Molecular Genetics and the Analysis of Leukotoxin in <i>A. actinomycetemcomitans</i>

Kolodrubetz, David J

doi:10.1902/jop.1996.67.3s.309

Cited by 10 publications

(8 citation statements)

References 47 publications

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“…To elucidate further the role of iron availability in the regulation of the leukotoxin production, a constructed A. actinomycetemcomitans strain with the 530‐bp deletion of the ltx operon and in addition with a leukotoxin β‐galactosidase “reporter” gene recombined into the chromosome at the leukotoxin locus, has been used ( Spitznagel et al, 1995). However, the production of leukotoxin by this A. actinomycetemcomitans mutant was not influenced by the level of iron in the media ( Spitznagel et al, 1995, Kolodrubetz , 1996). These results are in contrast to other findings concerning RTX‐toxins, e.g., Mannheimia haemolytica leukotoxin production has been found to be down‐regulated by iron restriction ( Strathdee & Lo , 1989B).…”

Section: The Leukotoxin Of a Actinomycetemcomitansmentioning

confidence: 84%

The highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans: evolutionary aspects, epidemiology and etiological role in aggressive periodontitis

Haubek

2010

APMIS

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For many years, attention has been given to the oral bacterium Aggregatibacter actinomycetemcomitans, as a species possibly implicated in the etiology of aggressive periodontitis in adolescents. One of the major virulence factors of A. actinomycetemcomitans is the leukotoxin which is able to kill important cells of the immune system. As demonstrated in population genetic analyses, the population structure of A. actinomycetemcomitans is mainly clonal with evolutionary lineages corresponding to the serotypes. A particular highly leukotoxic clone (JP2) of serotype b has been discovered. The JP2 clone, with an estimated origin some 2400 years ago, is found to be highly conserved, based on analyses of a collection of JP2 clone strains collected through more than 20 years from individuals of diverse origin and living geographically widespread. Despite demonstration of minor evolutionary changes within the genome of JP2 clone strains of A. actinomycetemcomitans, the JP2 clone strains constitute a unique clonal type, the characteristics of which include a 530 basepair deletion in the leukotoxin operon implicated in the enhanced leukotoxic activity of the clone. Mapping of the geographic occurrence of the JP2 clone of A. actinomycetemcomitans has revealed that its colonization is largely restricted to individuals of African descent. Characteristic mutations, which allow JP2 clone isolates from the Mediterranean region to be distinguished from isolates from West Africa, including the Cape Verde islands, suggest that the JP2 clone initially emerged as a distinct genotype in the Mediterranean region of Africa and subsequently spread to West Africa, from where it might have been transferred to the American continent during the transatlantic slave trade. The finding of a sustained selective colonization of individuals of African descent, despite geographical separation from the African continent for centuries, suggests that the JP2 clone might have a distinct host tropism. Further studies are needed to elucidate the reasons for the apparent selective colonization of the Mediterranean and Western African populations. The JP2 clone of A. actinomycetemcomitans appears to play a prominent role in the etiology of aggressive periodontitis compared to other clonal types of the species. While A. actinomycetemcomitans, in general, is considered an opportunistic pathogen of the resident oral microbiota, the JP2 clone has features similar to those of an exogenous pathogen. Clonal types other than JP2 can be isolated from healthy as well as periodontally diseased individuals, whereas the JP2 clone has been isolated primarily from periodontally diseased individuals. As demonstrated in a prospective cohort study in Morocco, where the JP2 clone is endemically present, the presence of this clone in dental plaque confers a remarkably increased risk for development of aggressive periodontitis, suggesting that the JP2 clone is an important etiological agent of aggressive periodontitis in adolescents. Support for association of clonal types other...

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Section: The Leukotoxin Of a Actinomycetemcomitansmentioning

confidence: 84%

The highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans: evolutionary aspects, epidemiology and etiological role in aggressive periodontitis

Haubek

2010

APMIS

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“…A. actinomycetemcomitans is a facultative anaerobe while most of the other periodontopathogenic bacteria are obligate anaerobes (30,34). A. actinomycetemcomitans produces at least two types of cytotoxin, leukotoxin and now CDT, while most of the other periodontopathogenic bacteria produce no such strong cytotoxic proteins (8,14). Furthermore, A. actinomycetemcomitans has long been reported to produce immunosuppressing factor(s) (17,19,27,29), and the recent study suggested that CDT might be one of the candidates.…”

