Analysis of sequences flanking the vap regions of Dichelobacter nodosus: evidence for multiple integration events, a killer system, and a new genetic element

DNA sequences flanking the virulence-associated protein (vap) regions 1,2 and 3 were analysed using the Southern blotting and DNA sequencing. These vap regions of the Dichelobacter nodosus are found in 98% of virulent strains tested which suggest that they may have a role in virulence. They appear to have arisen by the integration of a genetic element into a tRNA gene. A new genetic element integrated into the Dichelobacter nodosus chromosome of vap region 3 was identified as either an integrated bacteriophage or conjugative transposon.