) versus FN-amoeboid trichomonad (FN-EST) cDNA libraries were analyzed. The FN-EST library revealed decreased amounts of transcripts that were of lower abundance in the trophozoite-EST library. There was a shift by FN-bound organisms to the expression of transcripts encoding essential proteins, possibly indicating the expression of genes for adaptation to the morphological changes needed for the FN-adhesive processes. In addition, we identified 43 differentially expressed proteins in the proteomes of FN-bound and unbound trichomonads. Among these proteins, cysteine peptidase, glyceraldehyde-3-phosphate dehydrogenase (an FN-binding protein), and stress-related proteins were upregulated in the FN-adherent cells. Stress-related genes and proteins were highly expressed in both the transcriptome and proteome of FN-bound organisms, implying that these genes and proteins may play critical roles in the response to adherence. This is the first report of a comparative proteomic and transcriptomic analysis after the binding of T. vaginalis to FN. This approach may lead to the discovery of novel virulence genes and affirm the role of genes involved in disease pathogenesis. This knowledge will permit a greater understanding of the complex host-parasite interplay.

The role of bacterial vaginosis and trichomonas in HIV transmission across the female genital tract

Bacterial vaginosis (BV) and Trichomonas vaginalis (TV) infections are both very common and are associated with increased risk of sexual transmission of HIV. There are several mechanisms by which BV and TV could affect susceptibility including inducing pro-inflammatory cytokines and disrupting mucosal barrier function. This review highlights recent advances in our understanding of how these genital conditions lead to an increased risk of HIV infection in women.

Involvement of purinergic signaling on nitric oxide production by neutrophils stimulated with Trichomonas vaginalis

Trichomonas vaginalis is a parasite from the human urogenital tract that causes trichomonosis, the most prevalent non-viral sexually transmitted disease. The neutrophil infiltration has been considered to be primarily responsible for cytological changes observed at infection site, and the chemoattractants can play an important role in this leukocytic recruitment. Nitric oxide (NO) is one of the most widespread mediator compounds, and it is implicated in modulation of immunological mechanisms. Extracellular nucleotides and nucleosides are signaling molecules involved in several processes, including immune responses and control of leukocyte trafficking. Ectonucleoside triphosphate diphosphohydrolase members, ecto-5'-nucleotidase, and adenosine deaminase (ectoADA) have been characterized in T. vaginalis. Herein, we investigated the effects of purinergic system on NO production by neutrophils stimulated with T. vaginalis. The trophozoites were able to induce a high NO synthesis by neutrophils through iNOS pathway. The extracellular nucleotides ATP, ADP, and ATPγS (a non-hydrolyzable ATP analog) showed no significant change in NO secretion. In contrast, adenosine and its degradation product, inosine, promoted a low production of the compound. The immunosuppressive effect of adenosine upon NO release by neutrophils occurred due to adenosine A(2A) receptor activation. The ecto-5'-nucleotidase activity displayed by T. vaginalis was shown to be important in adenosine generation, indicating the efficiency of purinergic cascade. Our data suggest the influence of purinergic signaling, specifically adenosinergic system, on NO production by neutrophils in T. vaginalis infection, contributing to the immunological aspects of disease.

Parasites or cohabitants: cruel omnipresent usurpers or creative "éminences grises"?

This paper presents many types of interplays between parasites and the host, showing the history of parasites, the effects of parasites on the outcome of wars, invasions, migrations, and on the development of numerous regions of the globe, and the impact of parasitic diseases on the society and on the course of human evolution. It also emphasizes the pressing need to change the look at the parasitism phenomenon, proposing that the term “cohabitant” is more accurate than parasite, because every living being, from bacteria to mammals, is a consortium of living beings in the pangenome. Even the term parasitology should be replaced by cohabitology because there is no parasite alone and host alone: both together compose a new adaptive system: the parasitized-host or the cohabitant-cohabited being. It also suggests switching the old paradigm based on attrition and destruction, to a new one founded on adaptation and living together.

