Group B arbovirus structural and nonstructural antigens. 3. Serological specificity of solubilized intracellular viral proteins.

Solubilized nonstructural antigen III from Saint Louis encephalitis (SLE)-Japanese B encephalitis (JBE)-West Nile (WN) and dengue-2 arbovirus-infected pig kidney cells was purified by employing Brij-58 solubilization, organic solvent extraction, and column chromatography. Diethylaminoethyl-cellulose column peak C eluate contained only intracellular viral envelope protein designated antigen I. Antigen I of SLE virus absorbed homologous neutralizing antibody; however, the intracellular nonstructural protein designated antigen III did not. The antigenic relationships of solubilized antigens I and III prepared from SLE, JBE, and WN virus-infected cells were determined by complement-fixation (CF) and immunodiffusion analyses. Solubilized antigen I of each virus cross-reacted broadly with both homologous and heterologous antibody at high antigen concentrations in the CF test. Antigen III of each virus reacted with only homologous antibody by both CF and immunoprecipitation. This study demonstrates that during SLE, JBE, WN, and dengue-2 infections, virus-specific proteins containing both type-specific and group-reactive determinants are synthesized. Antigen III, a nonstructural protein, is serologically virus type specific and may be useful as a type-specific diagnostic reagent.