Trichomonas adhere and phagocytose sperm cells: adhesion seems to be a prominent stage during interaction

Endocytosis in anaerobic parasitic protists

The incorporation of different molecules by eukaryotic cells occurs through endocytosis, which is critical to the cell's survival and ability to reproduce. Although this process has been studied in greater detail in mammalian and yeast cells, several groups working with pathogenic protists have made relevant contributions. This review analysed the most relevant data on the endocytic process in anaerobic protists (Entamoeba histolytica, Giardia intestinalis, Trichomonas vaginalis, and Tritrichomonas foetus). Many protozoa can exert endocytic activity across their entire surface and do so with great intensity, as with E. histolytica. The available data on the endocytic pathway and the participation of PI-3 kinase, Rab, and Rho molecular complexes is reviewed from a historical perspective.

Phylogenetic Analysis of Pyruvate-Ferredoxin Oxidoreductase, a Redox Enzyme Involved in the Pharmacological Activation of Nitro-Based Prodrugs in Bacteria and Protozoa

The present frontrunners in the chemotherapy of infections caused by protozoa are nitro-based prodrugs that are selectively activated by PFOR-mediated redox reactions. This study seeks to analyze the distribution of PFOR in selected protozoa and bacteria by applying comparative genomics to test the hypothesis that PFOR in eukaryotes was acquired through horizontal gene transfer (HGT) from bacteria. Furthermore, to identify other putatively acquired genes, proteome-wide and gene enrichment analyses were used. A plausible explanation for the patchy occurrence of PFOR in protozoa is based on the hypothesis that bacteria are potential sources of genes that enhance the adaptation of protozoa in hostile environments. Comparative genomics of Entamoeba histolytica and the putative gene donor, Desulfovibrio vulgaris, identified eleven candidate genes for HGT involved in intermediary metabolism. If these results can be reproduced in other PFOR-possessing protozoa, it would provide more validated evidence to support the horizontal transfer of pfor from bacteria.

Trichomonas vaginalis adhesion protein 65 (TvAP65) modulates parasite pathogenicity by interacting with host cell proteins

Trichomonas vaginalis (T. vaginalis) is a widespread and important sexually transmitted pathogen. Adherence to the surface of the host cell is the precondition forthis parasite's parasitism and pathogenicity. Adhesion protein 65 (TvAP65) plays a key role in the process of adhesion. However, how TvAP65 mediates the adhesion and pathogenicity of T. vaginalis to host cellsis unclear. In this study, we knocked down the expression of TvAP65 in trophozoites by small RNA interference. The number of T. vaginalis trophozoites adhering to VK2/E6E7 cells was decreased significantly, and the inhibition of VK2/E6E7 cells proliferation and VK2/E6E7 cells apoptosis and death induced by T. vaginalis were reduced, after the expression of TvAP65 was knocked down. Animal challenge experiments showed that the pathogenicity of trophozoites was decreased by passive immunization with anti-rTvAP65 PcAbs or blocking the TvAP65 protein. Immunofluorescence analysis showed that TvAP65 could bind to VK2/E6E7 cells. In order to screen the molecules interacting with TvAP65 on the host cells, we successfully constructed the cDNA library of VK2/E6E7 cells, and thirteen protein molecules interacting with TvAP65 were screened by yeast two-hybrid system. The interaction between TvAP65 and BNIP3 was further confirmed by coimmunoprecipitation and colocalization. When both TvAP65 and BNIP3 were knocked down by small RNA interference, the number of T. vaginalis adhering to VK2/E6E7 cells and the inhibition of VK2/E6E7 cells proliferation were significantly lower than those of the group with knockdown of TvAP65 or BNIP3 alone. Therefore, the interaction of TvAP65 and BNIP3 in the pathogenesis of T. vaginalis infecting host cells is not unique and involves other molecules. Our study elucidated that the interaction between TvAP65 and BNIP3 mediated the adhesion and pathogenicity of T. vaginalis to host cells, provided a basis for searching for the drug targets of anti-T. vaginalis, and afforded new ideas for the prevention and treatment of trichomoniasis.

The interaction between adhesion protein 33 (TvAP33) and BNIP3 mediates the adhesion and pathogenicity of Trichomonas vaginalis to host cells

BACKGROUND

Trichomonas vaginalis is a widespread and important sexually transmitted pathogen. Adherence to the surface of the host cell is the precondition for the parasitism and pathogenicity of this parasite. Trichomonas vaginalis adhesion protein 33 (TvAP33) plays a key role in the process of adhesion, but how this protein mediates the adhesion and pathogenicity of T. vaginalis to host cells is unclear.

METHODS

The expression of TvAP33 in trophozoites was knocked down by small interfering RNA. VK2/E6E7 cells and mice infected with T. vaginalis were used to evaluate the pathogenicity of T. vaginalis. We constructed a complementary DNA library of VK2/E6E7 cells and screened the protein molecules interacting with TvAP33 by the yeast two-hybrid system. The interaction between TvAP33 and BNIP3 (Bcl-2 interacting protein 3) was analyzed by co-immunoprecipitation and colocalization.

RESULTS

Following knockdown of TvAP33 expression, the number of T. vaginalis trophozoites adhering to VK2/E6E7 cells decreased significantly, and the inhibition of VK2/E6E7 cell proliferation and VK2/E6E7 cell apoptosis and death induced by T. vaginalis were reduced. Animal challenge experiments showed that the pathogenicity of trophozoites decreased following passive immunization with TvAP33 antiserum or blocking of the TvAP33 protein. Immunofluorescence analysis revealed that TvAP33 could bind to VK2/E6E7 cells. Eighteen protein molecules interacting with TvAP33 were identified by the yeast two-hybrid system. The interaction between TvAP33 and BNIP3 was further confirmed by co-immunoprecipitation and colocalization. When the expression of both TvAP33 and BNIP3 in trophozoites was knocked down by small RNA interference, the number of T. vaginalis adhering to VK2/E6E7 cells and the inhibition of VK2/E6E7 cell proliferation were significantly lower compared to trophozoites with only knockdown of TvAP33 or only BNIP3. Therefore, the interaction of TvAP33 and BNIP3 in the pathogenesis of T. vaginalis infecting host cells is not unique and involves other molecules.

