Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2004
Publication Date: 5/24/2004
Citation: Gupta, G.D., Lakritz, J., Saville, W.J., Livingston, R.S., Dubey, J.P., Middleton, J.R., Marsh, A.E. 2004. Antigenic evaluation of a recombinant baculovirus-expressed Sarcocystis neurona SAGI antigen. Journal of Parasitology. 90:1027-1033. Interpretive Summary: Sarcocystis neurona is a single-celled parasite that causes a fatal illness in horses in North America. Diagnosis of illness due to this parasite during life is difficult. Scientists at the Beltsville Agricultural Research Center and The University of Missosuri describe modification of a serologic test for the diagnosis of S. neurona infection in horses. The results will be of interest to biologists, parasitologists and veterinarians.
Technical Abstract: Sarcocystis neurona is the primary parasite associated with equine protozoal myeloencephalitis (EPM). This is a commonly diagnosed neurological disorder in the Americas infecting the central nervous system of horses. Current serologic assays utilize culture-derived parasites as antigen. This requires large numbers of parasites to be grown in culture, which is very labor intensive and time consuming. Also, culture-derived whole parasite preparation contains conserved antigens that may cross-react with antibodies against other Sarcocystis species and members of Sarcocystidae such as Neospora spp., Hammondia spp., and Toxoplasma gondii. Therefore, there is a need to develop an improved method for the detection of S. neurona-specified antibodies. The sera of infected horses react strongly to surface antigen 1 (SnSAG1) - 29 kDa protein in immunoblot analysis suggesting that it is an immunodominant antigen. The SnSAG1 gene of S. neurona was cloned and recombinant S. neurona SAG1 protein (rSnSAG1-Bac) was expressed using a baculovirus system. By immunoblot analysis, the rSnSAG1-Bac antigen detected antibodies to S. neurona from naturally infected and experimentally inoculated equids, cats, rabbit, mice, and skunk. This is the first report of a baculovirus-expressed recombinant S. neurona antigen being used to detect anti-S. neurona antibodies in a variety of host species.