Kinetic characterization and gene expression of adenosine deaminase in intact trophozoites of Trichomonas vaginalis

Trichomonas vaginalis is a parasite that resides in the human urogenital tract and causes trichomonosis, the most prevalent nonviral sexually transmitted disease. Nucleoside triphosphate diphosphohydrolase (NTPDase), which hydrolyzes extracellular di- and triphosphate nucleotides, and ecto-5'-nucleotidase, which hydrolyzes AMP, have been characterized in T. vaginalis. The aim of this study was to characterize the adenosine deaminase (ADA) activity in intact trophozoites of T. vaginalis. A strong inhibition in adenosine deamination was observed in the presence of calcium and magnesium, which was prevented by EDTA. The apparent K(M) value for adenosine was 1.13 ± 0.07mM. The calculated V(max) was 2.61 ± 0.054 nmol NH(3) min(-1) mg(-1) protein. Adenosine deamination was inhibited in the presence of erythro-9-(2-hydroxy-3-nonyl)adenine. Semi-quantitative reverse transcriptase-PCR experiments were performed and both ADA-related genes ada(125) and ada(231) mRNA were expressed, although ada(231) in higher quantity when compared with the ada(125) : α-tubulin ratio. Furthermore, a phylogenetic analysis showed that the T. vaginalis sequences formed a clade with Entamoeba histolytica and Dictyostelium discoideum sequences, and it strongly suggests homologous functions in the T. vaginalis genome. The presence of ADA activity in T. vaginalis may be important to modulate the adenosine/inosine levels during infection and, consequently, to maintain the anti-inflammatory properties through different nucleoside-signalling mechanisms.

Candimine-induced cell death of the amitochondriate parasite Trichomonas vaginalis

Candimine (1), an alkaloid from the bulbs of Hippeastrum morelianum, was found to be cytotoxic for the amitochondriate parasite Trichomonas vaginalis. Candimine (1) induced cell death with an unprecedented group of effects that failed to fulfill the criteria for apoptosis and apoptosis-like death already reported in trichomonads. Arrest of the parasite cell cycle, and morphologic and ultrastructural alterations, including marked cytoplasmic vacuolization, were induced by 1. The present findings suggest some similarities to paraptotic cell death, described for multicellular organisms. This study contributes to both a better understanding of the biological effects of 1 and T. vaginalis cell biology.

[Trichomoniasis: prevalence in the female gender in 2004-2005 in Sergipe State, Brazil]

Trichomoniasis is a disease caused by the protozoan Trichomonas vaginalis, which initiates a wide variety of clinical manifestations. It may be associated with human immunodeficiency virus, cervical cancer, infertility and other diseases. Its incidence ranges from 20% up to 40% in Brazil. The primary channel of transmission is by sexual contact and laboratorial diagnostic may be performed by chain polymerase reaction (CPR), culture medium isolation, fresh vaginal content exam and/or colored by Giemsa and Papanicolau methods. The later has limitations in the detection of pathologies considered sexually transmissible, like Thricomoniasis. This work deals with prevalence of Thricomoniasis in users of laboratories associated with the Ministry of Health, in the age group from 19 up to 44 years old which were submitted to Papanicolau test in 2004-2005 in Sergipe state, Brazil. Results have revealed that among 206,034 users, 7,349 have shown Thricomoniasis, being 3,788 in 2004 and 3,498 in 2005. It could be observed that the estimated prevalence in Sergipe in the biennium studied did not corroborate with the Brazilian reality, which may be attributed to the diagnostic executed.

Proteome analysis of the surface of Trichomonas vaginalis reveals novel proteins and strain-dependent differential expression

The identification of surface proteins on the plasma membrane of pathogens is of fundamental importance in understanding host-pathogen interactions. Surface proteins of the extracellular parasite Trichomonas are implicated in the initial adherence to mucosal tissue and are likely to play a critical role in the long term survival of this pathogen in the urogenital tract. In this study, we used cell surface biotinylation and multidimensional protein identification technology to identify the surface proteome of six strains of Trichomonas vaginalis with differing adherence capacities to vaginal epithelial cells. A combined total of 411 proteins were identified, and of these, 11 were found to be more abundant in adherent strains relative to less adherent parasites. The mRNA levels of five differentially expressed proteins selected for quantitative RT-PCR analysis mirrored their observed protein levels, confirming their up-regulation in highly adherent strains. As proof of principle and to investigate a possible role in pathogenesis for differentially expressed proteins, gain of function experiments were performed using two novel proteins that were among the most highly expressed surface proteins in adherent strains. Overexpression of either of these proteins, TVAG_244130 or TVAG_166850, in a relatively non-adherent strain increased attachment of transfected parasites to vaginal epithelial cells approximately 2.2-fold. These data support a role in adhesion for these abundant surface proteins. Our analyses demonstrate that comprehensive profiling of the cell surface proteome of different parasite strains is an effective approach to identify potential new adhesion factors as well as other surface molecules that may participate in establishing and maintaining infection by this extracellular pathogen.

