A new method for identification of Trichomonas vaginalis by fluorescent DNA in situ hybridization.

The protozoan flagellate Trichomonas vaginalis is responsible for human trichomoniasis, one of the most widespread sexually transmitted diseases in the world. Several methods are currently used for laboratory diagnosis, including direct microscopic observation, cell culture, immunological techniques, and more recently, DNA probing and gene amplification. This report describes an in situ hybridization technique with specific DNA probes labeled with either biotin, rhodamine, or fluorescein for detection of T. vaginalis with fluorescence microscopy. Repetitive DNA sequences were evident in the nuclei of the protozoa as intensively fluorescent regions, giving a spotted pattern. No cross-reactivity between the probes and the DNAs of mammalian cells, yeasts, or bacteria was noted. This technique is potentially useful for the diagnosis of human trichomoniasis in clinical samples.     

Stability of Trichomonas vaginalis DNA in urine specimens

Trichomonas vaginalis is an important pathogen in both men and women. Culture is considered the diagnostic gold standard, although studies have shown that PCR is more sensitive than either culture or wet mount for the diagnosis of T. vaginalis infections. We sought to identify a simple method for stabilizing T. vaginalis DNA in urine samples that could be easily applied to molecular testing. The stability of T. vaginalis DNA in 40 urine samples was assessed by storage for various times at either 4 degrees C or room temperature with or without the Becton Dickinson urine preservative transport (UPT) kit. Overall, there was better stability of T. vaginalis DNA when specimens were stored at 4 degrees C than when they were stored at 20 to 22 degrees C and when the UPT system was used. T. vaginalis DNA was stable in specimens stored without using the UPT at 4 degrees C for about 3 days and at room temperature for only 1 day. For specimens placed in the UPT within 24 h (times of 1, 6, and 24 h) of collection, the DNA was stable for up to 30 days when stored at 4 degrees C. For specimens stored at room temperature, the urine should be added to the UPT ideally within 1 hour of collection, and in this case the DNA remained stable for up to 30 days. When storing specimens at room temperature, a delay of 24 h prior to adding to UPT led to an unacceptably high loss of assay sensitivity.     

Cloning and characterization of a repetitive DNA sequence specific for Trichomonas vaginalis.

A family of 650-bp-long repeats from the Trichomonas vaginalis genome, designated the Tv-E650 family, was cloned and sequenced. The nucleotide sequence is A+T-rich (73.3% A+T in the consensus sequence) and highly conserved among the 8 molecular clones analyzed. The differences among the clones are single-nucleotide and 2-nucleotide substitutions and insertions or deletions. The sequence uniformity of the clones as well as the presence of identical mutations in different clones suggest that efficient sequence homogenization mechanisms, such as gene conversion or recurring unequal crossing-over, operate in T. vaginalis. The copy number of the Tv-E650 repeats was estimated to be about 10(2)-10(3) per genome. Based on the DNA hybridization results, the Tv-E650 repeat family is conserved in all T. vaginalis strains examined, regardless of their diverse geographical origin. No hybridization of the Tv-E650 probe was found with the DNA from Trichomonas tenax, Trichomonas gallinae and Pentatrichomonas hominis, indicating that the Tv-E650 repeated sequences are species-specific. A dot blot hybridization protocol was developed which does not require isolation of DNA. By using this protocol it was possible to detect the DNA released from approximately 10(3) T. vaginalis cells per dot. These observations suggest that the Tv-E650 probe is potentially applicable to the identification and detection of T. vaginalis.     

Inorganic pyrophosphatase of Trichomonas vaginalis.

Trichomonas vaginalis homogenates were found to have an acid inorganic pyrophosphatase activity with a specific activity at pH 4.8 of about 7 nmol min-1 (mg protein)-1. This activity was localized predominantly in hydrolase containing particles, showed structure-bound latency and was tightly membrane-bound. The activity showed no magnesium dependence, a Km of about 2 mM inorganic pyrophosphate, a pH optimum of 5.2 and was inhibited by fluoride at millimolar levels. No evidence was obtained for the existence of a cytosolic magnesium-dependent activity but the existence of a low level of magnesium-independent cytosolic activity cannot be excluded. These observations correlate with the importance of cytosolic inorganic pyrophosphate in the carbohydrate catabolism in T. vaginalis.     

Monoclonal-antibody-based enzyme-linked immunosorbent assay for Trichomonas vaginalis.