CONCLUSIONS

Our study showed that the interaction between TvAP33 and BNIP3 mediated the adhesion and pathogenicity of T. vaginalis to host cells, providing a basis for searching for drug targets for T. vaginalis as well as new ideas for the prevention and treatment of trichomoniasis.

Trichomoniasis

Trichomoniasis is the most common nonviral sexually transmitted infection worldwide. It has been associated with a variety of adverse sexual and reproductive health outcomes for both men and women. In this review, the authors discuss updates in its epidemiology, pathophysiology, clinical significance, diagnosis, and treatment.

Trichomonas vaginalis excretory secretory proteins reduce semen quality and male fertility

Trichomonas vaginalis (T. vaginalis) infection is the most common non-viral sexually transmitted disease (STD) in the world. It can cause male reproductive dysfunction and infertility. However, the pathogenic mechanism is not clear. In this study, the excretory secretory proteins of T. vaginalis (TvESPs) were collected, concentrated, and sterilized. After sperm co-cultured with TvESPs, the survival rate and motility of sperms were analyzed by seminal routine examination, and the results showed that the TvESPs could significantly reduce the survival rate and motility of sperms. Fluorescence staining displayed that TvESPs could destroy the integrity of sperm acrosomes. Flow cytometry indicated that TvESPs induced sperm apoptosis. By mouse in vitro fertilization, we confirmed that TvESPs could significantly reduce the fertilization ability of sperms and negatively affect the development of the fertilized ovum. Via semi-quantitative analysis, we found that the apoptosis-related p27, SMAC, p53, BAX, BCL-2, XIAP, and BCL-W molecules were down-regulated in mouse sperm cells after interaction between the sperms and TvESPs, which played an important role in regulating sperm apoptosis. In conclusion, our study showed that T. vaginalis degraded semen quality and negatively affected male fertility by TvESPs. TvESPs may damage sperms by breaking the balance between sperm pro-apoptotic and anti-apoptotic molecules. This study proves that T. vaginalis infection is a risk factor for infertility.

What about the bull? A systematic review about the role of males in bovine infectious infertility within cattle herds

Numerous pathogens affect cow fertility. Nevertheless, little information has been published about microorganisms associated with cattle infertility focusing on bulls. The present review offers a current analysis and highlights potential key aspects on the relevance of bulls in the emergence of infertility problems of infectious origin within herds that are still not completely determined. The present systematic review was conducted using the PubMed, Web of Science, and Scopus databases on December 9, 2022. In total, 2,224 bibliographic records were reviewed and, according to strict inclusion criteria, 38 articles were selected from 1966 to 2022, from which we ranked more than 27 different microorganisms (fungi were not identified). The most cited pathogens were BoHV (described by 26.3% of the papers), Campylobacter fetus (23.7%), Tritrichomonas foetus (18.4%), and BVDV, Ureaplasma spp., and Mycoplasma spp. (10.5% each). Despite the general trend towards an increasing number of publications about bull-infertility problems, a number of pathogens potentially transmitted through both natural breeding and seminal doses given to females and associated with infertility within herds were not ranked in the study (e.g., Chlamydia spp.). This work highlights i) the need to clearly establish the role of certain microorganisms not traditionally associated with reproductive problems in bull infertility (e.g., Staphylococcus spp. or BoHV-4) and ii) the need to perform additional studies on breeding bulls to clarify their role in infertility problems within herds. This would allow monitoring for pathogens that have gone unnoticed and those that are fastidious to diagnose and/or potentially transmitted to females.

A systematic review of the correlation between Trichomonas vaginalis infection and infertility

BACKGROUND

Trichomonas vaginalis (T. vaginalis) is an extracellular flagellated protozoan parasitizing the human genital and urinary tracts. T. vaginalis infection impacts human reproductive function, but whether it causes infertility is still a matter of debate.

METHODS

In this work, we consulted 205 relevant articles, which were classified into three categories: epidemiological investigations (100), review articles (43), and research articles (62). RevMan 5.4 was used to conduct a meta-analysis of the articles reporting epidemiological investigations comparing the incidence of T. vaginalis infection between infertile and fertile groups. Review and research articles were used to summarize the pathogenesis of infertility caused by T. vaginalis.

RESULTS

The results indicated that rate of T. vaginalis infection in the infertile group was significantly higher than that in the fertile group. Moreover, the epidemiological surveys showed that the infertility rates of population infected with T. vaginalis were significantly higher than that of population without T. vaginalis infection. Nine out of ten (90%) related review articles stated that T. vaginalis infection causes infertility, and the review and research articles indicated the main pathogenic mechanisms of infertility caused by T. vaginalis were as follows: T. vaginalis impairs sperm quality, resulting in infertility; the immune response triggered by T. vaginalis infection impacts human reproductive function.

CONCLUSION

Our results confirm that there is a correlation between T. vaginalis infection and infertility, and T. vaginalis infection can lead to infertility. The study provides a foundation for further investigations into its pathogenesis.

Proteomic Analysis of Trichomonas vaginalis Phagolysosome, Lysosomal Targeting, and Unconventional Secretion of Cysteine Peptidases

