Analysis of surface saccharides in Trichomonas vaginalis strains with various pathogenicity levels by fluorescein-conjugated plant lectins

Latent Upregulation of Nlrp3, Nlrc4 and Aim2 Differentiates between Asymptomatic and Symptomatic Trichomonas vaginalis Infection

Trichomonas vaginalis is a parasitic protozoan that causes trichomoniasis. The involvement of NLRP3 inflammasome in trichomoniasis has been discussed in recent studies. The present study aimed to find out the involvement of Nlrp3, Nlrc4, and Aim2 in the BALB/c mouse model infected with symptomatic and asymptomatic isolates of T. vaginalis by quantitative real-time PCR and immunohistochemistry. Our results showed a significantly increased expression of Nlrp3 in the vaginal tissue of the symptomatic group on the 2^nd dpi and 14^th dpi in the asymptomatic group, respectively. The cervical tissue of asymptomatic groups expressed higher Nlrp3 on 14^th dpi than the symptomatic group. The Nlrc4 was expressed on 14^th dpi in the vaginal and cervical tissues of mice infected with asymptomatic group as compared to the symptomatic group. Aim2 expression in vaginal tissue was highest at early time points in both the infected groups as compared to controls. However, in cervical tissues, a significant increase of Aim2 expression was observed on 14^th dpi in asymptomatic as compared to the symptomatic group. The significantly higher expression of caspase-1 and caspase-4 was observed in cervical tissues of the asymptomatic group on 14^th dpi as compared to the symptomatic group, respectively. All NLRs together resulted in higher IL-1β expression in the vaginal tissues of the symptomatic and asymptomatic groups. We conclude from this study that early expression of Nlrp3, Nlrc4, and Aim2 was seen in the symptomatic group as compared to the late-onset asymptomatic in the vaginal and cervical tissues.

Variation in the saccharide lectin binding pattern from different isolates of Tritrichomonas foetus

Tritrichomonas foetus (T. foetus) is the causal agent of bovine tritrichomonosis (BT), a venereal disease that causes significant economic losses in the bovine livestock industry. The structural organization of T. foetus presents a cell membrane, an undulating membrane which extends along the parasite, three anterior flagella and a recurrent posterior flagellum. The interaction between the superficial glycoconjugates of the parasite and the host cell is one of the most relevant pathogenic mechanisms. In the present study, we analyzed the saccharide pattern through lectincytochemistry of the cell membrane, undulating membrane, cytoplasm and flagella of 28 isolates of T. foetus. Lectins that labeled most of the isolates were WGA, Con-A, RCA-I, LCA, GS-II and PHA-E showing the presence of D-mannose, D-glucose, N-acetylglucosamine and sialic acid. On the other hand, no labeling was observed in any of the structures with VVA, STA, LEA, Jacalin, GS-I, SJA, PHA-L, DSA, and weak labeling was observed with DBA, PNA, SBA and UEA I, showing therefore a low expression of N-acetylgalactosamine, L-fucose and galactose. In addition, GS II labeled in a granular pattern when lectincytochemistry was positive, whereas LCA strongly labeled the membranes and weakly the cytoplasms. The labeling variations observed among the isolates analyzed in the present work, could be related to differences in the pathogenic behavior of the isolates.

Trichomonas vaginalis contact-dependent cytolysis of epithelial cells

Trichomonas vaginalis is an extracellular protozoan parasite that binds to the epithelium of the human urogenital tract during infection. In this study, we examined the propensities of 26 T. vaginalis strains to bind to and lyse prostate (BPH-1) and ectocervical (Ect1) epithelium and to lyse red blood cells (RBCs). We found that only three of the strains had a statistically significant preference for either BPH-1 (MSA1103) or Ect1 (LA1 and MSA1123). Overall, we observed that levels of adherence are highly variable among strains, with a 12-fold range of adherence on Ect1 cells and a 45-fold range on BPH-1 cells. Cytolysis levels displayed even greater variability, from no detectable cytolysis to 80% or 90% cytolysis of Ect1 and BPH-1, respectively. Levels of adherence and cytolysis correlate for weakly adherent/cytolytic strains, and a threshold of attachment was found to be necessary to trigger cytolysis; however, this threshold can be reached without inducing cytolysis. Furthermore, cytolysis was completely blocked when we prevented attachment of the parasites to host cells while allowing soluble factors complete access. We demonstrate that hemolysis was a rare trait, with only 4 of the 26 strains capable of lysing >20% RBCs with a 1:30 parasite/RBC ratio. Hemolysis also did not correlate with adherence to or cytolysis of either male (BPH-1)- or female (Ect1)-derived epithelial cell lines. Our results reveal that despite a broad range of pathogenic properties among different T. vaginalis strains, all strains show strict contact-dependent cytolysis.

