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Four genetic constructions have been designed, capable of producing in E. coli the hybrid beta-galactosidases containing the encephalitogenic determinant 114-122 of myelin basic protein. The ability of chromatography-purified proteins to cause allergic encephalomyelitis in guinea pigs has been investigated. Only one out of four proteins carrying at least one complete replica of encephalitogenic determinant did induce allergic encephalomyelitis in animals. Effects of the structural context of the encephalitogenic determinant on its functional activity are discussed.

Main encephalitogenic protein was isolated from bovine medulla spinalis and separated into homogenous polypeptide fractions by gel filtration; some of these fractions had the high encephalitogenic activity. The main protein and its fractions, possessing the encephalitogenic activity, caused a development of cross-reacting antibodies and a sensitization to intracutaneous administration of encephalitogenic preparations in animals. Non-encephalitogenic main protein sensitized animals only to this protein and did not induce the formation of distinct amount of antibodies. The amino acid composition of the encephalitogenic polypeptide is exhibited.

Encephalitogenic, immunogenic properties of the polypeptide fraction of myelin basic protein (FBP) and CNS lesions have been examined in animals with experimental allergic encephalomyelitis (EAE). FBP was isolated from bovine spinal cord using column chromatography. Administration of 1.0 or 0.1 microgram FBP mixed with complete Freund adjuvant caused neurological and histological EAE manifestations in 76% and 26% of guinea-pigs, respectively. Circulating anti-FBP antibodies were not found in sensitized animals, whereas the incidence and intensity of skin reaction of delayed type hypersensitivity to FBP correlated with the development of EAE and the onset of the disease. Perivascular cell infiltration and demyelination noted in the spinal cord and brain of guinea-pigs were similar to those observed after inoculation of the brain white matter or brain tissue homogenate.

Protein SCP is found in myelin of spinal cord and spinal roots. It is shown that its amount accounts for 12% of the total protein content in myelin of spinal roots and only for 2% in myelin of spinal cord. Almost all the studied protein is extracted from myelin with 0.1 M NaCl (80-90%). The absolute identity of protens SCP and P2 is established using the cross reaction immunodiffusion with monospecific antisera. It is shown that- N-terminal amino acid in protein SCP, like in protein P2 is blocked. On the basis of the data obtained a conclusion is made that protein P2 is not an integral protein of myelin. However, myelin is capable under conditions of a nonionic medium of binding protein which then may be easily extracted by increasing the medium ionic strength. This gave reasons to propose a method for protein P2 isolation from myelin using 0.15 M NaCl with the subsequent purification by means of Sephadex G-50 gelfiltration.

Basic protein (SCP) known as antiencephalytogenic was isolated from the bull spinal cord and spinal roots. The protein is purified to a molecular homogeneous state, some of its physicochemical properties are studied. Molecular homogeneity of the protein is established by the method of disk electrophoresis in 15% polyacrylamide gel with sodium dodecyl sulphate present and by analytic ultracentrifugation. During electrophoresis in 15% polyacrylamide gel at pH 4.0 the protein movement occurs only in one zone, and at pH 7.0 three closely located zones are formed. The protein molecular weight determined by different methods is about 13500. The protein amino acid composition is determined and it is shown that 9.6 mole of amide nitrogen falls on 1 mole of the protein. The presence of the tertiary structure in the protein is supposed.