Increased pfmdr1 copy number and sequence polymorphisms in Plasmodium falciparum isolates from Sudanese malaria patients treated with artemether-lumefantrine

Abstract

Molecular markers for surveillance of Plasmodium falciparum resistance to current antimalarials are sorely needed. A 28-day efficacy study of artemether-lumefantrine in eastern Sudan identified 5 treatment failures among 100 evaluable patients; 9 further individuals were parasite positive by PCR during follow-up. Polymorphisms in pfatpase6 and pfmdr1 were evaluated by DNA sequencing. One individual carried parasites with a novel pfmdr1 polymorphism (F1044L). pfmdr1 gene amplification in parasites prior to treatment occurred in three individuals who had recurrent infection during follow-up.

Fig. 1.

Frequency distribution of pfmdr1 copy number estimates. Estimates of pfmdr1 locus copy numbers obtained from 55 pretreatment isolates with complete follow-up data are grouped in bins of 0.1 copy units. The values shown represent the means of at least two independent experiments; each DNA sample in each experiment was run in duplicate. Red data represent pretreatment parasite isolates from patients without subsequent recurrent parasitemia. Green data represent pretreatment parasite isolates from patients with later recurrent parasitemia by microscopy and/or PCR. Isolates with copy number estimates of 1.8 and above were considered true duplications.