Identification and characterization of a major subgroup of conjugative Campylobacter jejuni plasmids.
OBJECTIVE
Enterocyte invasion of Campylobacter jejuni 81-176 has been reported to depend upon the virulence plasmid pVir. The objective of this study was to determine the prevalence of pVir in clinical C. jejuni isolates, to investigate DNA homologies between C. jejuni plasmids and the significance of plasmids for C. jejuni invasiveness.


METHODS
DNA homologies between C. jejuni plasmids were studied by southern blot hybridization. C. jejuni invasion into human intestinal Caco-2 cells was assessed in a gentamicin exclusion assay.


RESULTS
Twenty-nine percent of C. jejuni isolated from patients with bloody or watery diarrhoea harboured plasmids of various sizes. One plasmid (7%) was a pVir homologue whereas, the majority of the plasmids (53%) belonged to a subgroup distinct from pVir. The plasmids of this novel subgroup share extensive DNA sequence homology with each other, including homologues to so-called invasion-promoting genes. However, conjugative transfer of these plasmids clearly did not increase invasiveness of plasmidless recipient C. jejuni strains.


CONCLUSIONS
This study indicates that only a small proportion of C. jejuni strains carry the virulence factor pVir and that at least one other distinctive group of plasmids in C. jejuni exists, which does not seem to be associated with invasiveness.
Schmidt-Ott
Ruprecht
R
Department of Bacteriology, University of Göttingen, Kreuzbergring 57, D-37075 Göttingen, Germany. rschmid1@gwdg.de
Pohl
Sven
S
Burghard
Sebastian
S
Weig
Michael
M
Gross
Uwe
U
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D018938:Caco-2 Cells; D002169:Campylobacter Infections / Q000382:microbiology; D016123:Campylobacter jejuni / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D003227:Conjugation, Genetic; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D003967:Diarrhea / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D037521:Virulence Factors; C024404:BglII endonuclease; D015252:Deoxyribonucleases, Type II Site-Specific