Project description:To determine whether the influences of Ixodes scapularis protein disulfide isomerase A6 (IsPDIA6) on Borrelia burgdorferi colonization is the result of physiological responses, we performed RNA-sequencing (RNA-seq) to compare the transcriptomes of control (GFP) and IsPDIA6-silenced ticks.
Project description:Adiponectin-mediated pathways contribute to mammalian homeostasis; however, little is known about adiponectin and adiponectin receptor signaling in arthropods. In this study, we demonstrate that Ixodes scapularis ticks have an adiponectin receptor-like protein (ISARL) but lack adiponectin, suggesting activation by alternative pathways. ISARL expression is significantly upregulated in the tick gut after Borrelia burgdorferi infection, suggesting that ISARL signaling may be co-opted by the Lyme disease agent. Consistent with this, RNA interference (RNAi)-mediated silencing of ISARL significantly reduced the B. burgdorferi burden in the tick. RNA-seq-based transcriptomics and RNAi assays demonstrate that ISARL-mediated phospholipid metabolism by phosphatidylserine synthase I is associated with B. burgdorferi survival. Furthermore, the tick complement C1q-like protein 3 interacts with ISARL, and B. burgdorferi facilitates this process. This study identifies a new tick metabolic pathway that is connected to the life cycle of the Lyme disease spirochete.
Project description:Borrelia burgdorferi, the causative agent of Lyme disease, is transmitted to vertebrate hosts by Ixodes ticks. As it moves from tick to host, B. burgdorferi must adapt to survive in a vastly different environment. During the tick bloodmeal, which lasts several days, B. burgdorferi is primed for mammalian infection, growing increasingly virulent as it senses cues from its surroundings in the tick. This conditioning is dependent on key transcriptional regulators; however, the downstream transcriptional changes occurring inside of the tick that promote B. burgdorferi transmission and infection are poorly understood due to technical difficulties in sequencing the B. burgdorferi transcriptome from inside of ticks. We developed a protocol to enrich and sequence B. burgdorferi from inside the tick, and we measured global transcriptional changes occurring in feeding ticks. We identified 192 genes that change expression twofold over the course of the tick bloodmeal, which were predominantly located on the plasmids of the genome. The majority of the upregulated genes encode proteins found at the cell envelope or proteins of unknown function, including 45 upregulated genes encoding outer surface lipoproteins. These genes that increase during feeding are candidates for future functional studies, which can help identify new targets for methods that aim to control the spread of Lyme disease.
