THE DIFFERENTIATION OF BORDETELLA-PARAPERTUSSIS AND BORDETELLA-BRONCHISEPTICA FROM HUMANS AND ANIMALS AS DETERMINED BY DNA POLYMORPHISM MEDIATED BY 2 DIFFERENT INSERTION-SEQUENCE ELEMENTS SUGGESTS THEIR PHYLOGENETIC RELATIONSHIP

We describe a novel insertion sequence (IS) element, IS1002, which was found to be closely related to IS481, which is found only in Bordetel la pertussis; we found that these two IS elements have a level of sequ ence identity of 61.5% and also have almost identical terminal inverte d repeats, IS1002 was present in both B. pertussis and Bordetella para pertussis strains isolated from humans, In contrast, IS1002 was absent from B. parapertussis strains isolated from sheep, A DNA fingerprint analysis performed with another IS element, IS1001, which is present i n B. parapertussis and Borderella bronchiseptica, revealed that B. par apertussis isolates obtained from sheep are distinct from human isolat es, Thus, human and ovine B. parapertussis strains comprise two distin ct populations, indicating that little or no transmission occurs betwe en sheep and humans. An IS-associated restriction fragment length poly morphism analysis revealed that B. parapertussis strains isolated from sheep are genetically more polymorphic than the human B. parapertussi s population, which is genetically very homogeneous. This suggests tha t human B. parapertussis strains diverged from a single clone only rec ently. IS1001 is present in a subset of B. bronchiseptica strains that were derived mainly from pigs and rabbits, suggesting that these stra ins had a common ancestry, On the basis of the results of a comparison of IS1002 band patterns and IS1001 sequences, ovine and human B. para pertussis strains appear to have evolved independently from B. bronchi septica strains and to have adapted to different hosts (sheep and huma ns), Once in the human host, B. parapertussis probably acquired IS1002 from B. pertussis. In contrast to human B. parapertussis isolates, B. pertussis strains produced polymorphic IS1002-related DNA fingerprint patterns.