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Evolution and comparative genomics of Campylobacter jejuni ST-677 clonal complex
Rauni I Kivistö1, Sara Kovanen2, Astrid Skarp-de Haan3
1Department of Food Hygiene and Environmental Health, University of Helsinki, Finland rauni.kivisto@helsinki.fi.
Genome Biology and Evolution
|September 7, 2014
Summary
This study analyzes the Campylobacter jejuni ST-677 clonal complex, a lineage linked to human bacteremia. Whole-genome sequencing revealed microevolution and identified potential virulence factors, offering insights into pathogenesis and adaptation.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Campylobacter is a leading cause of bacterial gastroenteritis in the EU, with over 200,000 cases annually.
- The sequence type (ST)-677 clonal complex (CC) of Campylobacter jejuni is associated with human bacteremia.
- Limited genomic data exists for the ST-677 CC, hindering understanding of its virulence and adaptation.
Purpose of the Study:
- To perform comparative genomics on the C. jejuni ST-677 CC to understand microevolution.
- To identify novel putative virulence determinants within the ST-677 CC lineage.
- To compare ST-677 CC genomes with reference strains and related species.
Main Methods:
- Whole-genome sequencing of five ST-677 CC isolates from chicken farms using Illumina HiSeq.
- Comparative genomic analysis of ST-677 CC isolates against C. jejuni reference strains.
- Homology-based searches for novel genetic features and virulence factors.
Main Results:
- The ST-677 CC is a highly clonal lineage with minor genomic differences, primarily in homopolymeric tracts affecting capsule, lipo-oligosaccharide, and flagella genes.
- Genomic features shared with C. jejuni subsp. doylei, including a degraded cytolethal distending toxin operon and similar capsular polysaccharide loci, were identified.
- Novel putative virulence factors, including two type Vb secretion systems and a restriction modification/methyltransferase gene cluster, were discovered.
Conclusions:
- The ST-677 CC exhibits microevolutionary changes relevant to its adaptation and potential virulence.
- The phase-variable GDP-mannose 4,6-dehydratase may enhance survival in host environments.
- The identified novel genetic elements contribute to understanding the pathogenesis and niche adaptation of this important C. jejuni lineage.
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