Role of capsule and O antigen in the virulence of uropathogenic Escherichia coli.
Urinary tract infection (UTI) is one of the most common bacterial infections in humans, with uropathogenic Escherichia coli (UPEC) the leading causative organism. UPEC has a number of virulence factors that enable it to overcome host defenses within the urinary tract and establish infection. The O antigen and the capsular polysaccharide are two such factors that provide a survival advantage to UPEC. Here we describe the application of the rpsL counter selection system to construct capsule (kpsD) and O antigen (waaL) mutants and complemented derivatives of three reference UPEC strains: CFT073 (O6:K2:H1), RS218 (O18:K1:H7) and 1177 (O1:K1:H7). We observed that while the O1, O6 and O18 antigens were required for survival in human serum, the role of the capsule was less clear and linked to O antigen type. In contrast, both the K1 and K2 capsular antigens provided a survival advantage to UPEC in whole blood. In the mouse urinary tract, mutation of the O6 antigen significantly attenuated CFT073 bladder colonization. Overall, this study contrasts the role of capsule and O antigen in three common UPEC serotypes using defined mutant and complemented strains. The combined mutagenesis-complementation strategy can be applied to study other virulence factors with complex functions both in vitro and in vivo.
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.
Sohinee
S
Sarkar
School of Medical Sciences, Griffith Health Institute, Griffith University, Gold Coast, Queensland, Australia.
Glen C
GC
Ulett
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.
Makrina
M
Totsika
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.
Minh-Duy
MD
Phan
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.
Mark A
MA
Schembri
D000818:Animals; D000942:Antigens, Bacterial / Q000378:metabolism*; D016667:Bacterial Capsules / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000276:immunology / Q000382:microbiology*; D029968:Escherichia coli Proteins; D051379:Mice; D019081:O Antigens / Q000235:genetics / Q000378:metabolism*; D000091243:Ribosomal Protein S9; D014552:Urinary Tract Infections / Q000276:immunology / Q000382:microbiology*; D056689:Uropathogenic Escherichia coli / Q000276:immunology / Q000472:pathogenicity*; D014774:Virulence
D000942:Antigens, Bacterial; D029968:Escherichia coli Proteins; D019081:O Antigens; D000091243:Ribosomal Protein S9; C000717190:RpsI protein, E coli