Effects of sequential Campylobacter jejuni 81-176 lipooligosaccharide core truncations on biofilm formation, stress survival, and pathogenesis.
Campylobacter jejuni is a highly prevalent human pathogen for which pathogenic and stress survival strategies remain relatively poorly understood. We previously found that a C. jejuni strain 81-176 mutant defective for key virulence and stress survival attributes was also hyper-biofilm and hyperreactive to the UV fluorescent dye calcofluor white (CFW). We hypothesized that screening for CFW hyperreactive mutants would identify additional genes required for C. jejuni pathogenesis properties. Surprisingly, two such mutants harbored lesions in lipooligosaccharide (LOS) genes (waaF and lgtF), indicating a complete loss of the LOS outer core region. We utilized this as an opportunity to explore the role of each LOS core-specific moiety in the pathogenesis and stress survival of this strain and thus also constructed DeltagalT and DeltacstII mutants with more minor LOS truncations. Interestingly, we found that mutants lacking the LOS outer core (DeltawaaF and DeltalgtF but not DeltagalT or DeltacstII mutants) exhibited enhanced biofilm formation. The presence of the complete outer core was also necessary for resistance to complement-mediated killing. In contrast, any LOS truncation, even that of the terminal sialic acid (DeltacstII), resulted in diminished resistance to polymyxin B. The cathelicidin LL-37 was found to be active against C. jejuni, with the LOS mutants exhibiting modest but tiled alterations in LL-37 sensitivity. The DeltawaaF mutant but not the other LOS mutant strains also exhibited a defect in intraepithelial cell survival, an aspect of C. jejuni pathogenesis that has only recently begun to be clarified. Finally, using a mouse competition model, we now provide the first direct evidence for the importance of the C. jejuni LOS in host colonization. Collectively, this study has uncovered novel roles for the C. jejuni LOS, highlights the dynamic nature of the C. jejuni cell envelope, and provides insight into the contribution of specific LOS core moieties to stress survival and pathogenesis.
Department of Microbiology and Immunology, University of British Columbia, Vancouver, V6T 1Z3 Canada.
Mizue
M
Naito
Emilisa
E
Frirdich
Joshua A
JA
Fields
Mark
M
Pryjma
Jianjun
J
Li
Andrew
A
Cameron
Michel
M
Gilbert
Stuart A
SA
Thompson
Erin C
EC
Gaynor
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D018938:Caco-2 Cells; D016123:Campylobacter jejuni / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008070:Lipopolysaccharides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D009154:Mutation; D011112:Polymyxin B / Q000494:pharmacology; D054804:Cathelicidins
D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D011112:Polymyxin B; D054804:Cathelicidins