Summary
The ability of Borrelia burgdorferi to cause Lyme disease is highly dependent on its capacity to establish a
successful infection upon entering the mammalian host. Moreover, survival of the Lyme disease pathogen in
nature is completely dependent on its enzootic life cycle involving both a tick vector and reservoir host. The
transition between these two very different environments requires the ability to rapidly adapt through changes
in gene expression. Recent studies in our lab have provided evidence that the functional product of the bbd07
intergenic region of lp17 acts as a small non-coding RNA (sRNA) important for host adaptation. Despite this
advance, there remains a fundamental gap in our understanding of the mechanistic aspects of bbd07-mediated
gene regulation, and the genes subjected to its regulatory effects are unknown. Our long-term goals are to
identify and characterize factors necessary for B. burgdorferi adaptation to the tick and mammalian host
environments. The overall objective of this application is to establish the importance of bbd07 for regulation of
genes important for host colonization by B. burgdorferi. Based on preliminary data, the central hypothesis of
this proposal is that bbd07 acts as a sRNA essential for regulation of genes known to be important for host
adaptation. The rationale for the proposed research is that bbd07 RNA and the gene products under its
regulatory influence represent potential targets for the development of therapeutics against human infection by
the pathogen, as well as disruption of its enzootic life cycle. Thus, the proposed research is relevant to that
part of NIH’s mission that pertains to developing fundamental knowledge that will potentially help to reduce the
burdens of human illness and disability. Guided by published and preliminary data, our hypothesis will be
tested by pursuing the following two specific aims: 1) Determine the regulatory mechanism of bbd07 and
identity of additional target genes, and 2) Establish a correlation between bbd07 expression and ospC
repression during host infection. Under the first aim, the 5’ end of bbd07 RNA will be characterized by RACE,
sRNA-mRNA target interactions will be mapped, and iTRAQ analysis will be used to determine the large-scale
effects of bbd07 deletion on the B. burgdorferi proteome. Under the second aim, the relative levels of bbd07
and ospC expression in the murine and ticks hosts will be quantified, and OspC production visualized using an
immunofluorescence assay. The proposed work is innovative because it utilizes a novel RNA-seq-based
method to globally map sRNA-mRNA target interactions in B. burgdorferi, and is the first mutational analysis of
bbd07 to assess its respective importance for regulation of genes involved in host adaptation. When applied,
the knowledge gained from the proposed studies has the potential to elucidate new drug targets to treat and
prevent Lyme disease.