The lysosome represents a central degradative compartment of eukaryote cells, yet little is known about the biogenesis and function of this organelle in parasitic protists. Whereas the mannose 6-phosphate (M6P)-dependent system is dominant for lysosomal targeting in metazoans, oligosaccharide-independent sorting has been reported in other eukaryotes. In this study, we investigated the phagolysosomal proteome of the human parasite Trichomonas vaginalis, its protein targeting and the involvement of lysosomes in hydrolase secretion. The organelles were purified using Percoll and OptiPrep gradient centrifugation and a novel purification protocol based on the phagocytosis of lactoferrin-covered magnetic nanoparticles. The analysis resulted in a lysosomal proteome of 462 proteins, which were sorted into 21 classes. Hydrolases represented the largest functional class and included proteases, lipases, phosphatases, and glycosidases. Identification of a large set of proteins involved in vesicular trafficking (80) and turnover of actin cytoskeleton rearrangement (29) indicate a dynamic phagolysosomal compartment. Several cysteine proteases such as TvCP2 were previously shown to be secreted. Our experiments showed that secretion of TvCP2 was strongly inhibited by chloroquine, which increases intralysosomal pH, thus indicating that TvCP2 secretion occurs through lysosomes rather than the classical secretory pathway. Unexpectedly, we identified divergent homologues of the M6P receptor TvMPR in the phagolysosomal proteome, although T. vaginalis lacks enzymes for M6P formation. To test whether oligosaccharides are involved in lysosomal targeting, we selected the lysosome-resident cysteine protease CLCP, which possesses two glycosylation sites. Mutation of any of the sites redirected CLCP to the secretory pathway. Similarly, the introduction of glycosylation sites to secreted β-amylase redirected this protein to lysosomes. Thus, unlike other parasitic protists, T. vaginalis seems to utilize glycosylation as a recognition marker for lysosomal hydrolases. Our findings provide the first insight into the complexity of T. vaginalis phagolysosomes, their biogenesis, and role in the unconventional secretion of cysteine peptidases.

Epidemiology, natural history, diagnosis, and treatment of Trichomonas vaginalis in men

Trichomonas vaginalis infections in men are traditionally considered to be benign and consequently have been overlooked. However, men with this common sexually transmitted infection can experience urethritis, prostatitis, reduced fertility, and amplified HIV risk. In addition, men are often asymptomatic and can unknowingly spread the infection to their female sexual partners. With advances in T. vaginalis diagnostics, more men are being diagnosed, yet the optimal method of treatment in men remains unknown. The purpose of this review is to discuss the epidemiology, natural history, diagnosis, and treatment of T. vaginalis among men.

Trichomonas vaginalis infection impairs anion secretion in vaginal epithelium

Trichomonas vaginalis is a common protozoan parasite, which causes trichomoniasis associated with severe adverse reproductive outcomes. However, the underlying pathogenesis has not been fully understood. As the first line of defense against invading pathogens, the vaginal epithelial cells are highly responsive to environmental stimuli and contribute to the formation of the optimal luminal fluid microenvironment. The cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel widely distributed at the apical membrane of epithelial cells, plays a crucial role in mediating the secretion of Cl⁻ and HCO₃⁻. In this study, we investigated the effect of T. vaginalis on vaginal epithelial ion transport elicited by prostaglandin E₂ (PGE₂), a major prostaglandin in the semen. Luminal administration of PGE₂ triggered a remarkable and sustained increase of short-circuit current (I_SC) in rat vaginal epithelium, which was mainly due to Cl⁻ and HCO₃⁻ secretion mediated by the cAMP-activated CFTR. However, T. vaginalis infection significantly abrogated the I_SC response evoked by PGE₂, indicating impaired transepithelial anion transport via CFTR. Using a primary cell culture system of rat vaginal epithelium and a human vaginal epithelial cell line, we demonstrated that the expression of CFTR was significantly down-regulated after T. vaginalis infection. In addition, defective Cl⁻ transport function of CFTR was observed in T. vaginalis-infected cells by measuring intracellular Cl⁻ signals. Conclusively, T. vaginalis restrained exogenous PGE₂-induced anion secretion through down-regulation of CFTR in vaginal epithelium. These results provide novel insights into the intervention of reproductive complications associated with T. vaginalis infection such as infertility and disequilibrium in vaginal fluid microenvironment.

Trichomonas vaginalis is a common sexually transmitted parasite that colonized the urogenital mucosa and causes trichomoniasis, a neglected sexually transmitted infection associated with multiple adverse reproductive outcomes in humans. However, the underlying mechanisms remain largely unknown. The epithelial cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel conducting both Cl⁻ and HCO₃⁻, which participates in the regulation of luminal fluid microenvironment conducive to the success of reproductive events. Prostaglandin E₂ (PGE₂), a bioactive molecule abundant in human seminal fluid, has been demonstrated to exhibit a robust pro-secretory action by activating CFTR in the female genital tract epithelial cells such as endometrial epithelium. These discoveries motivated the authors to investigate the effect of T. vaginalis infection on exogenous PGE₂-induced transepithelial transport of electrolytes in vagina. Here, we found that in rat vaginal epithelium, luminal administration of PGE₂ elicited a response of Cl⁻ and HCO₃⁻ secretion mediated by cAMP-activated CFTR. However, T. vaginalis infection impaired transepithelial anion transport evoked by PGE₂, which is probably related to the defective expression and function of CFTR. These outcomes may complement and expand our knowledge of the complex interaction between T. vaginalis and the infected host, providing a novel therapeutic strategy for disequilibrium in vaginal fluid microenvironment and infertility induced by T. vaginalis infection.

Interaction of Mycobacterium avium subsp. paratuberculosis with bovine sperm

Mycobacterium avium subsp. paratuberculosis (MAP) is responsible for Paratuberculosis mainly affecting domestic ruminants. The interaction between MAP and sperm and/or germ cells has not yet been established, however the adherence between MAP and the host cell surface is associated to the 85 complex proteins that bind to the host cell's fibronectin. Therefore, this study aimed to evaluate the binding of MAP to bovine sperm and to verify changes in these cells by the presence of MAP before and after sperm cryopreservation. Polyclonal antibodies to MAP 85 complex proteins were produced and utilized in the analyzes. Two Nelore bulls were used for semen collection and MAP dilutions (10³-10⁸ CFU/mL) were inoculated in the samples; sperm motility and vigor were evaluated using light microscopy at different times before and after cryopreservation and in the presence and absence of the antibodies 85A and 85B. Interaction of MAP and sperm, interaction of MAP and sperm in the presence of Ab 85A and in the presence of Ab 85B were analyzed by scanning electron microscopy. The viability of MAP after sperm cryopreservation were evaluated by plating the samples after thawing. It was observed that sperm in the presence of MAP shows a decrease in motility and vigor, and that the higher the MAP concentration, the lower the sperm performance. It was possible to determine the viability of MAP after cryopreservation in samples of higher concentrations, which demonstrates the potential of transmission of this pathogen through artificial insemination. The interaction of MAP with bovine sperm occurs mainly in the midpiece and may be linked to the proteins 85A and 85B present in the MAP membrane.

