A new repetitive DNA sequence from Trypanosoma cruzi

Tandemly repeated DNA sequences are found in the genome of higher eukaryotes, and have also been demonstrated in Trypanosoma cruzi. Repeated DNA sequences are potentially useful for the diagnostic detection of T. cruzi (A. Gonzales et al., 1984, Proc. Natl. Acad. Sci. USA, 81: 3356-3360). We have isoleted two clones from a genomic library of T. cruzi (Y strain) that contain, in one clone a family of at least seven copies of a repetitive sequence of approximately 600 base pairs, and in the other an independent copy of the same sequence. One copy of the repetition (HSP) and the independent clone (HCR) were sequenced by the Sanger procedure (Fig.). This sequence hybridized to four strains of T. cruzi tested and did not hybridize to eleven species of trypanosotids from five different Genera, being a good candidate for diagnostic assays. GenBank accession numbers: HSP#m31919, HCR#31920.

Detection of cytomegalovirus in urine of HIV-infected patients by DNA-DNA hybridization comparison with virus isolation, immunofluorescence and immunoperoxidase

Immunofluorescence and immunoperoxidase test directed against early viral antigens, and DNA-DNA hybridization were compared with viral isolation for their abilities to detect Cytomegalovirus (CVM) in the urine of 89 HIV infected patients. From the 100 urine samples collected, 70 were found positive by at least one method. Considering viral isolation as the "gold standard" technique, immunofluorescence and immunoperoxidase had a sensitivity of 92.3% and88% respectively, with a specificity in both cases of 95%. DNA-DNA hybridization showed a sensitivity of 90% but with lower (60%) specificity. All of the three assays were effective in detecting CVM from urine and the technical advantage of each is discussed.