Chemical structure of Trichomonas vaginalis surface lipoglycan: a role for short galactose (β1-4/3) N-acetylglucosamine repeats in host cell interaction

The extracellular parasite Trichomonas vaginalis contains a surface glycoconjugate that appears to mediate parasite-host cell interaction via binding to human galectin-1. This glycoconjugate also elicits cytokine production from human vaginal epithelial cells, implicating its role in modulation of host immune responses. We have analyzed the structure of this glycoconjugate, previously described to contain the sugars rhamnose (Rha), N-acetylglucosamine (GlcNAc), galactose (Gal), xylose (Xyl), N-acetylgalactosamine (GalNAc), and glucose (Glc), using gas chromatograph mass spectrometry (GC-MS), matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF), electrospray MS/MS, and nuclear magnetic resonance (NMR), combined with chemical and enzymatic digestions. Our data reveal a complex structure, named T. vaginalis lipoglycan (TvLG), that differs markedly from Leishmania lipophosphoglycan and Entamoeba lipopeptidophosphoglycan and is devoid of phosphosaccharide repeats. TvLG is composed of an α1–3 linked polyrhamnose core, where Rha residues are substituted at the 2-position with either β-Xyl or chains of, on average, five N-acetyllactosamine (-3Galβ1–4GlcNAcβ1-) (LacNAc) units and occasionally lacto-N-biose (-3Galβ1-3GlcNAcβ1-) (LNB). These chains are themselves periodically substituted at the Gal residues with Xyl-Rha. These structural analyses led us to test the role of the poly-LacNAc/LNB chains in parasite binding to host cells. We found that reduction of poly-LacNAc/LNB chains decreased the ability of TvLG to compete parasite binding to host cells. In summary, our data provide a new model for the structure of TvLG, composed of a polyrhamnose backbone with branches of Xyl and poly-LacNAc/LNB. Furthermore, the poly-LacNAc side chains are shown to be involved in parasite-host cell interaction.

Kinetics of immunoglobulin G, M, A and IgG subclass responses in experimental intravaginal trichomoniasis: prominence of IgG1 response

Trichomoniasis, the most common nonviral sexually transmitted disease, is caused by infection with the protist Trichomonas vaginalis. The clinical spectrum varies from an asymptomatic state to mild, moderate or severe symptoms. However, the exact factors leading to varied symptomatology have not been well elucidated. The mouse is a useful experimental model for intravaginal trichomoniasis, for understanding the role of local immune responses in the pathogenesis and varied symptomatology of this disease. The present study reports anti-Trichomonas IgG, IgM, IgA and IgG subclass antibody responses on different post-infection days (3rd, 7th, 14th, 21st and 28th) in serum and vaginal washes of mice infected intravaginally with T. vaginalis isolates from 15 symptomatic and 15 asymptomatic women. Successful intravaginal infection was established by inoculating T. vaginalis in BALB/c mice pre-inoculated with Lactobacillus acidophilus and pretreated with oestradiol. A significant increase in parasite load was observed on the 14th post-infection day (p.i.d.) in mice inoculated with T. vaginalis isolates from symptomatic women as compared to asymptomatic women (P < 0.001), followed by reduction until the 28th p.i.d. (P < 0.05). A significant increase in specific IgG (P < 0.001) and in particular IgG1 (P < 0.001) and IgM (P < 0.01) responses was observed on the 14th p.i.d. in serum and vaginal washes of mice infected with T. vaginalis isolates from symptomatic women as compared to asymptomatic women. Significant increases in specific IgG, IgM and IgG1 responses was observed on the 14th p.i.d. in serum samples as compared with vaginal washes of mice infected with T. vaginalis isolates from symptomatic and asymptomatic women (P < 0.01), whereas no significant difference was observed in IgA, IgG2a, IgG2b and IgG3 antibody responses. The study indicates that specific IgG, particularly IgG1 and IgM, may be playing a role in establishing symptomatic infection.

Reactive nitrogen intermediates in experimental trichomoniasis induced with isolates from symptomatic and asymptomatic women

Trichomoniasis is the interplay between the infecting parasite, Trichomonas vaginalis, and the host, on which the clinical presentation of the disease depends. Although the clinical spectrum varies from an asymptomatic state to mild, moderate or severe symptoms, the exact virulence markers of T. vaginalis have not been well elucidated. Free radical generation during the disease process and its role in pathogenesis has been reported in various microbial diseases. In the present study, an attempt has been made to study reactive nitrogen intermediate (RNI) concentrations in experimental animals infected with T. vaginalis isolates from symptomatic and asymptomatic women. A significant increase in polymorphs, vaginal epithelial cells and RNI levels was observed in mice infected with isolates from symptomatic and asymptomatic subjects as compared to uninfected controls. The mean concentration of RNI in the vaginal tissue of mice infected with isolates from symptomatic women (75.5+/-7.7) was significantly higher than that of the vaginal tissue of mice infected with isolates from asymptomatic women (47.9+/-7.8), while it was less in the vaginal washes and plasma of mice infected with isolates from symptomatic women (18.7+/-3.6 and 17.1+/-3.3, respectively) compared to those infected with isolates from asymptomatic women (28.9+/-7.3 and 26.7+/-4.4, respectively), which may be due to different macrophage populations with different functional capabilities. Our study indicates that RNI production may play a role in establishing the infection.

Trichomonas vaginalis interactions with fibronectin and laminin

The sexually transmitted protozoan Trichomonas vaginalis cytoadheres to vaginal epithelial cells and causes contact-dependent cytotoxicity which, when combined with the normal exfoliation process, leads to erosion of the epithelium, which may allow trichomonads into extracellular matrix and basement membrane sites. Therefore, the association of T. vaginalis with immobilized fibronectin (FN) and laminin (LM) on cover-slips was examined. Binding of live parasites to coated cover-slips was time- and parasite-density-dependent. Coincubation with an inhibitor of trichomonad cysteine proteinases resulted in an increased attachment of parasites to FN but had no effect on binding to LM, denoting that protease activity influenced optimal FN associations. Further, 20 h mid-exponential phase trichomonads placed in fresh culture medium for 3 h gave higher levels of binding to FN, suggesting that changes during growth in vitro to T. vaginalis organisms affect maximal levels of binding to FN. Extended incubation with substrates diminished the capacity of parasites to bind FN and LM. Treatment of live organisms with periodate reduced binding to LM but not FN, suggesting a role for carbohydrates. In addition, trypsinization of live parasites decreased numbers bound to both substrates. Placement of trypsinized parasites in medium for 2 h fully regenerated binding to FN but not LM. Incubation of trypsinized parasites with cycloheximide abrogated regeneration of attachment to FN, affirming a role for synthesized surface proteins in FN binding. Importantly, the T. vaginalis adhesin proteins that mediate cytoadherence, and iron, a factor that regulates adhesin synthesis, were not involved in FN and LM recognition. These results suggest a role for surface proteins and carbohydrates in trichomonal associations with FN and LM, respectively.

