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Trichomonas vaginalis: strain differences in adhesion to plastic and virulence in vitro and in vivo
1Department of Human Microbiology, Sackler Faculty of Medicine, Tel Aviv University, Israel.
Abstract:
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.
Insights
Trichomonas vaginalis virulence in mice depends on the specific strain, not just its ability to adhere to serum components in culture. Strain-dependent factors, not just adhesion, determine the pathogenicity of this parasite.
Area of Science:
- Microbiology
- Parasitology
- Infectious Diseases
Background:
- Trichomonas vaginalis is a flagellated protozoan parasite causing trichomoniasis.
- Axenic culture of T. vaginalis allows for controlled study of parasite characteristics.
- Strain variation in virulence and adhesion is observed in clinical isolates.
Purpose of the Study:
- To investigate the relationship between adhesion properties and virulence of Trichomonas vaginalis strains in vitro and in vivo.
- To determine if adhesion to serum components correlates with the pathogenic potential of T. vaginalis.
- To assess the impact of axenic cultivation time on parasite virulence and adhesion.
Main Methods:
- Axenic cultivation of T. vaginalis strains in TYI-S-33 medium.
- Assessment of parasite adhesion in media containing bovine serum or Cohn fractions.
- In vitro cytotoxicity assays using HeLa cells.
- In vivo infectivity trials in mice.
Main Results:
- Adhesion characteristics varied among T. vaginalis strains and were not related to time in axenic culture.
- All tested strains showed similar in vitro cytotoxicity against HeLa cells.
- One high-adhesion strain was most virulent in mice, while a low-adhesion strain failed to infect.
- Extended axenic cultivation led to reduced virulence in some strains.
Conclusions:
- The in vivo pathogenic potential of T. vaginalis is inherently strain-dependent.
- Adhesion in serum-containing medium can differentiate strains but doesn't reliably correlate with virulence.
- Identifying serum adhesion factors is crucial to understand the link between T. vaginalis adhesion and pathogenicity.