A comparison of five methods for DNA isolation from liver and rumen flukes to perform ITS-2+ amplification.

Five different DNA isolation methods (4 commercial kits and a modification of phenol-chloroform method) were compared for the discrimination of adults of Fasciola hepatica and Dicrocoelium dendriticum (liver flukes), and Calicophoron daubneyi (rumen fluke) collected from sheep in southern Italy. The second internal transcribed spacer (ITS-2) of ribosomal DNA (rDNA) plus flanking 5.8S and 28S sequence (ITS-2+) was amplified by polymerase chain reaction (PCR) from serial diluted DNA templates (6 ng - 60 fg) of each fluke species. Overall, in terms of efficiency in detection limit, the best results were obtained either with phenol-chloroform purification or with QIAamp DNA Mini Kit (Qiagen), but using this latter method, rapid, safe and not expensive, an increased level of sensitivity sufficient to detect small amounts of target-DNA was achieved. In addition, electrophoresis analysis following PCR also showed that ITS-2+ could be useful as a genetic marker for the molecular identification of F. hepatica, D. dendriticum and C. daubneyi in definitive and intermediate hosts. Furthermore, for the first time, the ITS-2 sequence of D. dendriticum was defined.