Clinical and microbiological aspects of Trichomonas vaginalis

Trichomonas vaginalis, a parasitic protozoan, is the etiologic agent of trichomoniasis, a sexually transmitted disease (STD) of worldwide importance. Trichomoniasis is the most common nonviral STD, and it is associated with many perinatal complications, male and female genitourinary tract infections, and an increased incidence of HIV transmission. Diagnosis is difficult, since the symptoms of trichomoniasis mimic those of other STDs and detection methods lack precision. Although current treatment protocols involving nitroimidazoles are curative, metronidazole resistance is on the rise, outlining the need for research into alternative antibiotics. Vaccine development has been limited by a lack of understanding of the role of the host immune response to T. vaginalis infection. The lack of a good animal model has made it difficult to conduct standardized studies in drug and vaccine development and pathogenesis. Current work on pathogenesis has focused on the host-parasite relationship, in particular the initial events required to establish infection. These studies have illustrated that the pathogenesis of T. vaginalis is indeed very complex and involves adhesion, hemolysis, and soluble factors such as cysteine proteinases and cell-detaching factor. T. vaginalis interaction with the members of the resident vaginal flora, an advanced immune evasion strategy, and certain stress responses enable the organism to survive in its changing environment. Clearly, further research and collaboration will help elucidate these pathogenic mechanisms, and with better knowledge will come improved disease control.

Carbohydrate involvement in the association of a prokaryotic cell with Trichomonas vaginalis and Tritrichomonas foetus

Previous studies have shown that Trichomonas vaginalis are capable of ingesting bacteria. This observation was confirmed in the present study and extended to Tritrichomonas foetus. Using a special strain of Escherichia coli grown under conditions that produced fimbriae presenting a lectin-like molecule recognizing mannose, we showed that the bacteria attached to and were ingested by trichomonads through a mechanism involving cell-to-cell recognition. Absence of the fimbriae or addition of alpha-methyl-D-mannoside to the interaction medium blocked attachment of the bacteria to the protozoa cell surface. Ingested bacteria were later digested within the cytoplasmic vacuole.

Lipophosphoglycan-like glycoconjugate of Tritrichomonas foetus and Trichomonas vaginalis

Lipophosphoglycan-like glycoconjugates were isolated, purified and partially characterized from Tritrichomonas foetus and Trichomonas vaginalis. Cell surface radiolabeling of both trichomonads by the galactose oxidase/NaB[3H]4 technique indicated that the glycoconjugate was located on the cell surface of the parasites. The glycoconjugates were extracted from the delipidated residue fraction with the solvent, water/ethanol/diethylether/pyridine/NH4OH (15:15:5:1:0.017) and were purified to homogeneity by Sepharose CL-4B followed by octyl-Sepharose chromatography and methanol precipitation. The glycoconjugates migrated as broad bands upon SDS-PAGE. The T. foetus glycoconjugate contained large amounts of fucose along with some mannose, galactose, glucosamine and glucose and trace amounts of galactosamine and inositol. The T. vaginalis glycoconjugate appeared to contain large amounts of glucosamine and galactose along with some glucose, mannose and traces of galactosamine and inositol. The surface-labeled glycoconjugates from both parasites was found to be deaminated with nitrous acid and susceptible to phosphatidylinositol-specific phospholipase C, indicating the presence of a phospholipid anchor. Furthermore, these glycoconjugate were found to contain phosphate and were labile to hydrolysis by mild acid, strongly suggesting that the intact molecule is related to Leishmania lipophosphoglycans (LPG). The most striking and the unique features of these glycoconjugate molecules are the presence of large amounts of fucose in T. foetus and glucosamine in T. vaginalis along with the presence of galactosamine in both parasites. These results indicate that these glycoconjugates are new types of LPG-like molecules expressed on the trichomonad cell surface and are structurally distinct from Leishmania LPG.

Trichomonas vaginalis: strain differences in adhesion to plastic and virulence in vitro and in vivo

Trichomonas vaginalis isolated from clinical cases were grown axenically in TYI-S-33 medium. Various strains of this flagellate showed different adhesion characteristics in medium containing bovine serum or Cohn fractions thereof. These were not inversely related to the time in axenic culture. The adsorption of serum components to the parasites was assessed in relationship to adhesion but in many cases was probably not adhesion-related. All strains tested for virulence in vitro were almost equally cytotoxic for HeLa tissue cultures. However, in infectivity trials, one of these strains exhibited the highest adhesion capability and proved to be the most virulent for mice, and another (cloned) strain with the poorest adhesion capability failed to cause infection. Other strains exhibited lessened virulence following their extended axenic cultivation. It therefore appears that the in vivo pathogenic potential of the parasites growing in axenic culture is inherently strain-dependent. The findings suggest that although adhesion in whole serum-containing medium is sufficient to differentiate between various Trichomonas isolates, it is insufficiently sensitive to correlate adhesion with virulence. It apparently is important to identify the adhesion-mediating factor(s) in serum or in its Cohn fractions IV-1 and IV-4 and to use it (them) to elucidate the possible correlation between the parasite's capacity to adhere and its pathogenicity.

