Combined Effects of Blood and Temperature Shift on Borrelia burgdorferi Gene Expression as Determined by Whole Genome DNA Array

Abstract

Borrelia burgdorferi undergoes differential gene expression during transmission from its tick vector to a vertebrate host. The addition of blood to a spirochete culture at 35°C for 48 h had a dramatic effect on gene expression of this organism. Utilizing B. burgdorferi whole genome DNA arrays, we compared the transcriptomes of the spirochetes following a 2-day temperature shift with blood and without blood. Using combined data from three independent RNA isolations we demonstrated that the addition of blood led to a differential expression of 154 genes. Of these, 75 genes were upregulated, with 49 (65%) of them encoded on plasmids. Blood supplementation of cultures also resulted in the downregulation of 79 genes, where 56 (70%) were plasmid encoded. We verified our results by reverse transcriptase PCR of several genes in both flat and feeding ticks. In the 2-day experiment we observed the effect that exposure to increased temperature and blood combined had on B. burgdorferi gene expression at this crucial time when the spirochetes begin to move from the vector to a new vertebrate host. These changes, among others, coincide with the upregulation of the chemotaxis and sensing regulons, of the lp38-encoded ABC transporter, of proteases capable of remodeling the outer surface of the spirochetes, and of the recombination genes of cp32 as a transient or initial part of the stress response of the phage. These are all functions that could cause or facilitate the changes that spirochetes undergo following a blood meal in the tick.

Live imaging reveals a biphasic mode of dissemination of Borrelia burgdorferi within ticks

“…Live imaging has revealed that this conception is an oversimplification. That Borrelia within unfed nymphal midguts are nonmotile is consistent with the quiescent metabolic state of organisms in this milieu (50)(51)(52)(53)(54) and is in line with observations made with crushed midguts dating back to the discovery of the Lyme spirochete as a tick-borne pathogen (49). On the other hand, our finding that the fed midgut is populated with replicating, but nonmotile, spirochetes was unexpected and runs counter to the prevailing notion, which equates metabolic activity with motility (58).…”

Borrelia burgdorferi Uniquely Regulates Its Motility Genes and Has an Intricate Flagellar Hook-Basal Body Structure

“…on April 7, 2019 by guest http://jb.asm.org/ conditions that mimic the mammalian or tick hosts (11,17,53,64). qRT-PCR confirmed that there is upregulation of some of these genes (M. Caimano and J. Radolf, personal communication).…”

IL-10 Deficiency Promotes Increased Borrelia burgdorferi Clearance Predominantly through Enhanced Innate Immune Responses

“…However, B. burgdorferi does specify Ն127 different putative lipoproteins, at least some of which are capable of promoting inflammatory responses (10,13,14). The lipoproteins expressed by B. burgdorferi are known to vary widely under the different environmental conditions they encounter during their natural infection cycle between arthropod and vertebrate hosts (15)(16)(17), but all of these proteins are predicted to possess similar triacyl modifications on their N-terminal cysteine residues (18). Studies from a number of laboratories have shown that these triacylated lipoproteins directly activate different host immune cells by signaling through TLR2 (19 -23) and the common intracellular adaptor molecule MyD88 (24,25).…”