Analysis of the dynamics of trypanosoma evansi strain accumulation during laboratory cultivation

Abstract

The aim of the study was to identify optimal conditions for the accumulation and maintenance of viability of the Trypanosoma evansi strain during laboratory cultivation. The study was conducted from January to June 2025 in the parasitology laboratory of the Limited Liability Company "Scientific-Production Enterprise "Antigen” using experimental infection of male mice followed by morphological, culturological, and serological analysis of the pathogen. The results demonstrated a clear dependence of infection course and morphological characteristics of the pathogen on the infection dose and cultivation conditions. At the minimum dose, parasitemia in mice reached approximately 4.8×10⁶ cells/ml, at the medium dose – 1.1×10⁷ cells/ml, and at the high dose – up to 1.3×10⁸ cells/ml, accompanied by intensified clinical signs. Morphometric analysis revealed a reduction in cell length from 24.6 μm at low load to 20.3 μm at maximum load, and of the flagellum from 8.2 to 6.1 μm, along with an increase in the proportion of degenerative forms and kinetoplast displacement. In in vitro culture, growth exhibited an S-shaped pattern: from 6.8×10⁶ cells/ml on day five to a peak of 1.3×10⁷ cells/ml on day nine, followed by a decline in viability to 60%. Protein analysis showed a concentration of 2.3 mg/ml with dominant antigenic fractions around 30 and 55 kDa, confirming the diagnostic value of the obtained material. The results confirmed dose-dependent changes in parasitemia, morphology, in vitro growth, and protein profile of Trypanosoma evansi, highlighting the diagnostic and applied significance of the study. The findings can be used by veterinary laboratories and research centres for the development of serological tests and the control of trypanosomosis in livestock and working animals.