A second allele of eppA in Borrelia burdorferi strain B31 is located on the previously undetected circular plasmid cp9-2

Although sequence analysis of Borrelia burgdorferi isolate B31 was recently declared "complete," we found that cultures of this strain can contain a n ovel 9-kb circular plasmid, cp9-2. The newly described plasmid contains bot h sequence similarities with and differences from the previously identified B31 plasmid cp9-1 (formerly cp9). cp9-1 and cp9-2 each encode a unique all ele of EppA, a putative membrane protein synthesized by B. burgdorferi duri ng mammalian infection.