Plasmodium falciparum: characterization of a 0.7-kbp, moderately repetitive sequence

A 692-bp-long repetitive sequence of Plasmodium falciparum was cloned. Two contiguous repeats were sequenced. The homology between them was 85%, the differences being due only to base replacements. The sequence was found 60 times repeated in the genome and was detected in 11 of 14 chromosomes. When used as a probe, the cloned fragment detected the parasite with the same sensitivity the 21-bp repeat (pRepHind) did. PCR amplification detected 0.02 pg of DNA, equivalent to a single parasite, in strains from America, Asia, and Africa. The restriction patterns were polymorphic and different among the strains. Analysis of lambda EMBL clones that contain the repetitive sequence confirms that it is present in various genomic contexts and is located subtelomerically.