[The use of solid-phase liposomal immunoassay for determining a bacterial antigen of lipopolysaccharide nature]

The solid-phase liposomal immunoassay procedure for the determination of Francisella tularensis lipopolysaccharide (LPS) has been developed. This assay has been made with the use of monolayer liposomes, on the average, 360 nm in diameter with their phospholipid bilayer modified with F. tularensis LPS and their internal space filled with calcein used as fluorescent marker. The assay is based on the principle of the competitive immunosorption of liposomes and antigenic LPS on the surface of polystyrene plates sensitized with specific monoclonal antibodies. The dynamic range of the method is 50-2,500 mg/ml, the variation index being 2.3-11.5%. Optimization of this method and its comparison with the enzyme immunoassay system for the given antigen-antibody pair has been made.