Figure 4. . IS100 and IS1541 restriction fragment length polymorphism patterns of 70 Yersinia pestis isolates of worldwide origin. A) Medievalis branch. B), ancient strain from Algeria (IP1867); C) other strains from Algeria and various isolates from Africa. The dendrogram was constructed by using the unweighted pair group method with arithmetic mean clustering analysis and a position tolerance of 1.8%. Biovar is shown on the right. UN, unknown; ND, not determined.