Section: Discussionmentioning

confidence: 99%

“…It produces a variety of virulence factors including cytotoxic factors (2, 8-12, 17, 19, 28, 31), chemotactic inhibitors (33), collagenases (24), and lipopolysaccharides (13,25). Among the cytotoxic factors, leukotoxin has been the most extensively studied (14)(15)(16)18). Recently, we and others discovered another cytotoxic factor which shows cell cycle-specific growth inhibitory activity as a new member of the cytolethal distending toxin (CDT) family in A. actinomycetemcomitans Y4 (18,28,32).…”

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confidence: 99%

Prevalence of Cytolethal Distending Toxin Production in Periodontopathogenic Bacteria

Yamano

Ohara²,

Nishikubo

et al. 2003

J Clin Microbiol

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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.Periodontitis is a destructive inflammatory response affecting the tooth-supporting tissues. Etiological and microbiological studies have well established that dental plaque, a composite of microorganisms and their products, plays a major role in the pathogenesis of periodontitis (2, 34). Previous evidence suggests that it participates in promoting inflammation of gingival tissue through direct cytotoxicity and indirect immunemediated responses (33). A variety of bacterial products in dental plaque have been implicated in this process. Actinobacillus actinomycetemcomitans has been suspected to be one of the key pathogens in the etiology of human periodontitis (30,34). It produces a variety of virulence factors including cytotoxic factors (2, 8-12, 17, 19, 28, 31), chemotactic inhibitors (33), collagenases (24), and lipopolysaccharides (13, 25). Among the cytotoxic factors, leukotoxin has been the most extensively studied (14-16, 18). Recently, we and others discovered another cytotoxic factor which shows cell cycle-specific growth inhibitory activity as a new member of the cytolethal distending toxin (CDT) family in A. actinomycetemcomitans Y4 (18, 28, 32). The CDTs are produced by a variety of bacterial genera and form a heterogeneous family of toxins with similar biological activities (4,20,23,26). The term CDT was designated for an activity that ind...

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“…Protein expression was confirmed by immunoblotting using anti‐Omp100 serum. Also, a conventional outer membrane preparation using sucrose gradient centrifugation (Kolodrubetz et al ., 1996) was performed to determine the localization of these truncated proteins. Using these strains, assays for adhesion, invasion and serum resistance were performed with the methods described elsewhere.…”

Section: Methodsmentioning

confidence: 99%

Outer membrane protein 100, a versatile virulence factor of Actinobacillus actinomycetemcomitans

Asakawa

Komatsuzawa²,

Kawai³

et al. 2003

Molecular Microbiology

121

126

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SummaryActinobacillus actinomycetemcomitans ( Aa ) is one of the pathogenic bacteria involved in periodontal diseases. We have previously identified six major outer membrane proteins (Omps) of Aa Y4. Among them is an Omp with high molecular mass, designated Omp100, which has homology to a variety of virulence factors. Electron microscopic observation indicated that Omp100 is randomly localized on the cell surface of Aa . Aa Y4 has been shown to adhere and invade KB or normal human gingival keratinocytes. AntiOmp100 antibody inhibited 50% of adhesion and 70% of invasion of Aa Y4 to KB cells. An Omp100 knockout mutant had a decreased adhesion and invasion efficiency of 60%, compared with that of the wild type. Escherichia coli HB101 expressing Omp100 adhered twofold and invaded 10-fold more than the wild-type E. coli HB101. HB101 expressing Omp100 showed resistance to serum by trapping factor H, an inhibitor for C3b, with Omp100. Omp100 induced inflammatory cytokine responses of interleukin (IL)-8, IL-6 and tumour necrosis factor (TNF) a a a a in epithelial cells, and induced IL-1 b b b b and TNF a a a a production in mouse macrophages. These results indicate that Omp100 is a versatile virulence factor that may demonstrate potential significance in the onset of periodontal diseases related to Aa .

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Molecular Genetics and the Analysis of Leukotoxin in A. actinomycetemcomitans

Cited by 10 publications

References 47 publications

The highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans: evolutionary aspects, epidemiology and etiological role in aggressive periodontitis

The highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans: evolutionary aspects, epidemiology and etiological role in aggressive periodontitis

Prevalence of Cytolethal Distending Toxin Production in Periodontopathogenic Bacteria

Outer membrane protein 100, a versatile virulence factor of Actinobacillus actinomycetemcomitans

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