Regulation of gene expression in protozoa parasites

Infections with protozoa parasites are associated with high burdens of morbidity and mortality across the developing world. Despite extensive efforts to control the transmission of these parasites, the spread of populations resistant to drugs and the lack of effective vaccines against them contribute to their persistence as major public health problems. Parasites should perform a strict control on the expression of genes involved in their pathogenicity, differentiation, immune evasion, or drug resistance, and the comprehension of the mechanisms implicated in that control could help to develop novel therapeutic strategies. However, until now these mechanisms are poorly understood in protozoa. Recent investigations into gene expression in protozoa parasites suggest that they possess many of the canonical machineries employed by higher eukaryotes for the control of gene expression at transcriptional, posttranscriptional, and epigenetic levels, but they also contain exclusive mechanisms. Here, we review the current understanding about the regulation of gene expression in Plasmodium sp., Trypanosomatids, Entamoeba histolytica and Trichomonas vaginalis.

Trichomonas vaginalis nucleoside triphosphate diphosphohydrolase and ecto-5'-nucleotidase activities are inhibited by lycorine and candimine

Drug discovery from plants plays an important role in the pharmaceutical therapy field and the alkaloids lycorine and candimine are candidates for this purpose. Trichomonas vaginalis is a parasite that infects the human urogenital tract and causes trichomonosis, the most prevalent non-viral sexually transmitted disease. Ecto-nucleotidases including nucleoside triphosphate diphosphohydrolase (NTPDase) members, which hydrolyses extracellular ATP (adenosine triphosphate) and ADP (adenosine diphosphate), and ecto-5'-nucleotidase, which hydrolyses AMP (adenosine monophosphate), have been characterized in T. vaginalis. Because purine nucleotides are released from cells under physiological and stress conditions, the goal of this study was to evaluate the effect of lycorine and candimine on T. vaginalis NTPDase and ecto-5'-nculeotidase activities. The alkaloids (50 to 250microM) were tested against both long-term-grown and clinical isolates. Specific enzymatic activities were expressed as nmolPi released/min/mg protein. The effect of both alkaloids at NTPDase A and B expression levels was investigated. When the alkaloids were added directly to the reaction mixture, no effect on ATP, ADP or AMP hydrolysis was observed. NTPDase and ecto-5'-nucleotidase activities were strongly inhibited by candimine and lycorine on 24h-treated parasites. This effect was abolished when 24-treated parasites were innoculated in a culture medium without alkaloid. Transcript levels of NTPDase A or B were not altered by the alkaloids. Considering the cytotoxic and proinflammatory roles of ATP besides the anti-inflammatory effects of adenosine, the regulation of extracellular nucleotide levels could be relevant in increasing susceptibility of T. vaginalis to host immune response in the presence of lycorine and candimine.

Trichomonas vaginalis: dehydroepiandrosterone sulfate and 17beta-estradiol alter NTPDase activity and gene expression

We investigated the effect of dehydroepiandrosterone sulfate (DHEAS) and 17beta-estradiol on NTPDase activity in fresh clinical (VP60) and long-term-grown (30236 ATCC) isolates of Trichomonas vaginalis followed by NTPDase gene transcriptional analysis. ATP hydrolysis was activated in vitro by 17beta-estradiol (0.01-1.0microM) in the VP60 isolate. Treatment for 2h with 17beta-estradiol (0.01-1microM) promoted an inhibition in nucleotide hydrolysis in the 30236 isolate whereas the 12h-treatment promoted an activation of nucleotide hydrolysis in both isolates. ADP hydrolysis was inhibited in vitro by 1.0-5.0microM DHEAS in the ATCC isolate. The treatment with DHEAS (0.01-1.0microM) for 2h inhibited ATP and ADP hydrolysis in VP60; however, during a 12h-treatment with DHEAS, nucleotide hydrolysis was inhibited in both isolates. Two NTPDase orthologous (NTPDaseA and NTPDaseB) were identified and the treatment with DHEAS for 12h was able to inhibit mRNA NTPDaseA transcript levels from the VP60. These findings demonstrate that NTPDase activity and gene expression pattern are modulated by exposure to steroids in T. vaginalis.