Effects of Campylobacter fetus on bull sperm quality

Campylobacter fetus is a gram-negative, motile, spiral or S-shaped bacterium, which induces campylobacteriosis. This disease causes decrease productivity of cattle. Although considerable research has been done on the role of C. fetus on female fertility, little is known about the effect on bulls. The aim of this work was to evaluate the effect of C. fetus subsp. fetus (Cff) and C. fetus subsp. venerealis (Cfv) on bull sperm quality. Samples of frozen semen (n = 29 straws) were each distributed into three groups: two of them incubated with the microorganism (Cff, Cfv) and a control group. The proportions of live spermatozoa, with functional membrane and true acrosomal reaction in control group were significantly (P < 0.01) greater than those observed in Cff and Cfv groups. However, no significant differences (P > 0.05) were found in sperm chromatin structure among treatments. In adhesion assay, proportions of spermatozoa with adhered Campylobacter were similar for both subspecies. Results confirm that Cff and Cfv have the same ability to bind in an irreversible way to bull spermatozoa and to affect sperm quality. It is proposed that adherence could be considered as the main cause of sperm alterations, and also an important step of pathogenesis and venereal transmission.

Time to re-evaluate the guidance on sexual infections in fertility services

Current guidance in the UK for fertility services on the screening for sexually transmitted infections (STI) is solely directed towards Chlamydia trachomatis. Evidence used to formulate the guidance is based on research undertaken before more sensitive diagnostic methods were available and before testing of some organisms was even possible. This commentary outlines current STI trends, evidence available for STI effect on fertility and new diagnostic methods of screening. It aims to demonstrate that UK guidance should be updated and directed towards areas where further research is required.

A Novel Cadherin-like Protein Mediates Adherence to and Killing of Host Cells by the Parasite Trichomonas vaginalis

Trichomonas vaginalis, a prevalent sexually transmitted parasite, adheres to and induces cytolysis of human mucosal epithelial cells. We have characterized a hypothetical protein, TVAG_393390, with predicted tertiary structure similar to that of mammalian cadherin proteins involved in cell-cell adherence. TVAG_393390, renamed cadherin-like protein (CLP), contains a calcium-binding site at a position conserved in cadherins. CLP is surface localized, and its mRNA and protein levels are significantly upregulated upon parasite adherence to host cells. To test the roles of CLP and its calcium-binding dependency during host cell adherence, we first demonstrated that wild-type CLP (CLP) binds calcium with a high affinity, whereas the calcium-binding site mutant protein (CLP-mut) does not. CLP and CLP-mut constructs were then used to overexpress these proteins in T. vaginalis Parasites overexpressing CLP have ∼3.5-fold greater adherence to host cells than wild-type parasites, and this increased adherence is ablated by mutating the calcium-binding site. Additionally, competition with recombinant CLP decreased parasite binding to host cells. We also found that overexpression of CLP induced parasite aggregation which was further enhanced in the presence of calcium, whereas CLP-mut overexpression did not affect aggregation. Lastly, parasites overexpressing wild-type CLP induced killing of host cells ∼2.35-fold, whereas parasites overexpressing CLP-mut did not have this effect. These analyses describe the first parasitic CLP and demonstrate a role for this protein in mediating parasite-parasite and host-parasite interactions. T. vaginalis CLP may represent convergent evolution of a parasite protein that is functionally similar to the mammalian cell adhesion protein cadherin, which contributes to parasite pathogenesis.IMPORTANCE The adherence of pathogens to host cells is critical for colonization of the host and establishing infection. Here we identify a protein with no known function that is more abundant on the surface of parasites that are better at binding host cells. To interrogate a predicted function of this protein, we utilized bioinformatic protein prediction programs which allowed us to uncover the first cadherin-like protein (CLP) found in a parasite. Cadherin proteins are conserved metazoan proteins with central roles in cell-cell adhesion, development, and tissue structure maintenance. Functional characterization of this CLP from the unicellular parasite Trichomonas vaginalis demonstrated that the protein mediates both parasite-parasite and parasite-host adherence, which leads to an enhanced killing of host cells by T. vaginalis Our findings demonstrate the presence of CLPs in unicellular pathogens and identify a new host cell binding protein family in a human-infective parasite.

Review: Risks of disease transmission through semen in cattle

The purpose of this paper is to review scientific evidence concerning pathogens that could potentially be transmitted via bovine semen. As a result of a careful analysis of the characteristics of infections that may cause transmission of disease through semen, effective control procedures can be identified that provide minimal constraint to the introduction of new bulls into herds for natural breeding and importation of valuable novel genetics through artificial insemination. The potential for transmission through bovine semen and corresponding effective control procedures are described for bovine herpesvirus 1, bovine viral diarrhea virus, bovine leukemia virus, lumpy skin disease virus, bluetongue virus, foot-and-mouth disease virus, and Schmallenberg virus. Brief consideration is also provided regarding the potential for transmission via semen of Tritrichomonas foetus, Campylobacter fetus venerealis, Brucella abortus, Leptospira spp., Histophilus somni, Ureaplasma diversum, Mycobacterium avium subsp. paratuberculosis, Chlamydiaceae, Mycobacterium bovis, Coxiella burnetii, Mycoplasma mycoides ssp. mycoides and Neospora caninum. Thoughtful and systematic control procedures can ensure the safety of introducing new bulls and cryopreserved semen into cattle production systems.

