An in vitro assay for drug sensitivity of Trypanosoma congolense using in vitro-derived metacyclic trypanosomes

Cross-resistance associated with development of resistance to isometamidium in a clone of Trypanosoma congolense

“…On the basis of CD 50 s in mice, the 94-fold increase in resistance was shown to be associated with a 3.4-fold increase in resistance to diminazene, a 33-fold increase in resistance to homidium, and a 4.2-fold increase in resistance to quinapyramine. Similar results were obtained with the parental clone, T. congolense IL 1180, and the most resistant derivative, T. congolense IL 3343, when their drug susceptibilities were characterized in vitro by using metacyclic trypanosomes (6). The high level of cross-resistance to homidium and the low level of cross-resistance to diminazene are consistent with the field observations of Stephen (19) and Whiteside (21) and confirm the rationale for using diminazene as a "sanative" combination with isometamidium in the field to abrogate the development of resistance to isometamidium (21).…”