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Tritrichomonas foetus: comparison of isolate virulence in an estrogenized mouse model
R R Hook1, M C St Claire, L K Riley
1Department of Veterinary Pathology, College of Veterinary Medicine, University of Missouri, Columbia 65211, USA.
Abstract:
Previous studies indicated that Tritrichomonas foetus isolate ATCC 30003 was capable of maintaining only short-term genital infection in estrogenized BALB/c mice. In the present study, the ability of eight T. foetus isolates to establish and maintain infections in intravaginally inoculated estrogenized BALB/c mice was examined. All isolates were found to be equally capable of establishing genital infections but varied greatly in ability to maintain infections. One isolate maintained infection for less than 7 weeks, four isolates maintained intermediate infections lasting less than 13 weeks, and three isolates maintained chronic infections of greater than 26 weeks. Varying the number of trophozoites inoculated intravaginally decreased the ability of isolates to establish infection but did not affect maintenance of infection. Prolonged passage of T. foetus isolates either in vivo in an estrogenized nu/nu BALB/c mouse or by in vitro culture failed to affect their ability to maintain infection, suggesting that virulence was parasite-dependent and not related to environment-induced changes. Co-infection of estrogenized mice with isolates ATCC 30003 and MU Y32 failed to increase the length of ATCC 30003 infections or decrease the length of isolate MU Y32 infections. Taken together these results indicate that T. foetus isolates vary greatly in virulence in estrogenized BALB/c mice and provide evidence suggesting that maintenance of infection is a parasite-controlled factor.
Insights
Tritrichomonas foetus isolates show varying virulence in mice, with some causing chronic infections. This parasite-controlled factor, not environmental changes, determines infection maintenance.
Area of Science:
- Veterinary Parasitology
- Infectious Diseases
- Host-Parasite Interactions
Background:
- Previous research showed Tritrichomonas foetus ATCC 30003 caused only short-term genital infections in estrogenized mice.
- The variability in virulence among T. foetus isolates is not well understood.
Purpose of the Study:
- To investigate the ability of eight T. foetus isolates to establish and maintain genital infections in estrogenized BALB/c mice.
- To determine if infection maintenance is influenced by parasite-dependent or environmental factors.
Main Methods:
- Eight Tritrichomonas foetus isolates were inoculated intravaginally into estrogenized BALB/c mice.
- Infection establishment and duration were monitored.
- T. foetus isolates underwent in vivo and in vitro passage to assess environmental influences.
- Co-infection experiments were conducted.
Main Results:
- All eight T. foetus isolates established genital infections equally.
- Isolates varied significantly in infection maintenance: one (<7 weeks), four (intermediate, <13 weeks), and three (chronic, >26 weeks).
- Inoculum size affected infection establishment but not maintenance.
- In vivo and in vitro passage did not alter infection maintenance capabilities.
- Co-infection did not alter the duration of infections caused by individual isolates.
Conclusions:
- Tritrichomonas foetus isolates exhibit significant variation in virulence in estrogenized BALB/c mice.
- The maintenance of genital infection is primarily a parasite-controlled factor, independent of environmental modifications.
- These findings highlight isolate-specific virulence as a key determinant in T. foetus pathogenesis.