Dynamic secretome of Trichomonas vaginalis: Case study of β-amylases

The secretion of virulence factors by parasitic protists into the host environment plays a fundamental role in multifactorial host-parasite interactions. Several effector proteins are known to be secreted by Trichomonas vaginalis, a human parasite of the urogenital tract. However, a comprehensive profiling of the T. vaginalis secretome remains elusive, as do the mechanisms of protein secretion. In this study, we used high-resolution label-free quantitative MS to analyze the T. vaginalis secretome, considering that secretion is a time- and temperature-dependent process, to define the cutoff for secreted proteins. In total, we identified 2 072 extracellular proteins, 89 of which displayed significant quantitative increases over time at 37 °C. These 89 bona fide secreted proteins were sorted into 13 functional categories. Approximately half of the secreted proteins were predicted to possess transmembrane helixes. These proteins mainly include putative adhesins and leishmaniolysin-like metallopeptidases. The other half of the soluble proteins include several novel potential virulence factors, such as DNaseII, pore-forming proteins, and β-amylases. Interestingly, current bioinformatic tools predicted the secretory signal in only 18% of the identified T. vaginalis-secreted proteins. Therefore, we used β-amylases as a model to investigate the T. vaginalis secretory pathway. We demonstrated that two β-amylases (BA1 and BA2) are transported via the classical endoplasmic reticulum-to-Golgi pathways, and in the case of BA1, we showed that the protein is glycosylated with multiple N-linked glycans of Hex5HexNAc2 structure. The secretion was inhibited by brefeldin A but not by FLI-06. Another two β-amylases (BA3 and BA4), which are encoded in the T. vaginalis genome but absent from the secretome, were targeted to the lysosomal compartment. Collectively, under defined in vitro conditions, our analysis provides a comprehensive set of constitutively secreted proteins that can serve as a reference for future comparative studies, and it provides the first information about the classical secretory pathway in this parasite.

Interaction between Trichomonas vaginalis and the Prostate Epithelium

Most men infected with Trichomonas vaginalis are asymptomatic and can remain undiagnosed and untreated. This has been hypothesized to result in chronic persistent prostatic infection. Adhesion of the protozoan organisms to mucosal cells is considered a first and prerequisite step for T. vaginalis infection. Adhesion of T. vaginalis to prostate epithelial cells has not yet been observed; however, there are several reports about inflammation of prostate epithelial cells induced by T. vaginalis. The aim of this study was to investigate whether adhesion and cytotoxicity of T. vaginalis are involved in inflammation of prostate epithelial cells. When RWPE-1 cells were infected with T. vaginalis (1:0.4 or 1:4), adhesion of T. vaginalis continuously increased for 24 hr or 3 hr, respectively. The cytotoxicity of prostate epithelial cells infected with T. vaginalis (RWPE-1: T. vaginalis=1:0.4) increased at 9 hr; at an infection ratio of 1:4, cytotoxicity increased after 3 hr. When the RWPE-1 to T. vaginalis ratio was 1:0.4 or 1:4, production of IL-1β, IL-6, CCL2, and CXCL8 also increased. Epithelial-mesenchymal transition (EMT) was verified by measuring decreased E-cadherin and increased vimentin expression at 24 hr and 48 hr. Taken together, the results indicate that T. vaginalis adhered to prostate epithelial cells, causing cytotoxicity, pro-inflammatory cytokine production, and EMT. Our findings suggest for the first time that T. vaginalis may induce inflammation via adhesion to normal prostate epithelial cells.

A Review of Evidence-Based Care of Symptomatic Trichomoniasis and Asymptomatic Trichomonas vaginalis Infections

Trichomonas vaginalis is the most prevalent nonviral sexually transmitted infection, affecting an estimated 3.7 million women and men in the United States. Health disparities are prominent in the epidemiology of this infection, which affects 11% of women aged ≥40 years and a disproportionately high percentage of black women. Particularly high prevalences have been identified among sexually transmitted disease (STD) clinic patients and incarcerated individuals. This article reviews and updates scientific evidence in key topic areas used for the development of the 2015 STD Treatment Guidelines published by the Centers for Disease Control and Prevention. Current evidence is presented regarding conditions associated with Trichomonas vaginalis infection, including human immunodeficiency virus (HIV) and pregnancy complications such as preterm birth. Nucleic acid amplification tests and point-of-care tests are newly available diagnostic methods that can be conducted on a variety of specimens, potentially allowing highly sensitive testing and screening of both women and men at risk for infection. Usually, trichomoniasis can be cured with single-dose therapy of an appropriate nitroimidazole antibiotic, but women who are also infected with HIV should receive therapy for 7 days. Antimicrobial resistance is an emerging concern.

Leukocyte Lysis and Cytokine Induction by the Human Sexually Transmitted Parasite Trichomonas vaginalis

Trichomonas vaginalis (Tv) is an extracellular protozoan parasite that causes the most common non-viral sexually transmitted infection: trichomoniasis. While acute symptoms in women may include vaginitis, infections are often asymptomatic, but can persist and are associated with medical complications including increased HIV susceptibility, infertility, pre-term labor, and higher incidence of cervical cancer. Heightened inflammation resulting from Tv infection could account for these complications. Effective cellular immune responses to Tv have not been characterized, and re-infection is common, suggesting a dysfunctional adaptive immune response. Using primary human leukocyte components, we have established an in vitro co-culture system to assess the interaction between Tv and the cells of the human immune system. We determined that in vitro, Tv is able to lyse T-cells and B-cells, showing a preference for B-cells. We also found that Tv lysis of lymphocytes was mediated by contact-dependent and soluble factors. Tv lysis of monocytes is far less efficient, and almost entirely contact-dependent. Interestingly, a common symbiont of Tv, Mycoplasma hominis, did not affect cytolytic activity of the parasite, but had a major impact on cytokine responses. M. hominis enabled more diverse inflammatory cytokine secretion in response to Tv and, of the cytokines tested, Tv strains cleared of M. hominis induced only IL-8 secretion from monocytes. The quality of the adaptive immune response to Tv is therefore likely influenced by Tv symbionts, commensals, and concomitant infections, and may be further complicated by direct parasite lysis of effector immune cells.

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.