Trichomonas vaginalis vast BspA-like gene family: evidence for functional diversity from structural organisation and transcriptomics

Background

Trichomonas vaginalis is the most common non-viral human sexually transmitted pathogen and importantly, contributes to facilitating the spread of HIV. Yet very little is known about its surface and secreted proteins mediating interactions with, and permitting the invasion and colonisation of, the host mucosa. Initial annotations of T. vaginalis genome identified a plethora of candidate extracellular proteins.

Results

Data mining of the T. vaginalis genome identified 911 BspA-like entries (TvBspA) sharing TpLRR-like leucine-rich repeats, which represent the largest gene family encoding potential extracellular proteins for the pathogen. A broad range of microorganisms encoding BspA-like proteins was identified and these are mainly known to live on mucosal surfaces, among these T. vaginalis is endowed with the largest gene family. Over 190 TvBspA proteins with inferred transmembrane domains were characterised by a considerable structural diversity between their TpLRR and other types of repetitive sequences and two subfamilies possessed distinct classic sorting signal motifs for endocytosis. One TvBspA subfamily also shared a glycine-rich protein domain with proteins from Clostridium difficile pathogenic strains and C. difficile phages. Consistent with the hypothesis that TvBspA protein structural diversity implies diverse roles, we demonstrated for several TvBspA genes differential expression at the transcript level in different growth conditions. Identified variants of repetitive segments between several TvBspA paralogues and orthologues from two clinical isolates were also consistent with TpLRR and other repetitive sequences to be functionally important. For one TvBspA protein cell surface expression and antibody responses by both female and male T. vaginalis infected patients were also demonstrated.

Conclusions

The biased mucosal habitat for microbial species encoding BspA-like proteins, the characterisation of a vast structural diversity for the TvBspA proteins, differential expression of a subset of TvBspA genes and the cellular localisation and immunological data for one TvBspA; all point to the importance of the TvBspA proteins to various aspects of T. vaginalis pathobiology at the host-pathogen interface.

Isolation of a novel ras gene from Trichomonas vaginalis: a possible evolutionary ancestor of the Ras and Rap genes of higher eukaryotes

The Ras subfamily proteins are small, monomeric GTP-binding proteins with vital roles in regulating eukaryotic signal transduction pathways. Gene duplication and divergence have been postulated as the mechanism by which such family members have evolved their specific functions. A cDNA clone of TvRsp was isolated and sequenced from a cDNA expression library of the primitive eukaryote Trichomonas vaginalis. The genomic DNA corresponding to the cDNA sequence was amplified by PCR and sequenced. Sequence analysis suggested that TvRsp was an intronless gene. This gene encoded a protein of 181 amino acids and contained the 5 conserved G domains that designated it as a Ras or Rap subfamily member. However, the deduced amino acid sequence shared only 34%-37% overall identity with other Ras subfamily members of different species, and the presence of motifs characteristic of both the Ras and Rap families of GTPase confused the familial classification of this gene. Phylogenetic analysis showed its origins at the divergence point of the Ras/Rap families and suggested that TvRsp was a possible evolutionary ancestral gene of the ras/rap genes of higher eukaryotes. This information was of importance not only from the perspective of understanding the evolution and diversity of eukaryotic signal transduction pathways but also in providing a framework by which to understand protein processing in the growth and differentiation of single-celled microorganisms.

