Trypanosoma brucei evansi: dyskinetoplasia and loss of infectivity after long-term in vitro cultivation.

Bloodstream forms of a stock of Trypanosoma brucei evansi were propagated in vitro for more than 14 months. After that period, all organisms were dyskinetoplastic and had lost their infectivity for mice. An increase in diminazene aceturate resistance in vitro was observed whereas the susceptibility to isometamidium chloride, quinapyramine sulphate and suramin was unaltered. Trypanosomes derived from the long term culture had a surface coat.