Trichomonas vaginalis is estimated to infect 4 million women per year in the United States. The diagnosis of trichomoniasis is predominantly achieved by direct microscopic examination of vaginal exudates. This subjective diagnostic procedure is reported to be 75% sensitive under ideal circumstances. We have developed an enzyme-linked immunosorbent assay (ELISA) for the detection of T. vaginalis directly from vaginal exudates. The ELISA employs a monoclonal antibody specific for a 65-kilodalton surface polypeptide of T. vaginalis as the capture antibody in a sandwich format. A polyclonal rabbit anti-T. vaginalis antibody labeled with horseradish peroxidase serves as the probe. An evaluation of vaginal specimens from women attending clinics revealed a sensitivity and specificity of the ELISA of 89 and 97%, respectively, versus the culture technique. These results indicate the usefulness of this ELISA as an alternative to microscopic and culture methods for the detection of T. vaginalis in vaginal exudates.     

Guanosine kinase from Trichomonas vaginalis.

A novel guanosine kinase was partially purified from the parasitic protozoan Trichomonas vaginalis. Unlike nucleoside kinases from other sources, the preferred substrate for this enzyme was guanosine (Vmax/Km = 120). The enzyme also catalyzed the phosphorylation of inosine (Vmax/Km = 3), uridine (2), adenosine (0.5), cytidine (0.2), and 2'-deoxyguanosine (0.1). The 2'-deoxyribonucleosides of adenine, hypoxanthine, uracil, cytosine and thymine were not phosphorylated. The Km for ATP was 6.6 microM. The enzyme was extremely labile in the absence of ATP. As a result, only a 20-fold purification with 25% recovery of activity was possible. However, this preparation was free of nucleoside phosphorylase, nucleoside phosphotransferase and the distinct uridine kinase. The enzyme had a broad optimum of pH 6.5-8. It had a molecular weight of 15000.     

Rapid assay for immunological detection of Trichomonas vaginalis.

Trichomoniasis is a common sexually transmitted disease with an estimated incidence of 4 million to 8 million cases a year in the United States. The most commonly used method of diagnosis is a direct microscopic observation (wet mount) of vaginal secretions and, although both rapid and inexpensive, the sensitivity of this technique is generally 50 to 70%. We developed an indirect enzyme-linked immunosorbent assay (ELISA) for the detection of Trichomonas vaginalis which is both rapid and sensitive (detection limit of approximately 100 trichomonads per ml). This assay, which employs affinity-purified rabbit anti-T. vaginalis antibodies in a "sandwich" configuration, is simple to perform and is neither interfered with nor appears to cross-react with other microorganisms which are common inhabitants of the urogenital tract. One hundred and seventy-seven consecutive unselected patients attending a clinic for sexually transmitted diseases were evaluated for trichomoniasis by a broth culture technique monitored for up to 7 days (and considered here to be the standard for positivity), the conventional wet mount method, a solid culture procedure, and the ELISA. Of these, 84 were positive by culture; 33 were positive by the wet mount; and despite the fact that the vaginal specimens were diluted 20-fold during the culture procedures prior to testing in the ELISA, 65 were positive by ELISA. In addition to exhibiting a sensitivity of 77%, the specificity of the ELISA was 100%. These results demonstrate that the ELISA is a significant improvement over the wet mount method for the diagnosis of trichomoniasis.     

Contact-dependent cytopathogenic mechanisms of Trichomonas vaginalis.

The cytopathogenic mechanisms of Trichomonas vaginalis have been debated since the 1940s. We examined the following three proposed pathogenic mechanisms: contact-dependent extracellular killing, cytophagocytosis, and extracellular cytotoxins. Serial observations of Chinese hamster ovary (CHO) cell monolayers exposed to trichomonads revealed that (i) trichomonads form clumps, (ii) the clumps adhere to cells in culture, and (iii) monolayer destruction occurs only in areas of contact with T. vaginalis. Kinetic analysis of target cell killing by trichomonads revealed that the probability of CHO cell death was related to the probability of contact with T. vaginalis, supporting the observation by microscopy that trichomonads kill cells only by direct contact. Simultaneous studies of 111indium oxine label release from CHO cells and trypan blue dye exclusion demonstrated that T. vaginalis kills target cells without phagocytosis. Filtrates of trichomonad cultures or from media in which trichomonads were killing CHO cells had no effect on CHO cell monolayers, indicating that trichomonads do not kill cells by a cell-free or secreted cytotoxin. The microfilament inhibitor cytochalasin D (10 micrograms/ml) inhibited trichomonad killing of CHO cell monolayers by 80% (P less than 0.0001). In contrast, the microtubule inhibitor vinblastine (10(-6) M) caused only 17% inhibition of trichomonad destruction of CHO cell monolayers (P less than 0.020), whereas colchicine (10(-6) M) had no effect. T. vaginalis kills target cells by direct contact without phagocytosis. This event requires intact trichomonad microfilament function; microtubule function appears not to be essential.     

