Surface charge of dengue virus hemagglutinins prepared from infected mouse brains.

Surface charge of dengue virus hemagglutinin (HA) prepared from infected suckling mouse brains was studied by sucrose gradient electrophoresis. The findings were as follows: (1) Both the slow- and rapid-sedimenting hemagglutinins (SHA and RHA, respectively) prepared after streptomycin treatment of the brain homogenate were distributed broadly within the gradient after electrophoresis, while echovirus type 7 HA which was used as a reference migrated narrowly, suggesting heterogeneity of the surface charge of both dengue HAs. (2) Neuraminidase treatment of dengue HA slightly retarded its migration toward the anode but did not alter the broad distribution. (3) Protamine treatment used for purification of HA from the brain homogenate changed the surface charge from negative to positive.