Effect of a phorbol ester on basic surface properties of trichomonads

The effect of nanomolar concentrations of 12-O-tetradecanoilphorbol-13-acetate (TPA) on the cell surface of the urogenital parasitic protozoa Trichomonas vaginalis and Tritrichomonas foetus was evaluated by means of measurements of the parasites' surface tension, electrokinesis, lectin agglutination tests, and adhesion to inert substrates. TPA-treated parasites had their adhesion increased to both plastic and glass substrates. This was accompanied by increases in the parasites' net negative surface charge and also by changes in their surface tension. The lectin agglutination assays suggest that the increase in surface negativeness may be related in some extent to alterations in the oligosaccharide composition. Successive treatment of the microorganisms with TPA and sphingosine, a well-known competitive inhibitor of the phorbol ester active site, depressed the tendency of trichomonads to exhibit a phenotype of activated cells.

A cytopathic effect of Trichomonas vaginalis probably mediated by a mannose/N-acetyl-glucosamine binding lectin

The pathogenic effect of a highly pathogenic strain of Trichomonas vaginalis on McCoy cell monolayers was investigated. Specific inhibition of the cytopathic effect by monosaccharides, such as N-acetyl-glucosamine (GlcNAc) and mannose (Man), was observed. Our preliminary results suggest that the pathogenicity of T. vaginalis depends on a lectin specifically sensitive to GlcNAc and to a lesser extent to Man. Although N-acetyl-mannosamine was found to be the most efficient inhibitor, this effect seems to be unrelated to the natural biological behaviour of the infested host.

In vitro phagocytic interaction between Trichomonas vaginalis isolates and bacteria

The phagocytic activity of 12 Trichomonas vaginalis isolates against both gram-positive bacteria (Staphylococcus aureus ATCC 25923, Lactobacillus spp.) and gram-negative bacteria (Enterobacter cloacae ATCC 13047, 5 strains of Escherichia coli, Pseudomonas aeruginosa ATCC 27853) was studied. Results showed that all the isolates were able to ingest Staphylococcus aureus to a variable degree, and almost all of them showed phagocytic activity against Pseudomonas aeruginosa. Furthermore, experiments with a restricted number of isolates of Trichomonas vaginalis showed that they phagocytized, often very effectively, human vaginal lactobacilli. Only in some cases was the addition of serum essential for bacteria ingestion. Phagocytic uptake of Escherichia coli and Enterobacter cloacae was not detectable under the experimental conditions used. It is concluded that phagocytosis may be involved in changes in vaginal biocenosis during the early stages of trichomoniasis.

Inhibition of Trichomonas vaginalis motility by monoclonal antibodies is associated with reduced adherence to HeLa cell monolayers

Adherence of trichomonads to host epithelial cells appears to be a critical step in the pathogenesis of trichomoniasis. We evaluated the effect of a panel of 10 monoclonal antibodies on attachment of [35S]methionine-radiolabeled Trichomonas vaginalis strains to HeLa cell monolayers. Of 10 monoclonal antibodies, 3 totally eliminated motility of PHS2J strain trichomonads and reduced their adherence to 48 to 60% of control values (P less than 0.001). However, none of the monoclonal antibodies affected motility or adherence of STD13 strain trichomonads. Although the antibodies all reacted with PHS2J trichomonads by immunofluorescence, there was no correlation between inhibition of adherence and findings on either immunofluorescence or radioimmunoprecipitation. Direct microscopic observations showed that incubation with the monoclonal antibodies did not cause cytolysis of T. vaginalis. In quantitative cultures there was no difference in the number of colonies produced by parasites that had been incubated with antibodies that inhibited or had no effect on adherence. We conclude that our monoclonal antibodies reduced adherence not by cytotoxic effects or by competing for specific sites mediating adherence of the protozoa, but by inhibiting motility of T. vaginalis.

Differential susceptibility of fresh Trichomonas vaginalis isolates to complement in menstrual blood and cervical mucus

The ability of complement in human menstrual blood and cervical mucus to kill Trichomonas vaginalis was compared with that of complement in serum, and 95 fresh trichomonal isolates obtained from vaginal wash material were evaluated for susceptibility to complement immediately after isolation. Only serum and menstrual blood with haemolytic activity produced total cytolysis of T vaginalis. The cytolytic abilities of these fluids were totally inactivated by treatment with heat or edetic acid (EDTA), which confirms the role of complement in cytolysis. Most cervical mucus samples had no detectable trichomonal cytotoxic properties. The cytotoxic activity in the remaining samples was not due to complement, as it was heat stable. Fresh isolates of T vaginalis and subpopulations of fresh isolates differed in their susceptibility or resistance to complement mediated lysis in serum. Resistance to complement did not remain stable after trichomonads were grown in vitro.

