FIG. 4.

Model for microevolution in the serotype b cluster consisting of 66 JP2 clone and 6 non-JP2 A. actinomycetemcomitans strains based on genetic variation revealed by multilocus sequence analysis and based on the assumptions described in the Results. The cluster of non-JP2 strains is indicated by cross-hatched ellipses, and the JP2 clone strains are indicated by solid ellipses. Each arrow in the model indicates a single mutation in the 4,143 nucleotides analyzed, and each mutation is indicated by the position in the HK1651 genome, the designation of the gene involved, and the nucleotide substitution. The 530-bp deletion in the ltx promoter is indicated by Δ530. Bacterial isolates from related family members in seven families are indicated, as are the countries of origin of the individuals from whom the JP2 clone isolates originated. If the individual was living in a country other than the country of origin, this is indicated after the small arrow. Isolates from individuals who originated in the Mediterranean area are indicated by a red dot, and isolates from individuals with a West African origin, including African-Americans from the United States, are indicated by a green square. No information about their origins was available for five JP2 clone-positive individuals, three living in the United States and two living in The Netherlands. Most of the JP2 strains from the United States were obtained from African-Americans; the only exceptions were three strains isolated from individuals of unknown descent (HK1199, HK1200, and HK1202). ψ, pseudogene.