The Largest Rabies-specific Antigen in Extracts of Infected Suckling Mouse Brains

Abstract

SUMMARYExtracts of rabies-infected suckling mouse brains purified by precipitation at pH 4"5, freed from smaller antigens by sedimentation at 161, I8og and digested with RNase, DNase and trypsin show in the ultracentrifuge a component of $20 ~ I6 to I8 which is lacking in extracts of normal suckling mouse brains similarly treated. The largest rabies soluble antigen ('outer antigen': Mead, I962b) has a sedimentation constant S~0 ~ I6 estimated by the 'biological' method of Poison & van Regenmortel 0960. The purified antigen appears to consist of rings or possibly single-turn helices about lOO in diameter containing about 0"57/zg. pentose (as ribose) per/zg, total nitrogen. The antigen also appears to contain deoxypentose. It is resistant to pancreatic RNase, DNase, trypsin and chymotrypsin, has a density of about 1.34 g./cma. in CsC1 and an electrophoretic mobility about 7/8 that of rabbit serum albumin at pH 8"5.Preparative density-gradient centrifugation in the analytical rotor of the Model E Spinco centrifuge is described. This allows the method to be applied to smaller particles than can be treated in the S.W. 39 rotor.