Histological and lectin binding changes in the genital tract of mice infected with Tritrichomonas foetus.

An experimental murine model of bovine genital tritrichomonosis is described. Female mice were inoculated per vaginam with Tritrichomonas foetus and a sample of the study population was killed every 3 days up to 60 days post-infection. Microscopical changes in the reproductive organs were assessed and immunohistochemistry was used to detect T. foetus within these tissues. Lectin histochemistry was used to determine changes in the expression of carbohydrates within the reproductive mucosa. A range of microscopical changes were detected in the uterine endometrium by 10 days post-inoculation and these were associated with the presence of the protozoan. The endometrial changes included endometritis and ulceration, mucosal atrophy and glandular metaplasia, and were similar to those reported in naturally infected cows. Changes in lectin binding were recognized first in the vagina where there was increased binding of Ulex europaeus agglutinin-1 (UEA-1) which was maximal on day 16 post-inoculation. Within the uterus, there was increased binding of soy bean agglutinin (SBA) which was maximal on day 19 post-inoculation, and of peanut agglutinin (PNA) which was maximal on day 16 post-inoculation. These changes in carbohydrate expression parallel the infection kinetics, since they appeared first in the vagina and later in the uterus. The changes may reflect either a host reaction against the infection or the production of enzymes by T. foetus, which act to enhance adhesion and colonization of the genital organs by the organism. The kinetics and pathogenesis of this murine infection are similar to those of the natural bovine disease, suggesting that this model system may be valuable for further studies of this disease.