Experimentally induced intravaginal Tritrichomonas foetus infection in a mouse model

Abstract

The interest to develop research on the host-parasite relationship in bovine tritrichomonosis has accomplished the use of experimental models alternative to cattle. The BALB/c mouse became the most appropriate species susceptible to vaginal Tritrichomonas foetus infection requiring previous estrogenization. For the need of an experimental model without persistent estrogenization and with normal estrous cycles, the establishment and persistence of vaginal infection on BALB/c mouse with different concentrations of T. foetus in two experimental groups was evaluated. Group A was treated with 5mg of β-estradiol 3-benzoate to synchronize the estrous, 48 hours before the T. foetus vaginal inoculation, and Group B was inoculated in natural estrus. At 5-7 days after treatment, estrogenic effect decreased allowing all animals to cycle regularly during the experiment. From the first week post-infection, samples of vaginal mucus were taken from all animals during 34 weeks, in order to evaluate the course of infection and the stage of the estrus cycle. Group A showed 93.6% of infected animals, and Group B showed 38%. Different doses of T. foetus were assayed to establish the vaginal infection, with a persistence of 34 weeks. Although different behavior was observed in each subgroup belonging to either Group A or Group B, there were no significant differences among the infecting doses used. The b-estradiol 3-benzoate treatment had a favorable effect on the establishment of the infection (P<0.0001), but it did not influence its persistence (P=0.1097). According to the results, an experimental mouse model is presented, appropriate for further studies on mechanisms of pathogenicity, immune response, protective evaluation of immunogen and therapeutic effect of drugs.

Apoptosis and cell proliferation in the mouse model of embryonic death induced by Tritrichomonas foetus infection

“…Vaginal cytology was used to confirm the presence of T. foetus and to determine the oestrous cycle phase. The presence of mobile protozoa with typical T. foetus morphology in mucus samples of inoculated mice confirmed the infection (Soto et al, 2005).…”

“…In addition, it has been shown that mice treated with oestrogen were infected at a higher percentage than those untreated (St Claire et al, 1994). We have satisfactorily reproduced the disease using low-dose oestrogens to synchronise oestrus in nonpregnant BALB/c mice (Soto et al, 2005). Shortly later, we have reproduced bovine tritrichomonosis in pregnant BALB/c mice treated with a low dose of estrogens (Barbeito et al, 2008).…”

“…A pathogenic T. foetus strain isolated from bovine preputial washes (Soto et al, 2005) was cultured in trypticase-yeast-extract-maltose medium (TYM) (Diamond, 1987) and then the sample was centrifugated at 900 g three times with phosphate buffered solution (PBS, pH 7.2) for 10 min. Each member of the infected group was intravaginally inoculated with 10 μl of a suspension containing 9 × 10 7 T. foetus/ml, whereas the control group was intravaginally inoculated with PBS.…”

Lectin Binding Pattern in the Uterus of Pregnant Mice Infected with Tritrichomonas foetus

“…Laboratory animal models represent an excellent tool for unravelling the pathogenesis of the infection (St Claire et al, 1994;Hook et al, 1997). BALB/c mice are the most susceptible laboratory animal and the disease can be reproduced in this strain using low-dose oestrogen to synchronize oestrous (Soto et al, 2005). Genital tritrichomonosis has also been induced in pregnant BALB/c mice treated with a low dose of oestrogen (Agnew et al, 2008;Barbeito et al, 2008).…”

“…To confirm synchronization of oestrous, vaginal cytology was performed 24 and 48 h later. Two days after cycle synchronization the infected group (n ¼ 17) was inoculated intravaginally with 10 ml of a suspension containing 9 Â 10 7 T. foetus/ml (Soto et al, 2005), while the control group (n ¼ 14) was given phosphate buffered saline (PBS) by the same route. Twelve days later vaginal cytology was again analyzed in order to determine the phase of the oestrous cycle and to confirm the presence of T. foetus in the infected animals.…”