The use of liposomes for detection of the surface lipopolysaccharide antigen, Vibrio cholerae cells, and antibodies against them

A test system for determination of Vibrio cholerae cells, surface O-antigen, and antibodies against them was developed on the basis of complement-dependent lysis of liposomes sensitized by the lipopolysaccharide-dependent antigen from Vibrio cholerae 569B. The factors that affect the function of the liposomal reagent were studied, and the conditions for detecting antibodies and antigenic material were optimized. This system is highly specific and sensitive to be used for the determination of anticholeraic antibodies (30-50 times as effective as agglutination tests), lipopolysaccharide antigen (100 ng/ml, which corresponded to 3.0 ng of lipopolysaccharide in the sample studied), and Vibrio cholerae cells (3.3 x 10(7) m.b./ml, which corresponded to 10(6) m.b. in sample). It takes 30-40 min to detect the lipopolysaccharide antigen and 90 min to detect V. cholerae cells.