Polysaccharide and glycolipid composition in Tritrichomonas foetus

1. The polysaccharide and glycolipid composition in Tritrichomonas foetus was studied by paper, thin-layer and gas-liquid chromatographic analysis. 2. The carbohydrate components of the polysaccharide were glucose (47%), galactose (34%) and mannose (19%). N-acetylneuraminic acid was the sialic acid derivative characterized in the flagellate whole cells. 3. The sialic acid density was estimated as 2.7 x 10(7) residues/cell. 4. The long-chain base dihydrosphingosine, the carbohydrates galactose (67%), glucose (21%) and mannose (12%) as well as the fatty acids myristic (48%) and palmitic (52%) acids were characterized as components of the total glycolipids of T. foetus. 5. Total glycolipids were fractionated: a galactocerebroside and a ganglioside were identified.

Quantitation of concanavalin A and wheat germ agglutinin binding by two strains of Trichomonas vaginalis of differing pathogenicity using gold particle-conjugated lectins

Two strains of Trichomonas vaginalis, which differed in their pathogenicity for both women and experimental animals hosts, were compared for the presence and number of concanavalin A (ConA)- and wheat germ agglutinin (WGA)-binding sites on their surface using gold lectin conjugates. Both strains showed a high affinity for ConA and WGA and a similar pattern of gold particle distribution on the surface coat. The gold marker was distributed over the cytoplasmic membrane sparsely as single particles but more often in groups, suggesting the presence of single and clustered sugar residues on the parasite surface. Statistical analysis of the level of lectin binding, expressed as the number of gold particles attached per 1 micron plasmalemma, by pathogenic and non-pathogenic strains of T. vaginalis show that these two strains do not differ in the number of ConA receptors on their surfaces. However, WGA-binding receptors were more numerous on the surface of the pathogenic than on the non-pathogenic strain. This suggests that these two strains differ in the number of N-acetyl-D-glucosamine residues on their surfaces. The lectin-gold particle conjugate technique therefore appears more sensitive than agglutination assays or the horseradish peroxidase-3,3'-diaminobenzidine method for the assessment of lectin-binding sites on the surface of T. vaginalis.

Trichomonas vaginalis NYH286 phenotypic variation may be coordinated for a repertoire of trichomonad surface immunogens

Trichomonas vaginalis isolate NYH286 was fractionated with immunoglobulin G of sera from patients with trichomoniasis. Subpopulations of trichomonads with phenotypes of either patient serum-immunoglobulin G reactive (PS+) or nonreactive (PS-) were obtained. Flow cytofluorometry of PS+ and PS- subpopulations with a monoclonal antibody called C20A3 which reacts with a high-molecular-weight immunogen of T. vaginalis gave corresponding fluorescent (positive) and nonfluorescent (negative) phenotypes. No relationship was seen between PS+ and PS- phenotypes and binding of soybean agglutinin, wheat germ agglutinin, and concanavalin A, showing that PS- organisms still possessed carbohydrate moieties on their surfaces based on lectin binding. Phenotypic variation among the PS+ and PS- trichomonads was observed during in vitro growth. A positive-to-negative phenotype shift was also recorded for parasites obtained from lesions of mice subcutaneously infected with PS+ trichomonads. The involvement of surface proteins in the differential PS+ and PS- reactions was supported by soluble antigen and whole cell radioimmunoprecipitation assays. Finally, enhanced parasitism and killing of HeLa cells in monolayer cultures were observed for PS- subpopulations as compared with PS+ counterparts. The data support the idea that phenotypic variation for T. vaginalis may be coordinated for a repertoire of trichomonad immunogens and that such membrane dynamics influence expression of virulence determinants for these sexually transmitted disease agents.

The use of a highly sensitive electrophoretic method to compare the proteinases of trichomonads

A highly sensitive electrophoretic method involving gelatin-containing polyacrylamide gels has been used to analyse trichomonad proteinases. Multiple forms, optimally active at pH 5-6, were present in all four species examined, but the species could be distinguished from one another by both quantitative and qualitative differences. The intestinal parasites, Trichomitus batrachorum and Pentatrichomonas hominis, had lower specific activities than the urogenital parasites, Trichomonas vaginalis and Tritrichomonas foetus, and, in the case of P. hominis, there were fewer enzyme forms. The high activity proteinases of Tritrichomonas foetus had low apparent molecular weights (less than 25 kDa), while the predominant enzymes of Trichomonas vaginalis were of high apparent molecular weight (68-110 kDa). Distinct differences were also observed between the proteinase patterns of various isolates of T. vaginalis. All of the enzymes were stimulated by dithiothreitol, suggesting that they were cysteine proteinases. This was confirmed for the T. vaginalis and Tritrichomonas foetus proteinases from their inhibition by antipain, leupeptin, TLCK and iodoacetic acid. The method allows the detection of proteinases in samples of Trichomonas vaginalis containing as few as 10(4) cells or as little as 1 microgram protein. It was also possible to detect proteinase activity released into the medium. For both T. vaginalis and Tritrichomonas foetus, the extracellular enzymes present during early log phase were qualitatively different from the intracellular proteinases, although the latter were present in samples of media obtained from later cultures (cell densities greater than 1 X 10(5) parasites ml-1). The results show the potential of this technique for detecting proteinases in trichomonad samples in studies aimed at determining proteinase function in pathogenesis and host-parasite relationships.