The secretory products of Trichomonas vaginalis decrease fertilizing capacity of mice sperm in vitro

Trichomonas vaginalis infection is one of the most prevalent sexually transmitted infections in humans and is now recognized as an important cause of infertility in men. There is little information about the effect of extracellular polymeric substances (EPS) from T. vaginalis on sperm, but previous reports do not provide a conclusive description of the functional integrity of the sperm. To investigate the impact of EPS on the fertilizing capacity of sperm, we assessed sperm motility, acrosomal status, hypo-osmotic swelling, and in vitro fertilization rate after incubating the sperm with EPS in vitro using mice. The incubation of sperm with EPS significantly decreased sperm motility, viability, and functional integrity in a concentration and time-dependent manner. These effects on sperm quality also resulted in a decreased fertilization rate in vitro. This is the first report that demonstrates the direct negative impact of the EPS of T. vaginalis on the fertilization rate of sperm in vitro. However, further study should be performed using human sperm to determine if EPS has similar negative impact on human sperm fertilizing capacity in vitro.

Human parasitic protozoan infection to infertility: a systematic review

Protozoan parasitic diseases are endemic in many countries worldwide, especially in developing countries, where infertility is a major burden. It has been reported that such infections may cause infertility through impairment in male and female reproductive systems. We searched Medline, PubMed, and Scopus databases and Google scholar to identify the potentially relevant studies on protozoan parasitic infections and their implications in human and animal model infertility. Literature described that some of the protozoan parasites such as Trichomonas vaginalis may cause deformities of the genital tract, cervical neoplasia, and tubal and atypical pelvic inflammations in women and also non-gonoccocal urethritis, asthenozoospermia, and teratozoospermia in men. Toxopalasma gondii could cause endometritis, impaired folliculogenesis, ovarian and uterine atrophy, adrenal hypertrophy, vasculitis, and cessation of estrus cycling in female and also decrease in semen quality, concentration, and motility in male. Trypanosoma cruzi inhibits cell division in embryos and impairs normal implantation and development of placenta. Decrease in gestation rate, infection of hormone-producing glands, parasite invasion of the placenta, and overproduction of inflammatory cytokines in the oviducts and uterine horns are other possible mechanisms induced by Trypanosoma cruzi to infertility. Plasmodium spp. and Trypanosoma brucei spp. cause damage in pituitary gland, hormonal disorders, and decreased semen quality. Entamoeba histolytica infection leads to pelvic pain, salpingitis, tubo-ovarian abscess, and genital ulcers. Cutaneous and visceral leishmaniasis can induce genital lesion, testicular amyloidosis, inflammation of epididymis, prostatitis, and sperm abnormality in human and animals. In addition, some epidemiological studies have reported that rates of protozoan infections in infertile patients are higher than healthy controls. The current review indicates that protozoan parasitic infections may be an important cause of infertility. Given the widespread prevalence of parasitic protozoa diseases worldwide, we suggest further studies to better understanding of relationship between such infections and infertility.

Trichomonas vaginalis: pathogenicity and potential role in human reproductive failure

PURPOSE

Trichomonas vaginalis, which colonizes the genitourinary tract of men and women, is a sexually transmitted parasite causing symptomatic or asymptomatic trichomoniasis. The host-parasite relationship is very complex, and clinical symptoms cannot likely be attributed to a single pathogenic effect. Among the many factors responsible for interactions between T. vaginalis and host tissues, contact-dependent and contact-independent mechanisms are important in pathogenicity, as is the immune response.

METHODS

This review focuses on the potential virulence properties of T. vaginalis and its role in female and male infertility.

RESULTS

It highlights the association between T. vaginalis infection and serious adverse health consequences experienced by women, including infertility, preterm birth and low-birth-weight infants. Long-term clinical observations and results of in vitro experimental studies indicate that in men, trichomoniasis has been also associated with infertility through inflammatory damage to the genitourinary tract or interference with sperm function.

CONCLUSION

These results contribute significantly to improving our knowledge of the role of parasitic virulence factors in the development of infection and its role in human infertility.

A review of sexually transmitted bovine trichomoniasis and campylobacteriosis affecting cattle reproductive health

The objective is to discuss sexually transmitted diseases caused by Tritrichomonas foetus (T foetus) and Campylobacter fetus (C fetus) subsp. venerealis, with a focus on prevalence, pathogenesis, and diagnosis in cows and bulls. Diagnosis and control are problematic because these diseases cause severe reproductive losses in cows, but in bulls are clinically asymptomatic, which allows the disease to flourish, especially in the absence of legislated control programs. We review research regarding prophylactic systemic immunization of bulls and cows with antigens of T foetus and C fetus venerealis and their efficacy in preventing or clearing preexisting infections in the genital tract. Current diagnostic methods of C fetus venerealis and T foetus (microbial culture and PCR) should be improved. Review of the latest advances in bovine trichomoniasis and campylobacteriosis should promote knowledge and provide an impetus to pursue further efforts to control bovine sexually transmitted diseases.

Immunity in urogenital protozoa

Innate and adaptive immunity play a significant role in urogenital infections. Innate immunity is provided by the epithelial cells and mucus lining along with acidic pH, which forms a strong physical barrier against the pathogens in female reproductive tract. Cells of innate immune system, antimicrobial peptides, cytokines, chemokines and adaptive immunity in the reproductive tract are evolved during infection, and a pro-inflammatory response is generated to fight against the invading pathogen Trichomonas vaginalis, a primary urogenital protozoa, the etiological agent of human trichomoniasis, a curable sexually transmitted infection. The involvement of the urogenital tract by other protozoal infections such as P. falciparum, Trypanosoma, Leishmania, Toxoplasma, Entamoeba histolytica and Acanthamoeba infection is rarely reported. Trichomonas induce pro-inflammatory and immunosuppressive responses in infected subjects. Multifactorial pathogenic mechanisms including parasite adherence, cysteine proteases, lipophosphoglycan, free radical, cytokine generation and Toll-like receptors appear to interplay with the induction of local and systemic immune responses that ultimately determine the outcome of the infection. However, the involvement of urogenital pathogen-specific immune mechanisms and effect of normal local resident flora on the outcome (symptomatic vs. asymptomatic) of infection are poorly understood. Moreover, immune interactions in trichomoniasis subjects co-infected with bacterial and viral pathogens need to be elucidated.

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.

