Distinguishing Oesophagostomum dentatum from Oesophagostomum quadrispinulatum developmental stages by a single-strand conformation polymorphism method

At some life-cycle stages, it is impossible to distinguish between the two species of porcine nodular worm, Oesophagostomum dentatum and Oesophagostom um quadrispinlatum, using morphological features. A PCR-based single-strand conformation polymorphism technique was established to overcome this limit ation. The rDNA region spanning the second internal transcribed spacer was amplified by PCR from genomic DNA from morphologically well-defined adult w orms. The PCR products were then denatured and subjected to electrophoresis in a non-denaturing gel matrix. Single-strand conformation polymorphism an alysis of the products generated characteristic and reproducible patterns f or each of the two species and allowed their unequivocal delineation. The s ingle-strand conformation polymorphism was also applied effectively to asse ss the purity of nine laboratory-maintained cultures of infective third-sta ge larvae believed to be monospecific for O. dentatum or O. quadrispinulatu m. The analysis showed that all six O. dentatum cultures were indeed monosp ecific, whereas the three cultures believed to be monospecific for O. quadr ispinulatum were either a mixture of O. dentatum and O. quadrispinulatum la rvae or pure O. dentatum larvae. These findings demonstrated the usefulness of the single-strand conformation polymorphism approach for the routine mo nitoring of the purity of parasite "lines" and indicated Its value for stud ies on the population biology of porcine nodular worms. (C) 1998 Australian Society for Parasitology. Published by Elsevier Science Ltd. All rights re served.