Iron modulates ecto-phosphohydrolase activities in pathogenic trichomonads

The presence of iron in the extracellular medium is essential for both in vivo and in vitro survival of pathogenic microorganisms, including Trichomonas vaginalis and Tritrichomonas foetus. In these parasites, iron is directly involved in the proliferation, protein expression and activation of critical enzymes. The purpose of this study was to investigate the role of iron in ecto-ATPase, ecto-phophatase and secreted phosphatase activities of these trichomonads. We observed that trichomonads grown in iron-depleted medium exhibited a remarkable decrease in both ecto-ATPase and ecto-phosphatase activities, when compared to those cultivated under control conditions (iron-rich medium). Furthermore, parasites grown in iron-depleted medium restored their enzyme activities when they were re-inoculated into fresh iron-rich medium. We demonstrated that modulation of ecto-phosphohydrolase activities is due neither to enzyme-iron nor to substrate-iron complex formation, since iron addition directly to the medium where the enzymatic reactions occurred did not alter their activities. Previously, we had reported that a fresh clinical isolate of T. vaginalis was much more cytotoxic to epithelial cell monolayers than a long-term cultured one. In this study we witnessed that the fresh isolate of T. vaginalis presented higher activities to all herein investigated enzymes than the long-term cultured one. Altogether, our data clearly point out that iron has a pivotal role in the expression of phosphohydrolases in both trichomonads.

Identification of a very large Rab GTPase family in the parasitic protozoan Trichomonas vaginalis

Rab proteins are pivotal components of the membrane trafficking machinery in all eukaryotes. Distinct Rab proteins locate to specific endomembrane compartments and genomic studies suggest that Rab gene diversity correlates with endomembrane system complexity; for example unicellular organisms generally possess 5-20 Rab family members and the size of the repertoire increases to 25-60 in multicellular systems. Here we report 65 open reading frames from the unicellular protozoan Trichomonas vaginalis that encode distinct Rab proteins (TvRabs), indicating a family with complexity that rivals Homo sapiens in number. The detection of gene transcripts for the majority of these genes and conservation of functional motifs strongly suggests that TvRabs retain functionality and likely roles in membrane trafficking. The T. vaginalis Rab family includes orthologues of the conserved subfamilies, Rab1, Rab5, Rab6, Rab7 and Rab11, but the majority of TvRabs are not represented by orthologues in other systems and includes six novel T. vaginalis specific Rab subfamilies (A-F). The extreme size of the T. vaginalis Rab family, the presence of novel subfamilies plus the divergent nature of many TvRab sequences suggest both the presence of a highly complex endomembrane system within Trichomonas and potentially novel Rab functionality. A family of more than 65 Rab genes in a unicellular genome is unexpected, but may be a requirement for progression though an amoeboid life-cycle phase as both Dictyostelium discoideum and Entamoeba histolytica share with T. vaginalis both an amoeboid life cycle stage and very large Rab gene families.

Molecular and phylogenetic characterization of syntaxin genes from parasitic protozoa

Vesicular transport is an integral process in eukaryotic cells and the syntaxins, a member of the SNARE protein superfamily, are a critical piece of the vesicular transport machinery. We have obtained syntaxin homologues from diverse protozoan parasites (including Entamoeba, Giardia, Trichomonas and Trypanosoma), determined the paralogue affinity of the homologues by molecular phylogenetics and compared functionally critical amino acid sites identified in other syntaxins. Surprisingly, three sequences deviate at the signature glutamine residue position, conserved in all previously identified syntaxin homologues. It is known that, despite conserved structure and function of both the syntaxins and the proteins of the regulatory SM superfamily, the various syntaxin paralogues bind their respective SM partners at different regions of the syntaxin molecule. These sites of interactions have been identified down to the individual residues. The pattern of conservation at these residues, in our evolutionarily diverse sampling of syntaxin paralogues, is therefore used to gain further insight into the interaction of these proteins. Phylogenetic analysis confirms and extends previous conclusions that the syntaxin families are present in diverse eukaryotes and that the syntaxin sub-families diverged early in eukaryotic evolution. This result is expanded with the inclusion of new homologues for previously sampled taxa, newly sampled taxa, and newly sampled syntaxin sub-families. Because of their integral role in membrane trafficking, the syntaxin genes represent a valuable potential molecular marker for the experimental study of the endomembrane system of disease-causing protists.

