Sarcocystis neurona is the primary parasite associated with equine protozoal myeloencephalitis (EPM). This is a commonly diagnosed neurological disorder in the Americas that infects the central nervous system of horses. Current serologic assays utilize culture-derived parasites as antigen. This method requires large numbers of parasites to be grown in culture, which is labor intensive and time consuming. Also, a culture-derived whole-parasite preparation contains conserved antigens that could 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–specific antibodies. The sera of infected horses react strongly to surface antigen 1 (SnSAG1), an ∼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 with the use of 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.
ANTIGENIC EVALUATION OF A RECOMBINANT BACULOVIRUS-EXPRESSED SARCOCYSTIS NEURONA SAG1 ANTIGEN
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G. D. Gupta, J. Lakritz, W. J. Saville, R. S. Livingston, J. P. Dubey, J. R. Middleton, A. E. Marsh; ANTIGENIC EVALUATION OF A RECOMBINANT BACULOVIRUS-EXPRESSED SARCOCYSTIS NEURONA SAG1 ANTIGEN. J Parasitol 1 October 2004; 90 (5): 1027–1033. doi: https://doi.org/10.1645/0022-3395(2004)090[1027:AEOARB]2.0.CO;2
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