title: [Detecting the level of Actinobacillus actinomycetemcomitans leukotoxin].
abstract: OBJECTIVE
  To detect the level of Actinobacillus actinomycetemcomitans (Aa) leukotoxin and distinguish the highly and the minimally toxic strains.
  
  
  METHODS
  The polymerase chain reaction (PCR) assay was used to detect the difference of the nucleotide sequence of Aa leukotoxic promoter. 68 Aa isolates were examined, including 17 serotype b, 42 serotype c and 9 serotype a strains. The positive control strains were the highly toxic strain JP2 and 7 minimally toxic strains such as ATCC43717; the negative control strains were 12 other species of reference strains.
  
  
  RESULTS
  The PCR fragments of JP2 was about 492 bp and that of the other Aa reference strains and 68 clinical isolates were 1,022 bp. PCR products not found in 12 other species.
  
  
  CONCLUSIONS
  All of the 68 clinical isolates were minimally toxic strains.
authors.affiliation: Research Institute of Stomatology, Beijing Stomatological Hospital, Beijing 100050, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: T
authors.initials: T
authors.lastname: Zhang
authors.forename: B
authors.initials: B
authors.lastname: Xiao
mesh_terms: D000293:Adolescent; D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans / Q000235:genetics* / Q000472:pathogenicity; D004269:DNA, Bacterial / Q000235:genetics; D005098:Exotoxins / Q000235:genetics*; D006801:Humans; D011401:Promoter Regions, Genetic / Q000235:genetics; D013045:Species Specificity; D014774:Virulence / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D005098:Exotoxins; C018579:leukotoxin