Trichomonas vaginalis: cytochemical localization of a NTPDase1 and an ecto-5'-nucleotidase and effects of adenine nucleotides on cellular viability

Nucleoside triphosphate diphosphohydrolase 1 (NTPDase1), which hydrolyzes extracellular ATP and ADP, and ecto-5'-nucleotidase, which hydrolyzes AMP, are characterized for Trichomonas vaginalis. Ultrastructural cytochemical microscopy showed NTPDase1 and ecto-5'-nucleotidase activities on the surface of the parasites. High levels of extracellular adenine nucleotides and adenosine did not exert cytolytic effects in intact cells of T. vaginalis. Our results suggest that these enzymes are relevant for the survival of the parasite during exposure to extracellular nucleotides. Since the ecto-localization of these enzymes is essential for the maintenance of adenosine extracellular levels, this nucleoside could be important for the purine salvage pathway in the parasite.

Effects of metronidazole and tinidazole on NTPDase1 and ecto-5'-nucleotidase from intact cells of Trichomonas vaginalis

Here we report the effects of metronidazole and tinidazole on NTPDase1 and ecto-5'-nucleotidase from intact cells of Trichomonas vaginalis. Adenosine triphosphate (ATP) and adenosine diphosphate (ADP) hydrolysis was 5- to 7-fold higher for the fresh clinical strain, when compared with the ATCC (American Type Culture Collection) strain. ATP hydrolysis was activated in the presence of metronidazole in the ATCC strain, whilst it was inhibited 33% by 50 microM tinidazole in a fresh clinical isolate. The treatment of cells in the presence of metronidazole for 2 h inhibited ATP and ADP hydrolysis, whilst treatment with tinidazole inhibited ATP and ADP hydrolysis only in the fresh clinical isolate. The drugs did not change the ecto-5'-nucleotidase activity for both strains. Our results suggest that the modulation of extracellular ATP and ADP levels during treatment with these drugs could be a parasitic defence strategy as a survival mechanism in an adverse environment.

Perspective of a new diagnostic for human trichomonosis

Several diagnostic techniques have been employed for the detection of Trichomonas vaginalis. Microtubules constitute the cytoskeleton in eukaryotic cells and are sensitive to antimitotic drugs, such as Taxol (paclitaxel). We used FLUTAX a fluorescent taxoid - to analyze the microtubule distribution in living trophozoites of T. vaginalis in urine and in vaginal discharge. A high intensity of fluorescence was observed in living T. vaginalis, epithelial cells and leukocytes present in urine and vaginal discharge. Our preliminary results show the perspective of a new diagnostic technique for trichomonosis and will contribute to the understanding of the cytoskeleton of T. vaginalis.

A clinical study on the association of Trichomonas vaginalis and Mycoplasma hominis infections in women attending a sexually transmitted disease (STD) outpatient clinic

Swabs from the posterior vaginal fornix were obtained from 804 consecutive female patients visiting a large Dutch sexually transmitted diseases (STD) outpatient clinic. A detailed clinical history was obtained and complaints concerning the lower genital tract, such as vaginal discharge or vulval and vaginal irritation, were recorded. Patients were examined and the presence of non-physiological vaginal secretions was established by speculum examination. The swabs were monitored for bacterial vaginosis (BV) or Candida albicans infection. PCR diagnosis of Chlamydia trachomatis and Trichomonas vaginalis was performed as well. Four groups of patients (n=14-21) with BV or single infections caused by one of these three pathogens and a control group with no pathogens were selected and Mycoplasma hominis PCR was performed additionally. At clinical presentation, controls and single-infected patient groups were comparable with regard to complaints of the lower genital tract and sexual risk behavior defined as having prior STDs and/or admitted prostitution. Only in the T. vaginalis-positive group significantly more women reporting sexual risk behavior were found than in controls. In agreement with former in vitro observations, an in vivo association between the PCR-detected presence of M. hominis and T. vaginalis was established. In 79% of all samples positive for T. vaginalis, M. hominis could be detected, as compared to only 6% in control samples (P=0.0004). However, since single infections by either of the two pathogens were regularly observed, there does not seem to be an exclusive association between the species, as the bacterium is also more frequently found in cases of BV (P=0.026). Co-infection of M. hominis with C. albicans (11%) or C. trachomatis (0%) did not differ significantly from controls (6%). M. hominis did not associate with complaints of the lower genital tract. However, if all groups were combined there appears to be a very significant association between the presence of M. hominis and sexual risk behavior (P=0.0004). M. hominis and sexual risk behavior were more closely associated than M. hominis and T. vaginalis. No indications were found for an enhanced pathogenicity by either of the symbionts.