TaqMan-Based Detection of Trichomonas vaginalis DNA from Female Genital Specimens

A double-labeled fluorescent probe was designed and evaluated for detecting Trichomonas vaginalis DNA in a 5' nuclease (TaqMan) assay. The T. vaginalis-specific probe contains a 5'-fluorescein (5'-FAM) and a 3'-rhodamine (TAMRA) derivative. Female genital secretions were collected on Amplicor (Roche Molecular, Indianapolis, Ind.) swabs and by a transport system used for Chlamydia trachomatis and/or Neisseria gonorrhoeae DNA detection by PCR. Five hundred fifty-two female genital specimens, of which 248 (45%) were vaginal specimens and 304 (55%) were introital, were tested for both T. vaginalis DNA and viable microorganisms using the 5' nuclease assay and broth culture, respectively. Of these, 304 of 552 (55%) were also evaluated by direct microscopic examination for the characteristic motile organism. After resolving discrepancies, the comparisons produced an analytical sensitivity and specificity for the TaqMan-based PCR assay of 97.8 and 97.4%, respectively. As a result, DeltaRQ values (differences in fluorescence due to probe hybridization and resulting 5'-FAM cleavage from the specific PCR product) of > or =2.0 and < or =1.5 were established for T. vaginalis-positive and -negative cutoffs, respectively. DeltaRQ values between 1.5 and 2.0 were considered indeterminate. Overall findings revealed a high level of agreement between PCR and culture for detecting T. vaginalis. Potential benefits of the 5' nuclease assay include a greater sensitivity compared to direct microscopic examination and the ease of testing large numbers of clinical specimens in a significantly shorter turnaround time compared to culture.     

Evaluation of affirm VP Microbial Identification Test for Gardnerella vaginalis and Trichomonas vaginalis.

A commercial system (Affirm VP Microbial Identification Test; MicroProbe Corp.) for detection of vaginal pathogens was evaluated with 176 consecutive women attending a sexually transmitted disease clinic for genital complaints. Vaginal swab specimens were used for culture of Gardnerella vaginalis and Trichomonas vaginalis, preparation of a vaginal smear for Gram stain interpretation, and wet mount evaluation. An additional swab was used to evaluate the 30-min nonisotopic oligonucleotide probe test. The automated probe system detected G. vaginalis in 69 (95%) of 73 women having > 5 x 10(5) CFU of G. vaginalis per ml by culture, and 20 (43%) of 47 specimens with < or = 5 x 10(5) CFU of G. vaginalis per ml. There were three false positives and four false negatives for the Affirm VP test compared with > 5 x 10(5) CFU of G. vaginalis per ml. The probe system detected G. vaginalis in 57 (90%) of 63 vaginal specimens from women having clue cells on wet mount examination, and in only 3 (3%) of 113 women without clue cells, suggesting that the Affirm probe for G. vaginalis could be used as a surrogate for wet mount examination for clue cells. The T. vaginalis probe was positive for 12 of 12 specimens positive by wet mount and 12 of 15 specimens positive by culture. There were no false positives and three false negatives for the Affirm VP test compared with culture and/or wet mount for T. vaginalis. The Affirm VP Microbial Identification System is a rapid, objective, and automated test for the detection of T. vaginalis and clinically significant levels of G. vaginalis that is comparable to wet mount examination for clue cells and is superior to wet mount examination for the detection of trichomonads.     

Improved detection by DNA amplification of Trichomonas vaginalis in males

Trichomoniasis is a sexually transmitted infection that is highly prevalent worldwide and has been linked to preterm birth and human immunodeficiency virus acquisition. In females, trichomoniasis causes vaginitis, while in males, it is frequently asymptomatic but can be a cause of urethritis. Control efforts have been hampered by the lack of a sensitive diagnostic technique for this infection in males. Men attending a sexually transmitted disease (STD) clinic for a new complaint were screened for Trichomonas vaginalis by culture and by PCR analysis of urine and urethral-swab specimens. The prevalence of Trichomonas determined by culture was 5% (15 of 300 specimens), compared to 17% (52 of 300) determined by PCR. Urine specimens yielded a greater number of positive results by PCR than did urethral-swab specimens. The sensitivity of PCR analysis of urine specimens in comparison to that of culture was 100%. The use of PCR techniques in urine specimen-based detection of T. vaginalis was highly sensitive and revealed a prevalence of infection more than three times that revealed by culture for men at high risk for STDs.     

