Inducible serum resistance in Salmonella typhimurium is dependent on wzz(fepE)-regulated very long O antigen chains.
Salmonella typhimurium possesses two wzz genes conferring long (wzz(ST)) and very long (wzz(fepE)) lipopolysaccharide O antigen modal chain lengths. While the long O antigen modal length was essential for complement resistance, the very long modal length was found to have a minor role. However, when grown in the presence of serum, S. typhimurium demonstrated a wzz(fepE)-dependent increase in the density of very long O antigen chains, resulting in a significant increase in serum resistance. Similar phenotypic changes were observed after growth under iron-limiting conditions, though iron limitation is unlikely to be the sole signalling mechanism behind the changes induced in serum. A wzz(fepE)::lacZ promoter fusion was used to determine that regulation of wzz(fepE) transcription is unlikely to be the mechanism behind the variation in O antigen length. Since systemic infection occurs in a small but significant percentage of human non-typhoid salmonellosis, the phenomenon identified in this study may be significant during the bacteraemic phase of infection.
Murray
Gerald L
GL
Australian Bacterial Pathogenesis Program, Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide 5005, Australia.
Attridge
Stephen R
SR
Morona
Renato
R
D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000032:analysis* / Q000276:immunology; D003165:Complement System Proteins / Q000276:immunology*; D003470:Culture Media / Q000737:chemistry; D007501:Iron / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D019081:O Antigens / Q000737:chemistry / Q000276:immunology*; D012486:Salmonella typhimurium / Q000276:immunology* / Q000472:pathogenicity; D014774:Virulence
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D003470:Culture Media; D019081:O Antigens; D003165:Complement System Proteins; D007501:Iron