Reactions of purified hemagglutinating antigens of flaviviruses with 19S and 7S antibodies.

The rapidly sedimenting hemagglutinin (RHA) representing the purified virion and the slower-sedimenting hemagglutinin (SHA) of several flaviviruses were separated and used in hemagglutination inhibition tests with the 19S (immunoglobulin M) and 7S (immunoglobulin G) immunoglobulin fractions of rabbit antisera, prepared against purified viral antigens or against crude virus pools. The antibody specificity in tests with RHA was identical to the specificity in those employing SHA. 7S antibody cross-reacted broadly with all flavivirus antigens, whereas 19S antibodies were relatively specific in cross-reactions among flaviviruses (RHA or SHA). SHA was consistently inhibited by antibody to a greater extent than RHA. Anti-envelope protein, anti-RHA antibodies and anti-SHA antibodies were unable to discriminate between RHA and SHA. It was concluded that the relative amounts of RHA or SHA in crude hemagglutinin preparations have no influence on the result of hemagglutination inhibition tests with flaviviruses.