To understand the mechanism of Multiple Sclerosis (MS), an autoimmune demyelinating disease, the researchers developed an experimental animal model for MS, which is called EAE (Experimental Allergic Encephalomyelitis). There are several methods for inducing this animal model. In this research the active EAE, which is developed by injecting bovine myelin antigens into genetically susceptible animals, was used. Proteolipid protein (PLP), which is a prominent neuroantigen, was extracted from fresh bovine brain, and used for inducing EAE in female Balb/C and Guinea pig. Animals were weighed and examined daily for clinical symptoms. Also histological sections from EAE brains were prepared. These sections showed infiltration, congestion and demyelination.