A RAPD-PCR DERIVED MARKER CAN DIFFERENTIATE BETWEEN PATHOGENIC AND NONPATHOGENIC SARCOCYSTIS SPECIES OF SHEEP

Random amplified polymorphic DNA (RAPD)-PCR was used to differentiate among four cyst-forming coccidia of sheep, Sarcocystis tenella, Sarcoc ystis gigantea, Sarcocystis arieticanis, and Toxoplasma gondii. Genomi c DNA of the four parasite species was amplified using RAPD-PCR and th e DNA fragments were separated on agarose gels. A RAPD-PCR band derive d from S. tenella was isolated from the gel and subcloned into pUC18. The insert was sequenced and found to be 1278 nucleotides long. This s equence appeared to be cryptic in nature as it showed no significant s equence peculiarities or similarity with any other known sequences eit her at the nucleotide or derived amino acid levels. The recombinant pl asmid was radiolabelled and used as a probe in Southern hybridization. This probe, termed pSTF10, hybridised to Mbo 1 restricted genomic DNA of S. tenella and S. arieticanis, bur not to DNA of S. gigantea, T. g ondii, mouse, or sheep. It is likely that STF10 will become a valuable diagnostic tool for Sarcocystis infections in sheep to differentiate between pathogenic species of this genus and S. gigantea or T. gondii. (C) 1996 Academic Press Limited