Directed insertion of a selectable marker into a circular plasmid of Borrelia burgdorferi

Targeted insertion of the antibiotic resistance marker gyrB(super r) into a 26-kb circular plasmid (cp26) is described. It is the first example of a directed mutation in Borrelia burgdorferi, whereby a large segment of heterologous DNA has been inserted via homologous recombination with flanking sequences. The process confirms the feasibility of specific gene inactivation by allelic exchange.