Mycoplasma arthritidis bacteriophage MAV1 prophage integration, deletions, and strain-related polymorphisms

Temperate bacteriophage MAV1 is found in certain highly virulent strains of Mycoplasma arthritidis. Integration sites, portions of the right and left prophage ends, and flanking DNA from eight prophages in seven M. arthritidis strains were characterized in this study. attb and attp sites conformed for the most part to the consensus sequence TATTTTT, although minor polymorphisms were noted. Prophages were integrated into similar sites in four strains, suggesting that these strains may have had a common ancestor. Two strains had three prophage copies each, and integration sites were identical. Two strains had two copies each. One of these shared two of the integration sites occupied in the three-copy strains, while the other shared one of these sites and harbored a second prophage in a unique site. Integration sites in the two strains with one prophage each were unique. Four MAV1 copies contained extensive substitutions within a region encoding a putative structural protein and the putative repressor protein. A 3-kb fragment was deleted from the right side of two of these copies. It is proposed that polymorphisms within MAV1 prophage integration sites and within the prophages themselves may help to identify phylogenetic relationships among virulent M. arthritidis strains.