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A competitive ELISA using the intact toxin as a coating antigen for detecting palytoxin was developed. This immunoassay allows palytoxin (PTX) to be determined in the range of 6-250 ng/ml. In sensitivity, this determination is comparable with RIA but is three times inferior to ELISA using monoclonal antibodies. Inhibition experiments using some toxins of marine invertebrates proved the serological specificity of the palytoxin binding to antibodies. Both the indirect and competitive ELISA were used to find PTX-producing bacteria among 420 isolates of sea bacteria. It was found that gram-negative bacteria Aeromonas sp. and Vibrio sp. associated with toxic samples of the soft coral Palythoa sp. produced compounds antigenically related to PTX.

The protein moiety of endotoxin from Yersinia pseudotuberculosis was found to consist of two polypeptides with apparent molecular masses 40 and 14.5 kDa (4:1 w/w). The major protein (40 kDa) was isolated from the endotoxin pretreated with sodium deoxy cholate by gel chromatography on the Sephadex G-200 column. Comparative study of this protein and oligomeric form of porin from the outer membrane of Y. pseudotuberculosis using SDS--PAGE, velocity sedimentation, lipid bilayer experiments, chemical and serological analyses revealed their identity. The deoxycholate treatment of the endotoxin does not affect complexes of the major protein and LPS.

An O-specific polysaccharide from lipopolysaccharide of Yersinia intermedia pathogenic strain 680 has been isolated and shown to be a serologically active fructane. Serological specificity of the lipopolysaccharide and the fructane was studied by reactions of precipitation and of inhibition of passive hemolysis. On the basis of methylation studies, 13C NMR spectroscopy, and immunochemical data the following structure was proposed for the repeating unit of the O-specific polysaccharide: (Formula: see text)

Using spectroscopic methods (circular dichroism and intrinsic protein fluorescence) and immunoenzyme assay, changes in the spatial and antigenic structure of yersinin, porin from outer membrane of Yersinia pseudotuberculosis, were studied in solutions of ionic and non-ionic detergents at various temperatures and low pH values. Yersinin was shown to retain its secondary structure under various denaturation conditions, the content of regular structural patterns depending on specific action of the denaturation agent. Process of yersinin denaturation similarly to other membrane proteins appears to occur via two structural transitions: dissociation of oligomers and denaturation of monomers. At the first stage changes of quaternary structure accompanied by the loss of so called conformational determinants were observed. Temperature-dependent changes of monomers' tertiary structure affect antigenic activity of yersinin in a smaller degree.

Two forms of lipopolysaccharide-protein complex with buoyant densities of 1,43 and 1,40 g/cm3 were found in the Yersinia pseudotuberculosis cell wall. These forms have the similar monosaccharide, fatty acid and polypeptide compositions, but differ in the length of O-specific chains. The differences in density are stipulated by the different contents of the main components of the complex. Both forms contain the related antigenic determinants but have some differences in the antigenic structure. The ability of the two forms to produce a hybrid form with the intermediate density of 1,41 g/cm3 has been shown.