We are also inactivating these genes in order to test whether mutants can undergo temperature-induced expression of osp genes in vitro and completion of the infectious cycle in vivo . Develop tools with which to genetically manipulate Bb. Studies in the biology of Bb and pathogenesis of Lyme disease are severely limited by the lack of genetic tools. We have used this method to inactivate four genes on a circular Bb plasmid. Each of these genes encodes a protein that is potentially important in the transmission or adaptation of Bb between ticks and mammals.
Future plans are to test the effects of mutated genes in a natural mouse-tick transmission cycle.
We have an ongoing effort to develop additional and better genetic tools in Bb, including additional selectable markers. Develop an understanding of Bb genome structure, function, and replication. Bb has an unusual genome composed of a linear chromosome and multiple linear and circular plasmids, many of which carry the genes for important Lyme disease antigens. We are studying several of these plasmids with the goal of understanding the roles of these DNAs and their encoded proteins in the life cycle of Bb and the transmission of Lyme disease. We have demonstrated the presence of single copy genes encoding essential purine biosynthetic enzymes on a circular plasmid.