mRNA decay in Borrelia burgdorferi under conditions of osmotic stress

The bacterium Borrelia burgdorferi is a spirochete that cycles between tick and vertebrate hosts, infecting them with Lyme disease. Gene expression is regulated in B. burgdorferi as a response to changes in environmental stimuli that occur as the bacterium changes hosts. In particular, certain virulence factors that are regulated by the RpoN-RpoS pathway, specifically dbpA, ospC, and ospA are known to be essential to the transmission and acquisition of B. burgdorferi. The importance of gene regulation of these key virulence factors in the enzootic cycle is well established; however mRNA degradation pathways are not well characterized in B. burgdorferi. In this study, mRNA decay in B. burgdorferi was investigated by arresting transcription using the antibiotic Actinomycin D. In cells cultured in environments of different osmolarities mimicking both the tick vector and vertebrate host, the time-dependent decay of the mRNA transcripts encoding for specific virulence factors was studied using qRT-PCR. Preliminary results suggest that the mRNA transcripts encoding for these key virulence factors may be differentially degraded in different osmotic environments. These results are consistent with previous findings on protein expression levels and give a preliminary characterization of mRNA decay and gene regulation in B. burgdorferi.