Specific detection of Salmonella enterica and Escherichia coli strains by using ELISA with bacteriophages as recognition agents.

The use of bacteriophages, instead of antibodies, in the ELISA-based detection of bacterial strains was tested. This procedure appeared to be efficient, and specific strains of Salmonella enterica and Escherichia coli could be detected. The sensitivity of the assay was about 10(5) bacterial cells/well (10(6)/ml), which is comparable with or outperforms other ELISA tests detecting intact bacterial cells without an enrichment step. The specificity of the assay depends on the kind of bacteriophage used. We conclude that the use of bacteriophages in the detection and identification of bacteria by an ELISA-based method can be an alternative to the use of specific antibodies. The advantages of the use of bacteriophages are their environmental abundance (and, thus, a possibility to isolate various phages with different specificities) and the availability of methods for obtaining large amounts of phage lysates, which are simple, rapid, cheap, and easy.

Heterogeneous structure of O-Antigenic part of lipopolysaccharide of Salmonella Telaviv (Serogroup O:28) containing 3-Acetamido-3,6-dideoxy-D-glucopyranose.

The O-polysaccharide of Salmonella Telaviv was obtained by mild acid degradation of the lipopolysaccharide and studied by chemical methods (sugar and methylation analyses, Smith degradation, de-O-acetylation) and NMR spectroscopy. The structure of the O-polysaccharide was established. The repeating units that are proximal to the lipopolysaccharide core region mostly have a digalactose side chain and lack glucose, whereas those at the other end of the chain mostly do bear glucose but are devoid of the disaccharide side chain. This is the first structure established for the O-polysaccharide of a Salmonella serogroup O:28 (formerly M) strain characterized by subfactors O28(1) and O28(2). Knowledge of this structure and the structure of the O-polysaccharide of Salmonella Dakar (O28(1), O28(3)) established earlier is crucial for determination of the exact structures associated with subfactors O28(1), O28(2), and O28(3) and elucidation of the genetic basis of the close relationship between Escherichia coli O71 and S. enterica O:28 O-antigens.

Immunological and chemical studies of Salmonella haarlem somatic antigen epitopes. II. Serological investigations.

Lipopolysaccharide of Salmonella haarlem was hydrolyzed and the products separated. Native O-polysaccharide antigen was oxidised with sodium periodate followed by reduction with sodium borohydride. Native and chemically modified antigens were the subject of immunochemical studies. Monoclonal antibodies against S. haarlem and polyclonal rabbit antisera against S. haarlem, S. typhi and S. anatum bacteria were produced. The serological relationship between the lipopolysaccharide of Salmonella bacteria belonging to the two different groups D2 and E1 was demonstrated using haemagglutination reactions, inhibition of haemagglutination and immunoblotting. Cross-reactions were observed in haemagglutination reactions and in immunoblotting between antisera to S. haarlem, S. typhi and S. anatum. Factors 3,9,46 were found in the S. haarlem strain and the sugar composition for the epitopes of each factor was determined.

Immunological and chemical studies of Salmonella haarlem somatic antigen epitopes. I. Structural studies of O-antigen.

Lipopolysaccharide (LPS) of Salmonella haarlem was hydrolyzed and the products separated. The structure of the O-specific polysaccharide (OPS) was found from sugar and methylation analyses. Rhamnose, mannose, galactose and tyvelose were detected and their linkage modes were established. The structure was confirmed by 1H, homonuclear and heteronuclear correlations and 13C NMR spectra. Anomeric configurations were assigned by chromium trioxide oxidation and proton coupled 13C spectra. Sugar sequence was established from specific carbon shift data and nuclear Overhauser effect spectroscopy. The repeating unit structure of S. haarlem OPS as --> 3)-alpha-D-Galp-(1 --> 6)-[alpha-Tyvp-(1 --> 3)]-beta-D-Manp-(1 --> 4)-alpha-L-Rhap was estimated. No structural heterogeneity of the antigen was found.

The epidemiological situation of Salmonella enteritidis in Poland.

The epidemiological situation connected with S. enteritidis in Poland, in the years 1961-1991, is described. During this period there were two increases in infections and food poisonings, which were of an epidemiological character. The first epidemic, in 1962-1976, affected primarily small children and spread by contact in a hospital environment. It caused serious diseases, or dangerous complications in already existing illnesses, with high mortality. A few foci of later food poisonings were caused by infected meat or meat by-products. The second epidemic, which began in 1980 or 1981 and still exists, has already affected about 500,000 persons. It has often concerned cases of sporadic infections, mainly in the case of small children, but it has not been of a hospital epidemic character. It has been far more frequently associated with food poisoning outbreaks caused by contaminated ice-cream, cream cakes, eggs, mayonnaise and, less frequently, by meat and meat by-products. Attention is drawn to the large number of humans transmitting S. enteritidis infections in Poland.

The action of the Yersinia pestis phage on the plague envelope antigen and the human erythrocytes.

The activity of the Yersinia pestis phage on the plague envelope antigen has been described. The purified envelope antigen was shown to possess the receptor properties. The phage caused changes of viscosity and hemagglutination properties of the antigen. The phage-treated antigen showed the additional precipitation arc in the immunoelectrophoretic investigations. The adsorption of the Yersinia pestis phage on the sheep and human erythrocytes was examined. The human red cells of group B exhibited the highest receptor properties for the Yersinia pestis phage.

Monoclonal antibodies against Vi antigen production and characterization.

As a result of fusion of in vitro immunized mouse splenocytes and myeloma Sp2/0 cells, stable hybridomas secreting monoclonal antibodies against Vi antigen were obtained. The monoclonal antibodies were of IgM class. Reactivity of monoclonal antibodies to Vi antigen of different origin was tested. The reactivity was found to be independent of O-acetylation degree of Vi antigen.

Distribution of Salmonella enteritidis phage-types in Poland in 1981-1990.

The occurrence of S. enteritidis phage types in Poland during the years 1981-1990 was examined. The strains were isolated from man, animals, and from food-stuffs. The majority of strains belongs to the phage types 7 and 1. The comparison with the phage-types isolated in 1970-1975 in Poland is done. The stability of the phage types in reported outbreaks is considered.