Unlocking the secrets of multi-flagellated propulsion: drawing insights from Tritrichomonas foetus

In this work, a high-speed imaging platform and a resistive force theory (RFT) based model were applied to investigate multi-flagellated propulsion, using Tritrichomonas foetus as an example. We discovered that T. foetus has distinct flagellar beating motions for linear swimming and turning, similar to the 'run and tumble' strategies observed in bacteria and Chlamydomonas. Quantitative analysis of the motion of each flagellum was achieved by determining the average flagella beat motion for both linear swimming and turning, and using the velocity of the flagella as inputs into the RFT model. The experimental approach was used to calculate the curvature along the length of the flagella throughout each stroke. It was found that the curvatures of the anterior flagella do not decrease monotonically along their lengths, confirming the ciliary waveform of these flagella. Further, the stiffness of the flagella was experimentally measured using nanoindentation, allowing for calculation of the flexural rigidity of T. foetus's flagella, 1.55×10(-21) N m(2). Finally, using the RFT model, it was discovered that the propulsive force of T. foetus was similar to that of sperm and Chlamydomonas, indicating that multi-flagellated propulsion does not necessarily contribute to greater thrust generation, and may have evolved for greater manoeuvrability or sensing. The results from this study have demonstrated the highly coordinated nature of multi-flagellated propulsion and have provided significant insights into the biology of T. foetus.

Trichomoniasis: the "neglected" sexually transmitted disease

Trichomonas vaginalis is the most prevalent nonviral sexually transmitted infection, affecting an estimated 3.7 million people in the United States. Although trichomoniasis is common, it has been considered a "neglected" sexually transmitted disease, due to limited knowledge of its sequelae and associated costs. This article reviews current epidemiology, pathophysiology, diagnostic methods, clinical management recommendations and special considerations, research on associated conditions and costs, prevention strategies, and controversies regarding trichomoniasis.

TvMP50 is an immunogenic metalloproteinase during male trichomoniasis

Trichomonas vaginalis, a human urogenital tract parasite, is capable of surviving in the male microenvironment, despite of the presence of Zn(2+). Concentrations > 1.6 mM of Zn(2+) have a trichomonacidal effect; however, in the presence of ≤1.6 mM Zn(2+), several trichomonad proteins are up- or down-regulated. Herein, we analyzed the proteome of a T. vaginalis male isolate (HGMN01) grown in the presence of Zn(2+) and found 32 protein spots that were immunorecognized by male trichomoniasis patient serum. Using mass spectrometry (MS), the proteins were identified and compared with 23 spots that were immunorecognized in the proteome of a female isolate using the same serum. Interestingly, we found a 50-kDa metallopeptidase (TvMP50). Unexpectedly, this proteinase was immunodetected by the serum of male trichomoniasis patients but not by the female patient serum or sera from healthy men and women. We analyzed the T. vaginalis genome and localized the mp50 gene in locus TVAG_403460. Using an RT-PCR assay, we amplified a 1320-bp mp50 mRNA transcript that was expressed in the presence of Zn(2+) in the HGMN01 and CNCD147 T. vaginalis isolates. According to a Western blot assay, native TvMP50 was differentially expressed in the presence of Zn(2+). The TvMP50 proteolytic activity increased in the presence of Zn(2+) in both isolates and was inhibited by EDTA but not by ptosyl-L-lysine chloromethyl ketone (TLCK), E64, leupeptin, or phenylmethane sulfonyl fluoride. Furthermore, the recombinant TvMP50 had proteolytic activity that was inhibited by EDTA. These data suggested that TvMP50 is immunogenic during male trichomoniasis, and Zn(2+) induces its expression.

Trichomonas vaginalis pathobiology new insights from the genome sequence

The draft genome of the common sexually transmitted pathogen Trichomonas vaginalis encodes one of the largest known proteome with 60,000 candidate proteins. This provides parasitologists and molecular cell biologists alike with exciting, yet challenging, opportunities to unravel the molecular features of the parasite's cellular systems and potentially the molecular basis of its pathobiology. Here, recent investigations addressing selected aspects of the parasite's molecular cell biology are discussed, including surface and secreted virulent factors, membrane trafficking, cell signalling, the degradome, and the potential role of RNA interference in the regulation of gene expression.

Pseudocyst forms of Trichomonas vaginalis from cervical neoplasia

Trichomonas vaginalis, a flagellated protozoan parasite causes a variety of adverse health consequences in both men and women. The parasite exists in the trophozoite and the pseudocystic stage. The study reports for the first time that pseudocyst forms of T. vaginalis isolated from cervical neoplasia (CN) patients demonstrated distinct, different and significant in vitro growth profiles when grown in vitro cultures from day 1 up to day 5 (p<0.05, Mann-Whitney test) when compared with the same life cycle stages isolated from non-cervical neoplasia but symptomatic patients (NCN). Pseudocysts from CN and NCN isolates remained viable in distilled water until 3 h 10 min and 2 h 10 min, respectively. The nucleus of pseudocysts in CN isolates using acridine orange and DAPI showed more intense staining revealing higher nuclear content. The FITC-labeled Concanavalin A stained stronger green fluorescence with surface of pseudocysts in CN isolates showing more rough and creased surface with higher numbers of deep micropores with larger numbers of chromatin masses, vacuoles, and hydrogenosomes. The study confirms that pseudocystic stage from CN, despite the uniformity in appearance of being rounded and showing no motility without a true cyst wall under light microscopy, demonstrated different biochemical, surface, and ultrastructural properties. The study provides evidence that phenotypic variant forms of pseudocysts does exist and possibly does play a role in exacerbating cervical cancer.

The Effect of Commiphora molmol (Myrrh) in Treatment of Trichomoniasis vaginalis infection

BACKGROUND

Trichomoniasis vaginalis is now an important worldwide health problem. Metronidazole has so far been used in treatment, but the metronidazole-resistant strains and unpleasant adverse effects have been de-veloped. Myrrh is one of the oldest known medicinal plants used by the ancient Egyptians for medical purposes and for mummification. Commiphora molmol (Myrrh) proved safe for male reproductive organ which is the main habitat of T. vaginalis and this study aims to evaluate the efficacy of the herbal against T. vaginalis in females.

