Analysis of Vibrio parahaemolyticus soluble antigens by employing passive hemagglutination.

The passive hemagglutination assay was explored as a sensitive test of immunological reactivity of endotoxin and other antigens prepared from selected strains of Vibrio parahaemolyticus. The tannic acid procedure for passive hemagglutination, commonly used with protein antigens, was the only procedure yielding good results with V. parahaemolyticus protein extracts, endotoxins, and related preparations. These results were probably due to the presence of large amounts of protein in the V. parahaemolyticus endotoxins as determined by earlier work referenced in the text. Glucose and galactose as possible antigenic determinants in the endotoxin of a Vibrio strain were tested by inhibition tests. Cross-reactions were observed between endotoxin preparations, but were low in hemagglutination, suggesting reactions of common generic antigens. The ability of V. parahaemolyticus endotoxins to stimulate production of antibodies was determined.