Canine prostatic secretions kill Trichomonas vaginalis.

The zinc content of prostatic secretions is thought to be an important nonspecific defense against urinary tract infection in men. This investigation measured killing by prostatic fluid of Trichomonas vaginalis, a common sexually transmitted pathogen, and related this activity to zinc concentration. We used a canine model which closely resembles the human male genital tract. Prostatic secretions from all dogs killed all T. vaginalis isolates. There appear to be several mechanisms for killing of trichomonads by prostatic fluid. At prostatic fluid zinc concentrations comparable to those in normal men (greater than or equal to 3.2 mM), the rate of killing of trichomonads was proportional to the zinc concentration. At intermediate zinc levels, killing occurred by both zinc-dependent and zinc-independent mechanisms. A zinc-independent mechanism was responsible for antitrichomonal activity at relatively low zinc levels (less than 1.6 mM), comparable to those in the prostatic fluid of men with chronic prostatitis. This study suggests that the variable clinical spectrum of trichomoniasis in men may result from a balance between the zinc sensitivity of the T. vaginalis strains on one side and the content of both zinc and zinc-independent factors in prostatic fluid on the other.     

Isolation and characterization of DNA from Tritrichomonas foetus and Trichomonas vaginalis

High molecular weight DNA samples free of contaminating proteins or RNA were obtained from Tritrichomonas foetus or Trichomonas vaginalis by lysing the cells in 4 M guanidinium thiocyanate before centrifuging in CsCl density gradient and then purifying the DNA band by NACS-37 column chromatography. The bulk DNA from either organism acted as a single component in ion-exchange chromatography, agarose gel electrophoresis, CsCl density gradient centrifugation and thermal denaturation. T. foetus DNA showed a melting temperature (Tm) of 82 degrees C corresponding to a 31% GC content whereas T. vaginalis DNA melted at 84 degrees C to suggest 36% GC. Both DNA samples demonstrated 35 to 42% hyperchromicity when fully melted. Cot analysis revealed the presence of repetitive sequences in both DNAs: approximately 46.7% in T. foetus DNA and 53.3% in T. vaginalis DNA. The unique sequences of these two protozoan DNAs are of a similar size of about 2.5 X 10(7) base pairs. Agarose gel electrophoresis of restriction fragments of the two purified DNA samples gave distinct banding patterns that were characteristic of the two species of protozoan parasites.     

Molecular testing for Trichomonas vaginalis in women: results from a prospective U.S. clinical trial

Trichomoniasis is a common sexually transmitted disease associated with preterm birth, low birth weight, and increased susceptibility to infection with other pathogenic sexually transmitted microorganisms. Nucleic acid amplification tests for Trichomonas vaginalis have improved sensitivity for detecting infected individuals compared to existing culture-based methods. This prospective, multicenter U.S. clinical trial evaluated the performance of the automated Aptima T. vaginalis assay for detecting T. vaginalis in 1,025 asymptomatic and symptomatic women. Vaginal swab, endocervical swab, ThinPrep PreservCyt, and urine specimens were collected. Subject infection status was determined by wet-mount microscopy and culture. Aptima T. vaginalis assay performance was determined for each specimen type by comparison to subject infection status. Of 933 subjects analyzed, 59.9% were symptomatic. Aptima T. vaginalis clinical sensitivity and specificity were, respectively, 100% and 99.0% for vaginal swabs, 100% and 99.4% for endocervical swabs, 100% and 99.6% in ThinPrep samples, and 95.2% and 98.9% in urine specimens. Aptima T. vaginalis performance levels were similar in asymptomatic and symptomatic subjects. This study validates the clinical performance of the Aptima T. vaginalis assay for screening asymptomatic and symptomatic women for T. vaginalis infection.     

Ankylosing spondylitis associated with Trichomonas vaginalis infection.

A patient is described who developed signs and symptoms of ankylosing spondylitis after prostatitis due to Trichomonas vaginalis. Chronic prostatitis of unknown cause had previously been reported as being common in patients with ankylosing spondylitis. The observations in this case raise the possibility that T. vaginalis might play a role in the prostatitis and pathogenesis of ankylosing spondylitis in some patients.     

