Characterization of a highly repeated interspersed DNA sequence of Trypanosoma cruzi: its potential use in diagnosis and strain classification.

In the present paper we report the characterization of a repetitive DNA sequence from the genome of the Maracay strain of Trypanosoma cruzi. The sequence is 1025 nucleotides long and represent about 7% of the total nuclear DNA of the parasite with a copy number of 1-2 x 10(4) copies per genome. It is also present in a high copy number in several strains of T. cruzi but absent from other trypanosomatids and from the human genome. The DNA sequence is interspersed and present on many chromosomes. We show that the different copies of this repeat present extensive endonuclease restriction polymorphisms. Using 2 conserved oligonucleotide primers derived from the repetitive sequence, together with the polymerase chain reaction technique, the presence of less than 1/30 of a single parasite can be readily detected by ethidium bromide staining.