Salmonella typhi, lipopolysaccharide

It contains the attenuated strain Ty21a of Salmonella typhi. The attenuation is due to the absence of enzyme uridine diphosphate galactose-4-epimerase which is essential for the production of the lipopolysaccharide O antigen. The absence of this enzyme makes Ty21a highly immunogenic. 

Terminal 3,6-dideoxyhexoses that occur in lipopolysaccharides from Salmonella and Yersinia (Pasteurella) species7 could be hydrolyzed off with a high degree of selectivity. They may, therefore, be located by methylation analysis of the original lipopolysaccharide and of a partially hydrolyzed sample. Thus, for the Salmonella typhi-murium 395 MS lipopolysaccharide, composed18 of oligosaccharide... 

The method has also been applied to acetylated polysaccharides. Thus, whereas the D-mannopyranose residue in the acetylated lipo-polysaccharide from Salmonella typhi was found to be inert, that in Salmonella Strasbourg was oxidized, demonstrating that the former is a-D-linked and the latter /3-D-linked.154 The D-mannose residues in the acetylated lipopolysaccharide from Klebsiella O-group 3 were found resistant to oxidation, and are consequently a-D-linked."... 

Baker, S., Gunn, J., Morona, R. The Salmonella typhi melittin resistance gene pqaB affects intracellular growth in PMA-differentiated U937 cells, polymyxin B resistance and lipopolysaccharide. Microbiology 145 (1999) 367-378. 

A two-component regulatory system has been characterized that is involved in the resistance of P. aeruginosa in response to external magnesium concentrations (26). Similarly, the PmrA/PmrB two-component system of Salmonella enterica that mediates modifications in the lipopolysaccharide, resulting in resistance to polymyxins, has been characterized in more detail (27). The pqaB locus affected polymyxin B resistance in Salmonella typhi (28). 

Salmonella typhi contain antigen O (somatic) and antigen H (flagellar) which give rise to host antibodies. The antigens are lipopolysaccharides which are located in the outer membrane of Salmonella baciUi. Salmonella typhi is further identified by the additional presence of antigen Vi (capsular). A fourfold or over rise of antibody titers to O and H antigens. A 2-weeks apart in paired samples is indicative of typhoid fever. 

An example is the structural elucidation of the lipopolysaccharide from Salmonella typhi. It contains n-glucose, n-galactose, o-mannose, l-... 

Isol. from various lipopolysaccharides elaborated by Gram-negative bacteria, e.g. Salmonella typhi. 

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