Characterization of a Sarcocystis neurona isolate from a Missouri horse with equine protozoal myeloencephalitis

Little information is available about antigenic Variation of Sarcocystis ne urona isolated from horses with equine protozoal myeloencephalitis, nor is there much information available on the specific antibody pattern to S. neu rona antigens of horses from different geographic regions where S. neurona isolates have been obtained. This communication reports on the characteriza tion of a new S. neurona isolate, SN-MU1, The isolate was obtained from a 3 -year old Thoroughbred that had asymmetrical neurological signs and localiz ed skeletal muscle atrophy. This S. neurona isolate is similar to other S, neurona isolates by molecular analysis of the internal transcribed spacer ( ITS-1) region and a random-amplified polymorphic DNA marker, but is phenoty pically distinct from the other S, neurona isolates examined. Evaluation of the antibodies from the affected horse and immunohistochemical results sug gested that antigenic variation of S. neurona can result in variable antibo dy-antigen reactivity observed in the S. neurona immunoblot test. (C) 2001 Elsevier Science B.V. All rights reserved.