RELATIONSHIP OF SEROTYPE, LEUKOTOXIN GENE TYPE AND LYSOGENY IN ACTINOBACILLUS-ACTINOMYCETEMCOMITANS TO PERIODONTAL-DISEASE STATUS

Actinobacillus actinomycetemcomitans has been associated with differen t forms of periodontitis, particularly with localized juvenile periodo ntitis (LJP). The bacterium possesses several virulence factors which have been shown to interact with the host immune system. Among these f actors, leukotoxin, surface antigens (serotype) and bacteriophages hav e been suggested directly or indirectly to influence the course of inf ection. However, few studies have been able to show associations betwe en these factors and periodontal disease, alone or in combination. Thu s, the purpose of the present study was to investigate possible correl ations between periodontal disease status and selected virulence facto rs (serotype, presence of bacteriophages, and the presence of a 530 bp deletion in the promotor region of the leukotoxin gene). 36 subjects took part in the study. Serotype c was the most frequently found serot ype among periodontally affected subjects, although serotypes a and b were also present. 27 out of 36 strains harbored bacteriophages, and t here was strong evidence that some of the bacteriophages were differen t from the previously characterized phi Aa phage. A. actinomycetemcomi tans containing the F-fragment phage were more frequently associated w ith periodontal disease. Five strains, all serotype b, 3 from LJP pati ents and 2 from healthy subjects, showed a 530-bp deletion in the prom otor region of the leukotoxin gene.