PREVALENCE AND DISTRIBUTION OF BACTERIOPHAGE-PHI-AA DNA IN STRAINS OFACTINOBACILLUS-ACTINOMYCETEMCOMITANS

phi Aa is a bacteriophage that was originally isolated by induction of a lysogenic strain of the oral bacterium Actinobacillus actinomycetem comitans. Since the discovery of phage phi Aa, additional phages infec ting several other strains of A. actinomycetemcomitans have been ident ified. To determine the prevalence of phi Aa or phi Aa-related tempera te phases in this species, a phi Aa-specific DNA probe was prepared to screen for homologous sequences among 42 strains of A. actinomycetemc omitans. Fourteen (33%) of the 42 strains examined contained DNA seque nces that hybridized with the phage phi Aa probe. A bacteriophage desi gnated phi Aa(33384) was isolated by induction from one of the strains (ATCC 33384) that contained a sequence that hybridized with the phi A a probe. The phi Aa probe hybridized with the DNA extracted from bacte riophage phi Aa(33384). The distribution of the phage phi Aa sequence among A. actinomycetemcomitans serotypes was 5/13 (38%) of the serotyp e a strains, 0/16 (0%) of the serotype b strains, and 9/13 (69%) of th e serotype c strains. The results of this investigation suggest that t he target sequence prepared from the phage phi Aa genome is fairly com mon in the A. actinomycetemcomitans chromosome, and that the sequence is distributed among the A. actinomycetemcomitans serotypes in a seemi ngly nonrandom manner.