Genetic markers for closely-related parasitic nematodes.

Seven species of closely-related nematode parasite (Trichostrongylus axei, T. colubriformis, T. probolurus, T. retortaeformis, T. rugatus, T. vitrinus and T. tenuis) were characterized using a polymerase chain reaction-linked restriction fragment length polymorphism technique (PCR-RFLP). The rDNA region spanning the first and second internal transcribed spacers as well as the 5.8S rDNA gene (ITS+) was amplified from isolates of each of the seven species, digested separately with six restriction endonucleases (Dra I, Hinf I, Rsa I, Vsp I, Nla III and Tsp 509 I) and the fragments separated by agarose gel electrophoresis. PCR-RFLP of ITS+ produced characteristic patterns for each Trichostrongylus species examined. No variation in RFLP patterns was observed among different isolates for species where multiple isolates were examined. The present study demonstrates that the ITS+ provides genetic markers for the species identification of closely-related parasitic nematodes, and indicates the usefulness of these markers for diagnostic purposes, and epidemiologic and molecular-systematic studies on parasites and other eukaryotic organisms.