Appearance of virus-like particles in Tritrichomonas foetus after drug treatment.

Tritrichomonas foetus is a parasitic protist that infects the urogenital tract of cattle causing bovine trichomonosis. Virus-like particles (VLPs) in protozoa have been reported in several parasites including Trichomonas vaginalis, a human flagellate, but viruses were never described in T. foetus so far. Herein we show for the first time the presence of VLPs in T. foetus after several drug treatments. They were detected by electron microscopy and were confirmed by immunofluorescence microscopy using antibodies anti-virus proteins. These VLPs were always observed in clusters of variable size. Their preferential locations were at the cell periphery, close to the axostyle, and interestingly in some cases, inside the nucleus. Their appearance occurred when the parasites were under drug-treatments, such as cytoskeleton-affecting drugs (colchicine, vinblastine, taxol, nocodazole, and griseofulvin) or drugs inducing cell death, such as lactacystin and H(2)O(2). We propose that cytoskeleton participates in trichomonads of the process of virus release or maturation. These virus particles were not described previously probably because they were either in low amount or in a latent state.