METHODS

In the present study, 33 metronidazole-resistant T. vaginalis females were treated with a combined course of metronidazole and tinidazole. Those still resistant to the combined treatment were given C. molmol. Also, natural plant extract purified from pomegranate (Punica granatum, Roman) was in-vitro investigated for its efficacy against T. vaginalis on Diamond media.

RESULTS

The anti-T. vaginalis activity of both P. granatum (in-vitro) and C. molmol (in-vivo) extracts gave promis-ing results.

CONCLUSION

The anti-T. vaginalis activity of P. granatum and C. molmol showed promising results indicating to sources of new anti-Ttrichomonas agents.

Male accessory gland infection and sperm parameters (review)

Male accessory gland infection (MAGI) has been identified among those diagnostic categories which have a negative impact on the reproductive function and fertility in males (Rowe et al., World Health Organization Manual for the Standardised Investigation and Diagnosis of the Infertile Couple, Cambridge University Press, Cambridge, 1993). MAGI is a hypernym which groups the following different clinical categories: prostatitis, prostate-vesiculitis and prostate-vesiculo-epididymitis. Some of the characteristics they share are: common diseases, mainly have a chronic course, rarely cause obstruction of the seminal pathways, can have an unpredictable intracanicular spread to one or more sexual accessory glands of the reproductive tract, as well as to one or both sides. In this review, we show that all components involving the inflammatory response (from the agents which first trigger it to each component of the inflammatory response dynamic) can deteriorate conventional and/or non-conventional sperm parameters arising from one or more of the following mechanisms: altered secretory function of the epididymis, seminal vesicles, and prostate which reduce the antioxidant properties or scavenging role of the seminal plasma; deterioration of spermatogenesis; and (unilateral or bilateral) organic or functional sub-obstruction of the seminal tract.

Immunity to infections in the lower genital tract of bulls

The mucosa of the bovine prepuce has unique immunological characteristics critical to defense against sexually transmitted diseases. Tritrichomonas foetus and Campylobacter fetus subspecies venerealis persistently colonize the lower genital tract of bulls but usually do not cause either major clinical signs or inflammation. These microbes may be sexually transmitted to female cattle to cause reproductive failure. Although the male genital immune responses to T. foetus and C. fetus subspecies venerealis are inefficient in clearing infection, systemic immunization with T. foetus and C. fetus subspecies venerealis antigens does prevent or eliminate these infections with induction of IgG antibodies in genital secretions and serum.

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.

Impact of T. vaginalis infection on innate immune responses and reproductive outcome

Trichomonas vaginalis is the most common non-viral sexually transmitted pathogen. The infection is prevalent in reproductive age women and is associated with vaginitis, endometritis, adnexitis, pyosalpinx, infertility, preterm birth, low birth weight, bacterial vaginosis, and increased risk of cervical cancer, HPV, and HIV infection. In men, its complications include urethritis, prostatitis, epididymitis, and infertility through inflammatory damage or interference with the sperm function. The infection is often asymptomatic and recurrent despite the presence of specific antibodies, suggesting the importance of the innate immune defense. T. vaginalis adhesion proteins, cysteine proteases, and the major parasite lipophosphoglycan (LPG) play distinct roles in the pathogenesis and evasion of host immunity. LPG plays a key role in the parasite adherence and signaling to human vaginal and cervical epithelial cells, which is at least in part mediated by galectins. The epithelial cells respond to T. vaginalis infection and purified LPG by selective upregulation of proinflammatory mediators. At the same time, T. vaginalis triggers an immunosuppressive response in monocytes, macrophages, and dendritic cells. The molecular mechanisms underlying reproductive complications and epidemiologic risks associated with T. vaginalis infection remain to be elucidated.

Trichomonas vaginaliskills and eats – evidence for phagocytic activity as a cytopathic effect

This study reports that the cytopathic effect ofTrichomonas vaginalis, an important human parasite of the urogenital tract, occurs due to mechanical stress and subsequent phagocytosis of the necrotic cells. The investigation was done using a primary culture of bovine oviduct epithelial cells (BOECs), grown either in monolayers or as floating cells. Trophozoites displaying different virulence levels were co-incubated with BOECs for times varying between 1 min and 48 h. Analyses were performed using videomicroscopy, scanning and transmission electron microscopy, colourimetric assays and cytochemistry. Injury was observed as early as 1 h after incubation, while after 12 h the host cells were severely damaged when a fresh trichomonad isolate was used. Trichomonads attack the host cells by clustering around them. Mechanical stress on the microvilli of the host cells was observed and appeared to induce plasma membrane damage and cell death. After membrane injury and lysis, fragments of the necrotic cells were ingested by trichomonads. Phagocytosis occurred by trichomonads avidly eating large portions of epithelial cells containing the nucleus and other organelles, but living or intact cells were not ingested. Necrotic fragments were rapidly digested in lysosomes, as shown by acid phosphatase and ruthenium red assays where only the BOECs were labelled. The lytic capacity of the trichomonads was more pronounced in host cell suspensions.

Comparative analysis of trichomonad genome sizes and karyotypes

In parasitic protists, the genome sizes range from 2.9Mb in Encephalitozoon cuniculi to about 160Mb in Trichomonas vaginalis. The suprisingly large genome size of the former human parasite resulted from the expansion of various repetitive elements, specific gene families, and possibly from large-scale genome duplication. The reason for this phenomenon, as well as whether other trichomonad species have undergone a similar genome expansion, is not known. In this work we studied the genomes of nine selected species of the Trichomonadea group. We found that each species has a characteristic karyotype with a stable and haploid number of chromosomes. Relatively large genome sizes were found in all the tested species, although over a rather broad range (86-177Mb). The largest genomes were typically observed in the Trichomonas and Tritrichomonas genera (133-177Mb), while Tetratrichomonas gallinarum contains the smallest genome (86Mb). The genome size correlated with the cell volume, however, no relationship between genome size and the site of infection or trichomonad phagocytic ability was observed. The data presented here provide primary information towards selecting a trichomonad species for future large-scale sequencing to elucidate the evolution of unusual parabasalid genomes.