Prevalence of cytolethal distending toxin production in periodontopathogenic bacteria.
Cytolethal distending toxin (CDT) is a newly identified virulence factor produced by several pathogenic bacteria implicated in chronic infection. Seventy three strains of periodontopathogenic bacteria were examined for the production of CDT by a HeLa cell bioassay and for the presence of the cdt gene by PCR with degenerative oligonucleotide primers, which were designed based on various regions of the Escherichia coli and Campylobacter cdtB genes, which have been successfully used for the identification and cloning of cdtABC genes from Actinobacillus actinomycetemcomitans Y4 (M. Sugai et al., Infect. Immun. 66:5008-5019, 1998). CDT activity was found in culture supernatants of 40 of 45 tested A. actinomycetemcomintans strains, but the titer of the toxin varied considerably among these strains. PCR experiments indicated the presence of Y4-type cdt sequences in these strains, but the rest of A. actinomycetemcomitans were negative by PCR amplification and also by Southern blot analysis for the cdtABC gene. In the 40 CDT-positive strains, Southern hybridization with HindIII-digested genomic DNA revealed that there are at least 6 restriction fragment length polymorphism types. This suggests that the cdtABC flanking region is highly polymorphic, which may partly explain the variability of the CDT activity in the culture supernatants. The rest of tested strains of periodontopathogenic bacteria did not have detectable CDT production by the HeLa cell assay and for cdtB sequences by PCR analysis under our experimental conditions. These results strongly suggested that CDT is a unique toxin predominantly produced by A. actinomycetemcomitans among periodontopathogenic bacteria.
Yamano
Ryousuke
R
Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, Minami-ku, Hiroshima 734-8553, Japan.
Ohara
Masaru
M
Nishikubo
Shuichi
S
Fujiwara
Tamaki
T
Kawamoto
Toru
T
Ueno
Yoko
Y
Komatsuzawa
Hitoshi
H
Okuda
Katsuji
K
Kurihara
Hidemi
H
Suginaka
Hidekazu
H
Oswald
Eric
E
Tanne
Kazuo
K
Sugai
Motoyuki
M
D000189:Actinobacillus Infections / Q000382:microbiology; D016976:Aggregatibacter actinomycetemcomitans / Q000378:metabolism* / Q000472:pathogenicity; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics; D002453:Cell Cycle; D006090:Gram-Negative Bacteria / Q000378:metabolism* / Q000472:pathogenicity; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006367:HeLa Cells; D006801:Humans; D010518:Periodontitis / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D014774:Virulence
D001427:Bacterial Toxins; C067044:cytolethal distending toxin