Characterization of Trichomonas vaginalis virus proteins in the pathogenic protozoan T. vaginalis

Summary.  The 4.6-kb double-stranded (ds) RNA of Trichomonas vaginalis virus (TVV)-T1 has been shown to encode two overlapping genes, cap and pol. In this study, a serum for specifically detecting viral cap gene product was raised against a recombinant protein, and sera for specifically detecting pol gene product were raised against synthetic oligopeptides. A 75-kDa major protein and a 160-kDa minor protein were detected by anti-CAP serum in a TVV-T1 sample, indicating that the 75-kDa protein is the viral capsid protein. The 160-kDa protein alone was also detected by two distinct anti-POL sera, indicating that the pol gene is expressed as a CAP-POL fusion protein. These results suggest that the TVV-T1 genome is arranged into a cap-pol organization in a manner similar to that of viruses in family Totiviridae. Accepted December 12, 1997 Received September 8, 1997     

Aminotransferase activities in Trichomonas vaginalis

A survey of aminotransferase activities present in a cell-free extract of the anaerobic protozoan, Trichomonas vaginalis was performed. 2-Oxoglutarate, oxaloacetate or phenylpyruvate acted as effective amino acceptors with tyrosine, phenylalanine, tryptophan, leucine, valine, isoleucine, aspartate, alanine, ornithine or lysine. Arginine, serine, glutamine, glycine, beta-alanine and gamma-aminobutyrate were not active as amino donors. With pyruvate as acceptor, significant, yet low, activity was seen only with glutamate, lysine or phenylalanine. Partial purification of enzymes catalysing transamination of leucine, valine, isoleucine, alanine, ornithine and lysine were carried out. A single enzyme catalysed the transamination of ornithine and lysine. The substrate specificity of this enzyme is novel. A separate enzyme catalysed the transamination of all three branched chain amino acids. A third enzyme catalysed the alanine aminotransferase reaction. A fourth enzyme catalysing the transamination both of aromatic amino acids and aspartate has previously been purified [Lowe, P.N. and Rowe, A.F. (1985) Biochem. J. 232, 689-695].     

Cell culture compared with broth for detection of Trichomonas vaginalis.

Trichomonas vaginalis can be grown in cell culture. We studied the growth kinetics of T. vaginalis in McCoy cell culture compared with that in a conventional broth medium (Diamond TYI-S-33 medium supplemented with 10% heat-inactivated bovine serum [TYI]). In the presence of McCoy cells and two parts cell culture medium to one part TYI, a peak concentration of 2 X 10(6) to 6 X 10(6) T. vaginalis per ml was consistently achieved with inocula as low as three T. vaginalis cells per ml. Without cells, this medium did not support growth of T. vaginalis. T. vaginalis in TYI in 1-ml vials with or without McCoy cells demonstrated poor growth. In tubes containing 10 ml of TYI, inocula grew to 2 X 10(6) to 6 X 10(6) T. vaginalis per ml, but at least 3 X 10(3) T. vaginalis per tube was required to initiate growth. Thus, in vitro, cell culture was more sensitive than TYI broth in detecting low numbers of T. vaginalis. In a subsequent clinical comparison of broth and cell culture for isolation of T. vaginalis from 188 vaginal specimens and 21 urethral specimens from men, the results were in agreement for 206 specimens (98.6%). There were no situations in which culture was negative and a saline preparation showed motile trichomonads. For women, using a positive culture as the indicator of true positivity, the sensitivity of detection of T. vaginalis was 83% with the Pappenheim stain and 77% with saline preparations. These studies show that cell culture can be used for isolation of T. vaginalis from clinical specimens; it gave results comparable to those of broth culture for the group of mainly symptomatic women. Further studies should be performed to determine its utility in clinical populations such as asymptomatic women and men with and without symptoms, in which T. vaginalis is more likely to be present in low numbers.     

Isolation of a cell-detaching factor of Trichomonas vaginalis.

The pathogenetic role of soluble products of Trichomonas vaginalis growth in culture is controversial. To evaluate this role, T. vaginalis was grown in broth and cell culture and the cell-free filtrate was applied to fresh cell culture monolayers. When adjusted to pH 6.5, filtrates obtained from 22-h culture growth totally disrupted McCoy, HEp-2, human foreskin fibroblast, and Chinese hamster ovary cell monolayers within 6 h. These detached cells remained greater than 90% viable. This cell-detaching factor (CDF) was heat and acid labile, with a pH optimum of 6.5. CDF has trypsinlike activity which disrupts monolayer cells, but cells do not die if the pH is controlled. CDF was purified by ethanol precipitation, ammonium sulfate fractionation, and ion-exchange and gel filtration column chromatography. A 200,000-molecular-weight glycoprotein which was also immunogenic by immunoblot with human sera reactive to T. vaginalis was isolated in this manner. This confirms the presence of a specific soluble CDF derived from T. vaginalis whose application may be important as a diagnostic tool and in further studies of pathogenesis.