Neuritogenic Peptides Derived from Equine Myelin P2 Basic Protein Detect Circulating Antibodies in Ataxic Horses

Polyneuritis equi is an immune-mediated neurodegenerative condition in horses that is related to circulating demyelinating antibodies against equine myelin basic protein 2 (MP2). The present study examined the presence of circulating demyelinating antibodies against neuritogenic peptides of MP2 in sera from horses suspected of equine protozoal encephalomyelitis (EPM), a neurodegenerative condition in horses that may be immune-mediated. The goals of this study were to develop serum ELISA tests that may identify neuroinflammatory conditions in horses with EPM and indirectly relate the pathogenesis of inflammation to IL6 by serum C-reactive protein (CRP) concentration. Circulating antibodies against MPP, recombinant equine myelin P2 protein (rMP2), and CRP were assayed in 52 neurologically abnormal horses by ELISA in this retrospective study. We detected antibodies against MPP (40%), rMP2 (33%), and CRP (65%) in these horses that had a presumptive diagnosis of EPM. No cross-reactivity between the antigens was observed. An evaluation of the agreement between the assays (McNemar’s test) suggests as CRP values increase, the likelihood of a positive MPP ELISA also increases. Clinical signs of EPM may be due to an immune-mediated polyneuropathy that involves complex in vivo interactions with the IL6 pathway because MPP antibodies and elevated CRP concentrations were detected in some horses with S. neurona