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 etiological agent of Lyme disease, persists in nature through an enzootic cycle consisting of a vertebrate host and an Ixodes tick vector. The sequence motifs modified by two well-characterized restriction/modification loci of B. burgdorferi type strain B31 were recently described, but the methylation profiles of other Lyme disease Borrelia have not been characterized. Herein, the methylomes of B. burgdorferi type strain B31 and 7 clonal derivatives, along with B. burgdorferi N40, B. burgdorferi 297, B. burgdorferi CA-11, B. afzelii PKo, B. afzelii BO23, and B. garinii PBr, were defined through PacBio SMRT sequencing. This analysis revealed 9 novel sequence motifs methylated by the plasmid-encoded restriction/modification enzymes of these Borrelia strains. Furthermore, while a previous analysis of B. burgdorferi B31 revealed an epigenetic impact of methylation on the global transcriptome, the current data contradict those findings; our analyses of wild-type B. burgdorferi B31 revealed no consistent differences in gene expression among isogenic derivatives lacking one or more restriction/modification enzyme(s).
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.
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.
Project description:The aim of the study was to compare the global transcriptional responses elicited in NHDF cells by three different strains of Borrelia burgdorferi ss (the agent of Lyme borreliosis), representative of different stages in the life cycle of Borrelia: one reference strain isolated from a tick (strain N40), and two invasive strains isolated from skin biopsy of erythema migrans (strain Pbre c4) and acrodermatitis chronica atrophians skin lesions (strain 1408 c1).
Project description:Borrelia burgdorferi, the tick-transmitted spirochete agent of Lyme disease, has a highly segmented genome with a linear chromosome and various linear or circular plasmids. Here, by imaging several chromosomal loci and 16 distinct plasmids, we show that B. burgdorferi is polyploid during growth in culture and that the number of genome copies decreases during stationary phase. B. burgdorferi is also polyploid inside fed ticks and chromosome copies are regularly spaced along the spirochete’s length in both growing cultures and ticks. This patterning involves the conserved DNA partitioning protein ParA whose localization is controlled by a potentially phage-derived protein, ParZ, instead of its usual partner ParB. ParZ binds its owe coding region and acts as a centromere-binding protein. While ParA works with ParZ, ParB controls the localization of the condensin, SMC. Together, the ParA/ParZ and ParB/SMC pairs ensure faithful chromosome inheritance. Our findings underscore the plasticity of cellular functions, even those as fundamental as chromosome segregation.
Project description:The alternative sigma factor RpoS plays a central role in the critical host-adaptive response of the Lyme disease spirochete, Borrelia burgdorferi. We previously identified bbd18 as a negative regulator of RpoS but could not inactivate bbd18 in wild-type spirochetes. In the current study we employed an inducible bbd18 gene to demonstrate the essential nature of BBD18 for viability of wild-type spirochete viability in vitro and at a unique point in vivo. Transcriptomic analyses of BBD18 depleted cells demonstrated global induction of RpoS-dependent genes prior to lysis, with the absolute requirement for BBD18, both in vitro and in vivo, circumvented by deletion of rpoS. The increased expression of plasmid prophage genes and the presence of phage particles in the supernatants of lysing cultures indicate that RpoS regulates phage lysis-lysogeny decisions. Through this work we identify a mechanistic link between endogenous transducing prophages and the RpoS-dependent adaptive response of the Lyme disease spirochete. The alternative sigma factor RpoS plays a central role in the critical host-adaptive response of the Lyme disease spirochete, Borrelia burgdorferi. We previously identified bbd18 as a negative regulator of RpoS but could not inactivate bbd18 in wild-type spirochetes. In the current study we employed an inducible bbd18 gene to demonstrate the essential nature of BBD18 for viability of wild-type spirochete viability in vitro and at a unique point in vivo. Transcriptomic analyses of BBD18 depleted cells demonstrated global induction of RpoS-dependent genes prior to lysis, with the absolute requirement for BBD18, both in vitro and in vivo, circumvented by deletion of rpoS. The increased expression of plasmid prophage genes and the presence of phage particles in the supernatants of lysing cultures indicate that RpoS regulates phage lysis-lysogeny decisions. Through this work we identify a mechanistic link between endogenous transducing prophages and the RpoS-dependent adaptive response of the Lyme disease spirochete.
