Transcripts of the multidrug resistance genes in chloroquine-sensitive and chloroquine-resistantPlasmodium falciparum

Abstract

SUMMARYHomologues of the mammalian multidrug resistance gene have been identified in isolates and clones ofPlasmodium falciparumand designatedpfmdr1andpfmdr2.Mutations inpfmdr1have been associated with chloroquine resistance but confirmation could not be obtained in a genetic cross. We have examined the copy number and expression ofpfmdr1andpfmdr2in chloroquine-sensitive and -resistantP. falciparumand have found no relationship between the copy number of either gene and chloroquine resistance. However, a marked correlation was seen between levels of mRNA transcribed for each gene and chloroquine resistance. Two transcripts ofpfmdr1were detected, and in the asexual blood cycle an 8 kb transcript appeared first, followed by the appearance of a 7 kb species.