Occurrence of temperate bacteriophages in different Actinobacillus actinomycetemcomitans serotypes isolated from periodontally healthy individuals

Abstract

The occurrence of temperate bacteriophages was studied in 34 isolates of Actinobacillus actinomycetemcomitans derived from 27 periodontally healthy Finnish individuals both by lysis/plaque assays and by DNA hybridizations. In addition the serotype, the ribotype and the arbitrarily primed polymerase chain reaction (AP-PCR) profile were determined for each A. actinomycetemcomitans strain. Fourteen isolates showed hybridization patterns very similar to that of a known lysogen when probed with the genome of the previously characterized temperate phage Aa phi 23. Only 6 of these 14 strains had produced lysis or single plaques on suitable indicator strains. Phage Aa phi 247 derived from one of these lysogens was indistinguishable from Aa phi 23 by electron microscopy, and the genomes showed highly related DNA hybridization patterns. The remaining 20 isolates exhibited hybridization patterns very different from that of Aa phi 23 DNA. Seven of these strains also gave lysis or single plaques, suggesting that 21 of the 34 strains were lysogenic. These data indicate that the prophages per se do not represent a virulence factor exclusively associated with periodontal disease. Presence of an Aa phi 23-related prophage correlated with serotype a and AP-PCR type 1 of the bacterial host. This may indicate that Aa phi 23 and related phages have a limited host range.

Transduction of antibiotic resistance markers among Actinobacillus actinomycetemcomitans strains by temperate bacteriophages Aa ? 23

“…Its relations to the similar, inducible phage Aa isolated in North America [11] have not been determined. There was a high prevalence (44%) of temperate bacteriophages among Aa isolates from periodontally healthy oral cavities most of which were related to phage Aa23 [12]. So far there are no epidemiological or clinical indications that this phage alone would significantly increase the virulence of the Aa host [13,14].…”

“…Chromosomal DNA of transduced Aa strains was obtained with a genomic DNA purification kit (Qiagen AG). Digestion with restriction endonucleases (Boehringer Mannheim, Rotkreuz, Switzerland), separation of the fragments by agarose gel electrophoresis and the alkaline transfer [19] to nylon membranes (Biodyne A, Pall, Wohlen, Switzerland) were performed according to [12]. The probes used in Southern hybridizations were prepared as follows: polymerase chain reaction (PCR) products were directly labelled and used in hybridization procedures.…”

Prophage induction in lysogenic Aggregatibacter actinomycetemcomitans cells co-cultured with human gingival fibroblasts, and its effect on leukotoxin release

“…Furthermore, lysogeny has been reported to be associated with Aa strains isolated from subgingival sites exhibiting active periodontal disease [5], although this has been questioned in another study [6]. The frequent occurrence of lysogeny among strains of Aa associated with periodontal disease may be of considerable importance.…”

Complete Genomic Nucleotide Sequence of the Temperate Bacteriophage AaΦ23 of Actinobacillus actinomycetemcomitans

“…The role of phages in the etiology of periodontal diseases is not yet clear. Specifically, members of the Aa⌽23 family of phages have been found in about 40% of the A. actinomycetemcomitans isolates (11,15,25,38), and Aa⌽23 was shown to transduce antibiotic resistance markers in vitro (39). In several bacterial species, such as Vibrio cholerae (17,36) and Escherichia coli (24), phage-encoded genes modulate virulence.…”

“…Lysogenic A. actinomycetemcomitans isolates have been isolated from periodontal pockets (11,15,30,33) as well as from periodontally healthy individuals (38). The role of phages in the etiology of periodontal diseases is not yet clear.…”