Effects of SequentialCampylobacter jejuni81-176 Lipooligosaccharide Core Truncations on Biofilm Formation, Stress Survival, and Pathogenesis

Abstract

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 ⌬galT and ⌬cstII mutants with more minor LOS truncations. Interestingly, we found that mutants lacking the LOS outer core (⌬waaF and ⌬lgtF but not ⌬galT or ⌬cstII 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 (⌬cstII), 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 ⌬waaF 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.

The Campylobacter jejuni Transcriptional Regulator Cj1556 Plays a Role in the Oxidative and Aerobic Stress Response and Is Important for Bacterial SurvivalIn Vivo

“…A modification of the interaction and invasion assays was used to analyze the level of intracellular survival in Caco-2 intestinal epithelial cells (53) in order to investigate the ability of C. jejuni to survive when exposed to intracellular stress conditions, such as ROS. There was a statistically significant reduction in the level of intracellular survival of the Cj1556 mutant compared to the 11168H wild-type and Cj1556 complement strains (Fig.…”

Glycan:glycan interactions: High affinity biomolecular interactions that can mediate binding of pathogenic bacteria to host cells

“…Previous studies of these four pathogens have linked LOS/LPS to adherence/virulence with full-length LOS/LPS for each of these organisms is absolutely required for virulence in animal models (40)(41)(42)(43). S. flexneri LPS O-antigen is a virulence factor whose chain length affects both serum resistance and the function of surface virulence factors; a role for LPS in cell invasion has been reported (11,(44)(45)(46).…”

Lipooligosaccharide Core Truncations Affect the Ability of <i>Campylobacter</i> <i>jejuni</i> to Attach to Glass and Form Biofilms under Aerobic Conditions

“…The effects of LOS core truncations on biofilm formation by C. jejuni have not been investigated under aerobic conditions. However, the LOS core truncations caused by waaF or lgtF mutations reportedly enhanced biofilm formation by C. jejuni strain 81-176 under microaerobic conditions (Naito et al 2010). In contrast, the LOS core truncations caused by galT or cstII (cjj1157) mutations did not affect biofilm formation by this strain under the same growth conditions (Naito et al 2010).…”

“…However, the LOS core truncations caused by waaF or lgtF mutations reportedly enhanced biofilm formation by C. jejuni strain 81-176 under microaerobic conditions (Naito et al 2010). In contrast, the LOS core truncations caused by galT or cstII (cjj1157) mutations did not affect biofilm formation by this strain under the same growth conditions (Naito et al 2010). These results suggest that different LOS core truncations have distinct impacts on biofilm formation by C. jejuni under microaerobic conditions.…”

“…The LOS core truncations caused by waaF or lgtF mutations have been shown to enhance biofilm formation by C. jejuni 81-176 under microaerobic conditions (Naito et al 2010). However, under aerobic conditions, these results were only achieved for the NCTC 11168 strain and not the 81-176 strain, which suggests that the incubation conditions may affect the role of the LOS core in biofilm formation by C. jejuni.…”