Differentiation of Sarcocystis neurona from eight related coccidia by random amplified polymorphic DNA assay

Four isolates of Sarcocystis neurona from horses with equine protozoal myeloencephalitis and eight species of coccidia from the genera Sarcocystis, Toxoplasma or Eimeria were differentiated using the random amplified polymorphic DNA assay. A single, common, 550-bp DNA fragment was amplified from the DNA of each S. neurona isolate using a 16-nucleotide primer. Crosshybridization analyses among S. neurona isolates showed that DNA fragments had at least partial sequence homology. The primer generated several DNA fragments, including a 550-bp DNA fragment, from S. cruzi, Eimeria falciformis, E. neischulzi, E. ahsata and E. bovis. DNA hybridization analyses indicated no sequence homology between these fragments and the 550-bp DNA fragment generated from S. neurona. The S. neurona 550-bp DNA fragment also did not hybridize with genomic blots of various other coccidia. These results suggest that the S. neurona DNA fragment may be exploited as a species-specific probe for this parasite.