Project description:The aim of the study was to compare the global transcriptional responses elicited in NHDF cells by three different strains of Borrelia burgdorferi ss (the agent of Lyme borreliosis), representative of different stages in the life cycle of Borrelia: one reference strain isolated from a tick (strain N40), and two invasive strains isolated from skin biopsy of erythema migrans (strain Pbre c4) and acrodermatitis chronica atrophians skin lesions (strain 1408 c1). Three different experimental conditions have been tested: (1) unstimulated NHDF vs NHDF stimulated by Borrelia strain N40 / (2) unstimulated NHDF vs NHDF stimulated by Borrelia strain Pbre c4 / (3)M-BM- unstimulated NHDF vs NHDF stimulated by Borrelia strain 1408 c1. There is 2 biological replicates for each condition. All NHDF stimulation have been performed in independent experiments.
Project description:Transcriptional profiling of gene expression between parental strain B31 and rrp1 mutant. Cyclic-di-GMP is a bacterial second messenger that modulates many biological processes. Although its role in bacterial pathogenesis during mammalian infection has been widely recognized, the role of c-di-GMP in pathogen's life cycle in vector hosts is less understood. The enzootic cycle of the Lyme disease pathogen Borrelia burgdorferi involves both a mammalian host and an Ixodes tick vector. The B. burgdorferi genome encodes a single copy of the diguanylate cyclase gene (rrp1), which is responsible for the production of c-di-GMP. To determine the role of c-di-GMP in the life cycle of B. burgdorferi, an Rrp1-deficient B. burgdorferi strain was generated. The rrp1 mutant remains infectious in the mammalian host, but could not survive in the tick vector. To identify the mechanisms of Rrp1 contributing to B. burgdorferi pathogenesis and gene regulation, microarray was employed to compare gene expression profiles between the parental strain B31 and the rrp1 mutant. Two-condition experiment, B31 vs. rrp1 mutant. Biological replicates: 3 B31, 3 rrp1 mutant, independently grown and harvested. One replicate (dye-swap) per array.
Project description:Lyme borreliosis (LB) is a tick-borne infection caused by Borrelia burgdorferi. Dogs are at high risk of exposure to ticks and tick-borne pathogens, including B. burgdorferi. Immunodiagnostic assays are usually based on whole-cell preparations of B. burgdorferi as substrate and, consequently, interpretation of results is confounded by antibody cross-reactivity between borrelial antigens and other bacterial species, as well as the anti-LB vaccination status of the dog. For this study, we examined sera from 33 dogs that were experimentally infected with B. burgdorferi through tick bite. These sera were compared with sera from uninfected dogs in their reactivities to 72 different recombinant B. burgdorferi antigens and 24 OspC protein types on a protein microarray. Amongst antigens frequently recognized by infected dogs were several known to be immunogens for humans, such as Decorin-binding protein A (BBA25), BBA64, fibronectin-binding protein (BBK32), VlsE, Erp and Bdr, CRASP proteins, OspC proteins and some flagellar antigens. Of special interest were the novel antigens BBB14 and BB0844, both hypothetical lipoproteins about which very little is currently known, and that were frequently and strongly recognized by infected dog sera. The antibody response of B. burgdorferi-infected dogs presents both similarities and differences from human counterparts, and both can be important for improvement of canine LB diagnosis and vaccine development. Antibody profiling was performed on sera from dogs experimentally-infected with B. burgdorferi and unexposed controls against antigens of B. burgdorferi. Thirty-three serum samples from experimental infections, and 5 unexposed controls were probed on a protein microarray displaying 24 OspC proteins of B. burgdorferi .