[Dependence of immunosuppressive action of lipopolysaccharide on degree of Salmonella pathogenicity].
Immunosuppressive activity of Salmonella typhimurium extracellular lipopolysaccharide (LPS) was studied. In this study isogenic S. typhimurium strains with different degree of virulence were used. The attenuation of these strains was linked with mutations on their chromosome (altered synthesis of RNA polymerase or gyrase DNA) or their own virulence plasmid (the insertion of transposon Tn-5). To obtain LPS fraction with different molecular weights, the filtrate of bacterial culture was subjected to gel filtration through a column packed with Sephadex G-200. The immunosuppressive action of LPS fractions was determined on the model of delayed-type hypersensitivity to nonbacterial antigen in experiments on BALB/c mice. The study revealed that transposon-mediated mutation on plasmid, accompanied by the attenuation of salmonellae, led to the loss of immunosuppressive activity of the high-molecular heat-sensitive component of LPS; only the second heat-resistant component with medium molecular weight retained its activity. The presence of two chromosomal attenuating mutations (rifr nalr) was accompanied by the loss of immunosuppressive activity in both components of LPS.
Gromashevsky Research Institute of Epidemiology and Infectious Diseases, Kiev, Ukraine.
E V
EV
Borisova
V M
VM
Bondarenko
O S
OS
Molozhavaia
V A
VA
Borisov
D000818:Animals; D008070:Lipopolysaccharides / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010957:Plasmids; D012486:Salmonella typhimurium / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
D008070:Lipopolysaccharides