Characterization of four species of Trichuris (Nematoda : Enoplida) by their second internal transcribed spacer ribosomal DNA sequence

Adult worms of Trichuris ovis and T. globulosa were collected from Ovis ari es (sheep) and Capra hircus (goats). T. suis was isolated from Sus scrofa d omestica (swine) and T. leporis was isolated from Lepus europaeus (rabbits) in Spain. Genomic DNA was isolated and a ribosomal internal transcribed sp acer (ITS2) was amplified and sequenced using polymerase-chain-reaction (PC R) techniques. The ITS2 of T. ovis and T. globulosa was 407 nucleotides in length and had a GC content of about 62%. Furthermore, the ITS2 of T. suis and T. leporis was 534 and 418 nucleotides in length and had a GC content o f about 64.8% and 62.4%, respectively. There was evidence of slight variati on in the sequence within individuals of all species analyzed, indicating i ntraindividual variation in the sequence of different copies of the ribosom al DNA. Furthermore, low-level intraspecific variation was detected. Sequen ce analyses of ITS2 products of T. ovis and T. globulosa demonstrated no se quence difference between them. Nevertheless, differences were detected bet ween the ITS2 sequences of T. suis, T. leporis, and T. ovis, indicating tha t Trichuris species can reliably be differentiated by their ITS2 sequences and PCR-linked restriction-fragment-length polymorphism (RFLP).