Isolation and purification of a polymeric form of the glycoprotein of rabies virus.

Of the three major proteins associated with the rabies virus membrane, only the glycoprotein was found to be located on the external surface of the virus membrane. Glycoprotein prepared by treatment of rabies virus with Triton X-100 and purified by isoelectric focusing was found to be homogeneous with respect to size and isoelectric point. This material, which is free of phospholipids, is able to protect in vaccination experiments against a lethal challenge infection with rabies virus. The apparent mol. wt. of this component isolated under non-denaturing conditions is approx. 400000. The same material analysed by SDS polyacrylamide gel electrophoresis (PAGE) was found to consist solely of polypeptide chains of the G protein (mol. wt. 80000). A minor glycoprotein (gp 50), detected by PAGE of the Triton X-100 released material, appeared to be a breakdown product of the G-protein. Therefore the detergent released material represents homopolymers of the G-protein. Whether the antigenic determinants reside on the monomeric subunit or are a property of the polymeric form of the G-protein is discussed.