Abstract

For 28 of 31 arboviruses (34 strains) studied, satisfactory hemagglutinins were demonstrated after treatment of sucrose-acetone-extracted liver or brain preparations by either sonication alone or sonication plus trypsin treatment. The methods of antigen treatment are described, and the appearance of a “cellular agglutinin” under some conditions of trypsin treatment is reported. The procedure for hemagglutinin preparation seems to be consistent for any given virus, but variation is seen from virus to virus. Hemagglutination-inhibition testing of selected antigens indicates that sonication alone improves sensitivity, whereas further treatment with trypsin gives variable results.