PCR-based plasmid profiling to compare the plasmid contents of the strains employed in this study. PCR amplification with primers specific for each of the known endogenous B. burgdorferi plasmids was used to compare the plasmid content of parent Bb297, BbKH500, and BbKH501. Sequence information for the primers utilized is provided in Table 4. Plasmid designations above each lane are based on strain B31 plasmid annotation. DNA size standards (M) are shown in base pairs.