{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,19]],"date-time":"2026-09-19T22:12:18Z","timestamp":1789855938000,"version":"4.0.1"},"reference-count":37,"publisher":"Cambridge University Press (CUP)","issue":"1","license":[{"start":{"date-parts":[[2009,4,6]],"date-time":"2009-04-06T00:00:00Z","timestamp":1238976000000},"content-version":"unspecified","delay-in-days":6639,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Parasitology"],"published-print":{"date-parts":[[1991,2]]},"abstract":"<jats:title>SUMMARY<\/jats:title><jats:p>Nine clones were derived from a drug-resistant<jats:italic>Trypanosoma congolense<\/jats:italic>stock (IL 2856) and characterized in mice for their sensitivity to isometamidium chloride and diminazene aceturate. All clones were derived from the stock without drug selection and expressed high levels of resistance to isometamidium chloride (50% curative dose [CD<jats:sub>50<\/jats:sub>] values ranging from 1\u00b75 to 5\u00b71 mg\/kg) and intermediate to high levels of resistance to diminazene aceturate (CD<jats:sub>50<\/jats:sub>values ranging from 5\u00b71 to 21\u00b70 mg\/kg). By contrast, the isometamidium chloride and diminazene aceturate CD<jats:sub>50<\/jats:sub>values for a drug-sensitive clone,<jats:italic>T. congolense<\/jats:italic>IL 1180, were 0\u00b7018 mg\/kg and 2\u00b73 mg\/kg, respectively. For both drugs, there appeared to be significantly different levels in expression of drug resistance amongst the 9 clones derived from IL 2856. Isoenzyme analysis of 7 enzymes showed that all 9 clones expressed the same electrophoretic variants. Thus, all 9 clones were identical for these phenotypic markers. The clone which expressed the highest level of resistance to isometamidium in mice (IL 3270) was transmitted to Boran cattle via the bite of infected<jats:italic>Glossina morsitans centralis<\/jats:italic>. IL 3270 produced an infection rate in tsetse of 5\u00b70%. The resulting infections in cattle were shown to be resistant to intramuscular treatment with 2\u00b70 mg\/kg isometamidium chloride and 14\u00b70 mg\/kg diminazene aceturate. This contrasts with doses of 0\u00b725 mg\/kg isometamidium chloride or 3\u00b75 mg\/kg diminazene aceturate which are deemed sufficient to cure fully sensitive infections. Finally, 9 clones (subclones) were derived from IL 3270 and characterized in mice for their sensitivity to isometamidium chloride. Seven of the subclones expressed a significantly lower level of resistance to isometamidium than the parental clone and amongst the subclones there was significant variation in resistance. Thus, expression of a high level of resistance to isometamidium appears to be unstable in the rodent host and at least a component of the genetic determinant(s) for this drug-resistant phenotype is (are) likely to be unstable.<\/jats:p>","DOI":"10.1017\/s0031182000060388","type":"journal-article","created":{"date-parts":[[2009,6,5]],"date-time":"2009-06-05T14:34:52Z","timestamp":1244212492000},"page":"93-100","source":"Crossref","is-referenced-by-count":32,"title":["Variation in resistance to isometamidium chloride and diminazene aceturate by clones derived from a stock of<i>Trypanosoma congolense<\/i>"],"prefix":"10.1017","volume":"102","author":[{"given":"A. S.","family":"Peregrine","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G.","family":"Knowles","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. 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