Phenotypic variation and diversity among Trichomonas vaginalis isolates and correlation of phenotype with trichomonal virulence determinants

The extent and nature of heterogeneity among representative Trichomonas vaginalis isolates were evaluated by flow cytofluorometry analysis. Monoclonal antibody and monospecific antiserum to an immunodominant trichomonad surface glycoprotein with a molecular weight of 267,000 (267K glycoprotein) were used to evaluate fresh isolates (JHH and RU375) and long-term grown isolates (NYH286, IR78, and JH31A) of T. vaginalis. Isolates NYH286, JH31A, and JHH were made up of heterogeneous staining (positive [pos] phenotype) and nonstaining (negative [neg] phenotype) populations of trichomonads, whereas RU375 and IR78 were all neg phenotype parasites. Flow cytofluorometric patterns of agar clones derived from single organisms of heterogeneous isolates such as NYH286 showed populations which were either homogeneous pos or neg and also showed clones which were heterogeneous in nature containing both phenotypes. Fluorescence-activated cell sorting was also accomplished, and subpopulations of defined pos or neg phenotype were purified. Flow cytofluorometry evaluation of all isolates for an extended period revealed a phenotypic variation among all heterogeneous isolates and also for all clones and subpopulations derived from the heterogeneous isolates. On the other hand, IR78 and RU375 did not undergo phenotypic variation and have remained neg for greater than 4 years. Parasites which were nonreactive with either monoclonal antibody or monospecific antiserum to the 267K glycoprotein in flow cytofluorometry did not possess the antigen on their surface. This was determined by radioimmunoprecipitation assays using extracts of iodinated trichomonads. Finally, neg phenotype parasites yielded enhanced rates of contact-dependent cytotoxicity of host cell monolayers as compared with the pos phenotype trichomonads.

Further studies on the surface charge of various strains of Trichomonas vaginalis and Tritrichomonas foetus

The surface charge of three strains of Trichomonas vaginalis and five strains of Tritrichomonas foetus was determined by direct measurement of the mean cellular electrophoretic mobility (EPM) of cells suspended in solutions of different ionic strength and pH. No differences were observed in the mean EPM among the two species, although significant differences among the strains exist. Strains that are more pathogenic to mouse, as measured using the subcutaneous assay, had a surface more negative. Treatment of the parasites with trypsin or neuraminidase reduced significantly their mean EPM and increased their isoelectric point. Tritrichomonas foetus was more sensitive to the enzyme treatment than T. vaginalis. Enzyme-treated cells recovered their normal EPM if, after enzyme treatment, they were incubated in fresh culture medium. The recovery process of trypsin-treated cells was inhibited 10-20% by addition of inhibitors of either protein synthesis (puromycin) or N-glycosylation of proteins (tunicamycin) to the incubation medium, suggesting that a cytoplasmic pool of sialoglycoproteins may exist. The recovering of the EPM of T. foetus and T. vaginalis previously treated with neuraminidase was inhibited by puromycin or tunicamycin about 40-50% and 17-30%, respectively. These observations suggest that sialoglycolipids exist on the surface of both parasite species, and that they contribute more to the surface charge of T. vaginalis than to that of T. foetus.

Trichomonas vaginalis: electrophoretic analysis and heterogeneity among isolates due to high-molecular-weight trichomonad proteins

The protein composition of Trichomonas vaginalis isolates was evaluated using one-dimensional and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography. At least two hundred intrinsically labeled and about 30 major extrinsically labeled proteins of molecular weights less than 120,000 were resolved by isoelectric focusing and electrophoresis. In general, long-term grown and fresh isolates of T. vaginalis gave similar fluorograms of the readily detectable proteins. Only a minor variance in a distinct protein was noted among three of the four fresh isolated tested. Labeling with [35S]methionine or 3H-amino acids gave almost identical profiles, ensuring the efficient radiolabeling of trichomonad proteins that dominate quantitatively. Comparative analysis of radioactivity profiles of one-dimensional gels emphasizing the region of high-molecular-weight proteins known to reside in low copy number revealed the presence or absence of the internally synthesized proteins from surfaces of T. vaginalis isolates. Finally, immunoblotting of two-dimensional gels demonstrated the highly immunogenic nature of proteins corresponding to quantitatively dominant molecular weight regions of intrinsically labeled proteins.

Monoclonal antibody to a major surface glycoprotein immunogen differentiates isolates and subpopulations of Trichomonas vaginalis

To produce monoclonal antibodies (MAbs) to highly immunogenic membrane proteins of Trichomonas vaginalis NYH286, the sera of subcutaneously infected BALB/c mice were first monitored for antibody to trichomonad surface proteins. The sera possessed antibody to one major surface protein by 7 days and antibody to numerous other trichomonad membrane proteins by 4 weeks postinfection. A hybridoma was then generated that synthesized an MAb, designated C20A3, which reacted to a parasite-derived glycoprotein possessing a molecular weight of 267,000 (267K glycoprotein). The immunogen corresponded to the single high-molecular-weight immunogenic surface protein recognized by 7-day mouse antisera. The MAb differentiated T. vaginalis isolates by a whole-cell enzyme-linked immunosorbent assay and by indirect immunofluorescence, using either fixed or live organisms. All isolates, however, possessed C20A3-reactive material when tested by enzyme-linked immunosorbent assay, using detergent extracts of the isolates incubated with MAb-coated microtiter well plates. The epitope was accessible to antibody binding on live T. vaginalis organisms expressing the major immunogen, and the 267K glycoprotein was readily removed from the parasite membranes by trypsinizing the intact trichomonads. The antigen incorporated radiolabeled glucose, mannose, and acetate. Also, an unlabeled 267K glycoprotein on nitrocellulose blots was detected by 125I-concanavalin A and 125I-wheat germ agglutinin, confirming the glycoprotein nature of the immunogen. Finally, of seven isolates used in this study, one possessed a cross-reactive 170K, rather than 267K, antigen. The data reinforce the idea that antigenic heterogeneity among T. vaginalis isolates may be a function of the presence or absence of high-molecular-weight glycoprotein immunogens from trichomonal membranes.

