Multiple DNA markers differentiate Sarcocystis neurona and Sarcocystis falcatula

Studies designed to investigate the causative agent of equine protozoal mye loencephalitis and its life cycle have been hampered by the marked similari ty of Sarcocystis neurona to other Sarcocystis spp. present in the same def initive host. Random-amplified polymorphic DNA techniques were used to ampl ify DNA from isolates of S. neurona and Sarcocystis falcatula. DNA sequence analysis of polymerase chain reaction (PCR) products was then used to desi gn PCR primers to amplify specific Sarcocystis spp. DNA products. The ribos omal RNA internal transcribed spacer was also amplified and compared betwee n S. neurona and S. falcatula. Useful sequence heterogeneity between the 2 organisms was identified, creating potential markers to distinguish these S arcocystis spp. These markers were used to characterize Sarcocystis isolate s from opossum (Didelphis virginiana) feces. Our data suggest that S. neuro na and S. falcatula can be differentiated with these markers and that multi ple Sarcocystis spp., including S. neurona and S. falcatula, are shed by op ossums.