Partial Purification and Characterization of a Dengue Virus Soluble Complement-Fixing Antigen

Abstract

Rate-zonal centrifugation of dengue-2 infected mouse brain or cell culture has revealed two hemagglutinins (HA) and a non-hemagglutinating soluble complement-fixing (CF) antigen (1, 2). A rapidly sedimenting HA (RHA) consists of infectious particles measuring 48 to 50 nm in diameter and a slowly sedimenting HA (SHA) contains small doughnut structures measuring 14 nm in diameter. The third antigen was described as a soluble CF antigen (SCF) since it could not be readily removed from suspension by ultracentrifugation. Subsequent studies suggested that SCF is a nonstructural antigen which can be distinguished from the structural polypeptides of the virion by coelectrophoresis in polyacrylamide gels (R. D. Cardiff, W. E. Brandt, T. G. McCloud and P. K. Russell, to be published). SCF was also found to be the only antigen unaffected by exposure to sodium lauryl sulfate (SLS) and 2-mercaptoethanol (2-ME) (3); further, exposure of standard dengue-1 and dengue-2 sucrose-acetone antigens to SLS and 2-ME or 8M urea reduced the level of cross-reactions with other dengue serotypes.