DIFFERENCES IN A RIBOSOMAL DNA-SEQUENCE OF STRONGYLUS SPECIES ALLOWS IDENTIFICATION OF SINGLE EGGS

In the current study, molecular techniques were evaluated for the spec ies identification of individual strongyle eggs, Adult worms of Strong ylus edentatus, S. equinus and S. vulgaris were collected at necropsy from horses from Australia and the U.S.A, Genomic DNA was isolated and a ribosomal transcribed spacer (ITS-2) amplified and sequenced using polymerase chain reaction (PCR) techniques. The length of the ITS-2 se quence of S. edentatus, S. equinus and S. vulgaris ranged between 217 and 235 nucleotides. Extensive sequence analysis demonstrated a low de gree (0-0.9%) of intraspecific variation in the ITS-2 for the Strongyl us species examined, whereas the levels of interspecific differences ( 13-29%) were significantly greater, Interspecific differences in the I TS-2 sequences allowed unequivocal species identification of single wo rms and eggs using PCR-linked restriction fragment length polymorphism . These results demonstrate the potential of the ribosomal spacers as genetic markers for species identification of single strongyle eggs fr om horse faeces.