Group B arbovirus structural and nonstructural antigens. I. Serological identification of Saint Louis encephalitis virus soluble antigens.

Saint Louis encephalitis virus-infected cells were solubilized with Brij-58 nonionic detergent, and the clarified supernatant fluid was analyzed by diethyl-aminoethyl-cellulose chromatography. Three serologically distinguishable antigens were identified in viral protein peaks which eluted from diethylaminoethyl-cellulose at 0.05, 0.075, 0.125 and 0.2 m KCl. Antigen I was found in all column peaks, whereas antigen II was found only in the 0.05 m KCl eluate and antigen III was found only in the 0.2 m eluate. Immunodiffusion studies revealed that antigens I and II share at least one antigenic determinant and that antigen III is immunologically distinct from either antigen I or II. Polyacrylamide gel electrophoresis of (3)H-leucine-labeled concentrated column peaks revealed that antigens I and II contain the major viral structural envelope and core proteins, respectively. Antigen III contains the largest virus-induced nonstructural polypeptide observed by polyacrylamide gel electrophoresis of (3)H-leucine-labeled Saint Louis encephalitis virus-infected cells.