Specific nature of Trichomonas vaginalis parasitism of host cell surfaces

The adherence of Trichomonas vaginalis NYH 286 to host cells was evaluated by using monolayer cultures of HeLa and HEp-2 epithelial cells and human fibroblast cell lines. Saturation of sites on HeLa cells was achieved, yielding a maximal T. vaginalis NYH 286-to-cell ratio of two. The ability of radiolabeled NYH 286 to compete with unlabeled trichomonads for attachment and the time, temperature, and pH-dependent nature of host cell parasitism reinforced the idea of specific parasite-cell associations. Other trichomonal isolates (JH31A, RU375, and JHHR) were also found to adhere to cell monolayers, albeit to different degrees, and all isolates produced maximal contact-dependent HeLa cell cytotoxicity. The avirulent trichomonad, Trichomonas tenax, did not adhere to cell monolayers and did not cause host cell damage. Interestingly, parasite cytadherence was greater with HeLa and HEp-2 epithelial cells than with fibroblast cells. In addition, cytotoxicity with fibroblast cells never exceeded 20% of the level of cell killing observed for epithelial cells. Elucidation of properties of the pathogenic human trichomonads that allowed for host cell surface parasitism was also attempted. Treatment of motile T. vaginalis NYH 286 with trypsin diminished cell parasitism. Incubation of trypsinized organisms in growth medium allowed for regeneration of trichomonal adherence, and cycloheximide inhibited the regeneration of attachment. Organisms poisoned with metronidazole or iodoacetate failed to attach to host cells, and adherent trichomonads exposed to metronidazole or iodoacetate were readily released from parasitized cells. Coincubation experiments with polycationic proteins and sugars and pretreatment of parasites or cells with neuraminidase or periodate had no effect on host cell parasitism. Colchicine and cytochalasin B, however, did produce some inhibition of adherence to HeLa cells. The data suggest that metabolizing T. vaginalis adheres to host cells via parasite surface proteins in a specific receptor-ligand fashion. Furthermore, parasitism of epithelial cells appears to render this cell type more susceptible than fibroblast cell types to contact-dependent cytotoxicity.

Identification of a surface antigen of Trichomonas vaginalis

A major surface antigen of Trichomonas vaginalis was purified by using three independently derived monoclonal antibodies (two immunoglobulin M and one immunoglobulin G1) prepared against T. vaginalis PHS-2J. A 115,000-molecular-weight antigen and one or more components with a molecular weight of 58,000 to 64,000 were recovered when any of the three antibodies was used as an immunoadsorbent. The purified antigen reacted with all three monoclonal antibodies in an enzyme-linked immunosorbent assay, indicating that the antibodies recognized the same antigen but not necessarily the same determinant. The purified antigen was sensitive to both pronase digestion and periodate oxidation. The antigen was shown to be on the external surface of some but not all T. vaginalis isolates by agglutination of live organisms with the monoclonal antibodies.

Further studies on the surface saccharides in Trichomonas vaginalis strains by fluorescein-conjugated lectins

Fluorescence emitted by individual cells of several Trichomonas vaginalis strains, nearly all of which were cloned, incubated with fluorescein-conjugated lectins in the absence (experimental) or presence (control) of inhibitory sugars, or else in phosphate-buffered saline alone (autofluorescence) was measured with a Leitz MPV Compact microfluorometer. Irrespective of whether the organisms were postfixed in formalin or glutaraldehyde, the relative fluorescence emitted by the cells was closely comparable, provided that appropriate neutral density filters were employed. However, autofluorescence was much higher for glutaraldehyde-fixed trichomonads. Therefore, although better preserved and more amenable to subsequent manipulations, such organisms were found unsuitable for use in "qualitative" titration of the fluorescence emitted by various strains. Provided that the necessary precautions were taken, comparable fluorescence readings were obtained with trichomonads affixed to glass slides by heat (41 degrees C, on a section spreader) or by a cytologic centrifuge (Cytospin 2). Large numbers of concanavalin A (Con A)-binding sites were present on organisms of all strains, irrespective of their virulence for human patients and as estimated by the subcutaneous mouse assay; these sites were shown with the aid of D-mannose to be mannose or mannose-related residues. More binding sites for soybean agglutinin (SBA) were found on the virulent than on avirulent strains. On the basis of inhibition experiments, the sugar residues mainly responsible for these differences appeared to be D-lactose residues. Similar differences were observed with Ricinus communis agglutinin Type I (RCA I), for which D-galactose was employed as the competing sugar. However, with two cloned strains the situation with regard to RCA I binding was reversed - more of the lectin bound to a mild than to a virulent strain. The results obtained with Ricinus communis Type II agglutinin (RCA II) were often similar to those noted for RCA I; however, in most instances the inhibition with N-acetyl-D-galactosamine (GalNAc) was lower. Furthermore, the results noted with the GalNAc-specific agglutinins from Dolichus biflorus and Helix pomatia suggested that only very few GalNAc residues were available for binding on the surfaces of all T. vaginalis strains examined in the course of this study. Statistical analyses of fluorescence emitted by four clones of each, Balt 42 (virulent) and JH31A (avirulent) T. vaginalis strain upon incubation with Con A and SBA revealed homogeneity of these strains with regard to the number of the specific surface saccharide residues, D-mannose and D-lactose.(ABSTRACT TRUNCATED AT 400 WORDS)

