Longitudinal map of transcriptome changes in the Lyme pathogenBorrelia burgdorferiduring tick-borne transmission

Borrelia burgdorferi(Bb), the causative agent of Lyme disease, adapts to vastly different environments as it cycles between tick vector and vertebrate host. During a tick bloodmeal,Bbalters its gene expression to prepare for vertebrate infection; however, the full range of transcriptional changes that occur over several days inside of the tick are technically challenging to capture. We developed an experimental approach to enrichBbcells to longitudinally define their global transcriptomic landscape inside nymphalIxodes scapularisticks during a transmitting bloodmeal. We identified 192Bbgenes that substantially change expression over the course of the bloodmeal from one to four days after host attachment. The majority of upregulated genes encode proteins found at the cell envelope or proteins of unknown function, including 45 outer surface lipoproteins embedded in the unusual protein-rich coat ofBb. As these proteins may facilitateBbinteractions with the host, we utilized mass spectrometry to identify candidate tick proteins that physically associate withBb. TheBbenrichment methodology along with theex vivo Bbtranscriptomes and candidate tick interacting proteins presented here provide a resource to facilitate investigations into key determinants ofBbpriming and transmission during the tick stage of its unique transmission cycle.