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Involvement of a plasmid in virulence of Campylobacter jejuni 81-176.

ABSTRACT: Campylobacter jejuni strain 81-176 contains two, previously undescribed plasmids, each of which is approximately 35 kb in size. Although one of the plasmids, termed pTet, carries a tetO gene, conjugative transfer of tetracycline resistance to another strain of C. jejuni could not be demonstrated. Partial sequence analysis of the second plasmid, pVir, revealed the presence of four open reading frames which encode proteins with significant sequence similarity to Helicobacter pylori proteins, including one encoded by the cag pathogenicity island. All four of these plasmid-encoded proteins show some level of homology to components of type IV secretion systems. Mutation of one of these plasmid genes, comB3, reduced both adherence to and invasion of INT407 cells to approximately one-third that seen with wild-type strain 81-176. Mutation of comB3 also reduced the natural transformation frequency. A mutation in a second plasmid gene, a virB11 homolog, resulted in a 6-fold reduction in adherence and an 11-fold reduction in invasion compared to the wild type. The isogenic virB11 mutant of strain 81-176 also demonstrated significantly reduced virulence in the ferret diarrheal disease model. The virB11 homolog was detected on plasmids in 6 out of 58 fresh clinical isolates of C. jejuni, suggesting that plasmids are involved in the virulence of a subset of C. jejuni pathogens.

SUBMITTER: Bacon DJ

PROVIDER: S-EPMC98329 | biostudies-literature | 2000 Aug

REPOSITORIES: biostudies-literature

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Involvement of a plasmid in virulence of Campylobacter jejuni 81-176.

Bacon D J DJ Alm R A RA Burr D H DH Hu L L Kopecko D J DJ Ewing C P CP Trust T J TJ Guerry P P

Infection and immunity 20000801 8

Campylobacter jejuni strain 81-176 contains two, previously undescribed plasmids, each of which is approximately 35 kb in size. Although one of the plasmids, termed pTet, carries a tetO gene, conjugative transfer of tetracycline resistance to another strain of C. jejuni could not be demonstrated. Partial sequence analysis of the second plasmid, pVir, revealed the presence of four open reading frames which encode proteins with significant sequence similarity to Helicobacter pylori proteins, inclu ...[more]

PMID: 10899834

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Project description: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.

Dataset Information

Involvement of a plasmid in virulence of Campylobacter jejuni 81-176.

Publications

Involvement of a plasmid in virulence of Campylobacter jejuni 81-176.

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