Trichomoniasis: Genotype and Phenotype Correlations in African American Women
Condition: Trichomonas Infections
MeSH terms: Trichomonas Infections
Study type: Observational

Summary: 
      The hypothesis to be tested in this trial is that the different epidemiologic (including
      racial differences) and phenotypic manifestations exhibited by Trichomonas clinical isolates
      during infection are correlated with their genotypic strain classification. Two specific aims
      are proposed to test that hypothesis. Specific aim 1. Assess the significance of genotypic or
      phenotypic differences in the Trichomonas strains among African American women by HIV status.
      Specific aim 2. Determine the significance of genotypic or phenotypic differences in the
      Trichomonas strains circulating among women from two different racial groups, African
      American women and Caucasian women. The overall goals of these specific aims are to identify
      racial differences in the genotypic and phenotypic characteristics of Trichomonas strains,
      and to develop the ability to identify and classify Trichomonas infections in order to
      prioritize treatment and epidemiologic follow-up of individuals infected with isolates
      associated with adverse clinical outcomes (HIV transmission or acquisition, pregnancy
      complications, virulence, or drug resistance).
    

Detailed description: 
      Despite serious public health consequences, its widespread prevalence, rising drug resistance
      and treatment failures, little has been done to study the role of T. vaginalis genotype in
      transmission, virulence, occurrence of mixed infections, and the spread of drug resistance,
      primarily due to the lack of suitable assays for rapid strain typing. Previously utilized
      genotyping techniques for Trichomonas are inadequate due to problems with speed of analysis,
      sensitivity, and reproducibility between different labs. Multilocus sequence typing (MLST)
      combines speed, sensitivity, portability, accuracy, and reliability by determining nucleotide
      sequence polymorphisms (SNPs) present in small DNA fragments (300-400 nt) that are amplified
      by polymerase chain reaction (PCR) from a number (usually 6-7) of neutrally selected
      housekeeping genes. MLST assigns an allele fragment number (AFN) for each unique SNP or
      combination of SNPs present in a gene fragment and uses these to identify unique sequence
      types (STs) based on the AFN combinations in the collection of all the genes analyzed. MLST
      has been used extensively to study epidemiology, population structure, virulence and
      evolution in pathogenic bacteria but only for fungi among eukaryotes, due to the difficulty
      of interpreting MLST data in diploid organisms. However, T. vaginalis differs from other
      eukaryotes, possessing a stable haploid set of six chromosomes, and the investigators have
      developed an MLST genotyping system for T. vaginalis clinical isolates. The data (AFNs and
      STs) generated for each T. vaginalis strain by the MLST scheme we develop will be deposited
      in a freely accessible internet database. This MLST scheme will then be used to examine the
      relationships between strain genotypes and the clinical, epidemiologic, and physiologic
      manifestations of trichomoniasis.

      Trichomoniasis is characterized by a wide spectrum of clinical presentation and disease
      sequelae. This clinical variability is accompanied by a high degree of genetic diversity in
      Trichomonas vaginalis clinical isolates as we originally demonstrated and others have
      confirmed. The investigators hypothesize that correlations between genotype and clinical
      presentation are true for trichomoniasis and that T. vaginalis isolates differ in their
      capacity for clinical disease, severity, drug resistance, and disease sequelae. In support,
      several studies (10-40 patients) show a statistically significant correlation between the
      genetic relatedness of T. vaginalis isolates, using a random amplified polymorphic DNA (RAPD)
      technique, with their clinical presentation. Correlations between disease severity in
      trichomoniasis and in vitro phenotypic properties such as cytoadherence, cytotoxicity and
      expression of cysteine proteinase 30 kilo-dalton (kDa) protein have also been reported.
      Significant differences in cytoadherence to cell monolayers, differential protein expression,
      phagocytosis of target cells, ability to exert cytotoxic damage on cultured cells, and
      pathogenicity and mortality in mice have been demonstrated in T. vaginalis clinical isolates,
      indicating the wide variation in virulence properties present in Trichomonas isolates. The
      investigators have also demonstrated up to four-fold differences in secreted cysteine
      protease activity between cultured T. vaginalis clinical isolates. The accumulated evidence
      strongly supports a correlation between individual T. vaginalis strains and their capacity
      for virulence.

      For this specific study, at the initial enrollment/diagnosis visit the investigators will
      collect T. vaginalis isolates accompanied by a detailed clinical assessment, epidemiological
      information, and the results of in vitro testing of drug .resistance. This information will
      allow the investigators to determine if particular strains or groups of strains (as
      determined by MLST genotyping) are associated with asymptomatic infection, clinical severity,
      patient race, treatment failures, drug resistance, mixed infections or sexual history using
      univariate and multivariate analysis. This is significant because positive associations of
      particular strains or groups of strains with these factors, as the investigators expect to
      find, will necessitate changes in the way trichomoniasis is managed and treated with
      reference to the strains identified. The investigators will also independently test these
      variables for correlations with each other to identify variables or combinations of variables
      which may be associated with clinical manifestations of trichomoniasis.

      The information the investigators gather will also permit a better understanding of
      trichomoniasis in many additional ways. The investigators will culture T. vaginalis at test
      of cure (TOC) follow-up visits to genotype and determine their drug resistance in order to
      distinguish potential treatment failures or conversion to drug resistance (same genotype as
      original visit) from re-infection by another contact (different genotype). This is
      particularly significant for HIV+ women as their Trichomonas vaginalis infections are more
      difficult to cure and T. vaginalis may persist, undetectable by culture, only to re-emerge up
      to six months later. Trichomonas vaginalis is detected at TOC visits at much higher rates (up
      to 36 %) in HIV+ women than in HIV- women (8%) with most of these infections ascribed to
      treatment failures. Recent reports describe persistent, undetected T. vaginalis infections
      cultured 3 and 6 months after an initial negative TOC result in women who report no
      intervening sexual contacts. This is significant as a correlation of strain genotype with
      persistent infection will identify HIV+ individuals needing multiple TOC visits, use of more
      sensitive diagnostic tests, and perhaps longer treatment courses.
    

Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Patients presenting to clinic sites with symptoms of a sexually transmitted disease
      
Biospecimen description: 
      Trichomonas vaginalis clinical isolates
    
Keywords: Trichomonas vaginalis; trichomoniasis; MLST; Multilocus sequence typing