Group B arbovirus structural and nonstructural antigens. II. Purification of Saint Louis encephalitis virus intracellular antigens.

Three serologically distinct antigens were identified in homogenates of Saint Louis encephalitis (SLE) virus-infected cells after Brij-58 solubilization and diethylaminoethyl (DEAE)-cellulose chromatography. These antigens were designated as antigen I, II, and III. Immunodiffusion analyses showed that all antigen peaks which eluted from the DEAE-cellulose column contained the intracellular major envelope protein, antigen I. This protein was the only viral antigen which eluted at 0.125 M KCl in DEAE-cellulose column peak C. Optical density peak D, which eluted at 0.2 M KCl, contained both antigens I and III. Antigen III was purified from this column fraction approximately 200-fold by organic solvent extraction and chromatography on hydroxylapatite and Sepharose 6B. Purified antigen III had a molecular weight of 80,000 to 85,000 and contained only one antigenic determinant as judged by immunodiffusion analysis.