Electrophoretic analysis of soluble proteins and esterase, superoxide dismutase and acid phosphatase isoenzymes of members of the protozoan family trichomonadidae

Polyacrylamide gel electrophoresis was used to compare the proteins and isoenzymes of esterase, superoxide dismutase, and acid phosphatase in soluble, whole-cell extracts of four strains of Trichomonas vaginalis, two strains of Trichomonas gallinae, and one strain each of Tritrichomonas foetus, Tritrichomonas augusta, Tetratrichomonas gallinarum, and Pentatrichomonas hominis. Intraspecific, interspecific, and intergeneric differences were found in protein and isoenzyme profiles. At least four to seven isoenzymes were detected among the ten strains for each of the three enzymes studied. Each strain usually contained one or two isoenzymes of both esterase and acid phosphatase, and two or three isoenzymes of superoxide dismutase.

Binding of concanavalin A and wheat germ agglutinin by murine peritoneal macrophages: Ultrastructural and cytophotometric studies

Concanavalin A and wheat germ agglutinin were employed in conjunction with the horseradish peroxidase-diaminobenzidine method for the detection of sugar residues on the surface coat of exudate and resident murine peritoneal macrophages. Electron microscopical and cytophotometric techniques were used for the visualization and quantification of the final reaction product on the surface of cells. After incubation with concanavalin A and wheat germ agglutinin, both exudate and resident macrophages showed readily detectable final reaction product indicating the presence of numerous, easily accessible, alpha-methyl-D-mannosyl and N-acetyl-D-glucosaminyl residues on their surface. The binding of concanavalin A was higher with resident than with exudate macrophages. With wheat germ agglutinin, a different pattern of lectin binding was observed: more electron-dense product was deposited on exudate than on resident macrophage surfaces. The binding of concanavalin A and wheat germ agglutinin to macrophages was inhibited by the competing sugars alpha-methyl-D-mannoside and N-acetyl-D-glucosamine, respectively.

Comparison of virulence of clones of two Trichomonas vaginalis strains by the subcutaneous mouse assay

No statistical differences in virulence were found among five clones isolated from each of two Trichomonas vaginalis strains JH31A and Balt 42. The former strain, isolated from a patient showing no cervical epithelial abnormalities, caused relatively small subcutaneous lesions in mice [mean volume for the noncloned strain, 75.45 +/- 4.43 mm3 (n = 70); mean of means for cloned populations, 77.28 +/- 3.14 mm3 (n = 230)]. The latter, Balt 42, isolated from a woman with an in situ carcinoma of the cervix uteri, produced large subcutaneous abscesses in mice [mean volume for the noncloned strain, 202.28 +/- 12.53 mm3 (n = 55); mean of means for cloned populations, 200.48 +/- 13.72 mm3 (n = 264)]. The apparent homogeneity of T. vaginalis strains with regard to virulence reinforces the dependability of the subcutaneous mouse assay.

A freeze-fracture electron microscope study of Trichomonas vaginalis Donné and Tritrichomonas foetus (Riedmüller)

Two strains of Trichomonas vaginalis, JH162A , with low pathogenicity, and Balt 44, with high pathogenicity, as well as one highly pathogenic strain, KV-1, of Tritrichomonas foetus were studied by freeze-fracture electron microscopy. The protoplasmic faces ( PFs ) of the cell membranes of all three strains of both species had similar numbers of intramembranous particles (IMPs); however, the particles in the external faces (EFs) of these membranes were least abundant in Trichomonas vaginalis strain Balt 44 and most numerous in those of strain JH162A of this species. In Tritrichomonas foetus strain KV-1 the number of IMPs in the EF was close to but somewhat lower than that in the mild strain of the human urogenital trichomonad . In both species, the anterior, but not the recurrent, flagella had rosette-like formations, consisting of approximately 9 to 12 IMPs on both the PFs and EFs. The numbers and distribution of the rosettes appeared to vary among different flagella and in different areas of individual flagella of a single organism belonging to either species. The freeze-fracture electron micrographs provided a more complete understanding of the fine structure of undulating membranes of Trichomonadinae , as represented by Trichomonas vaginalis, and of Tritrichomonadinae (the Tritrichomonas augusta -type), as exemplified by Tritrichomonas foetus, than was gained from previous transmission and scanning electron microscope studies. Typically three longitudinal rows of IMPs on the PF of the recurrent flagellum of Trichomonas vaginalis were noted in the area of attachment of this flagellum to the undulating membrane. The functional aspects of the various structures and differences between certain organelles revealed in the two trichomonad species by the freeze-fracture method are discussed.

Antigenic analysis of Trichomonas vaginalis strains by quantitative fluorescent antibody methods

Clones of 5 Trichomonas vaginalis strains, JH30A, JH31A, JH34A, JH162A, and JH384A, kept in liquid nitrogen (with DMSO serving as the cryoprotectant) after a few weeks of cultivation in axenic cultures, were analyzed for their antigenic properties by quantitative direct fluorescent antibody methods. Measurements of fluorescence of individual cells obtained with the aid of an ultramicrofluorometer indicated that each strain possessed unique antigens as well as antigens it shared with the other strains studied. The relative amounts of common antigens present in each strain were estimated primarily by calculating the percent of fluorescence reduction recorded for organisms stained with their homologous conjugates, nonadsorbed and adsorbed with the homologous and heterologous antigens (strains). Antigenic relationships among the strains were estimated on the basis of statistical analyses of the data obtained in direct, one-step inhibition, and adsorption staining.