Role of<i>Borrelia burgdorferi</i>Linear Plasmid 25 in Infection of<i>Ixodes scapularis</i>Ticks

Strother, Keith O.; Silva, Aravinda M. de

doi:10.1128/jb.187.16.5776-5781.2005

Cited by 41 publications

(50 citation statements)

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“…The shuttle vector pBSV2, also kindly provided by Patricia Rosa, is derived from B. burgdorferi B31 cp9 and contains a kanamycin resistance cassette. The first modification of the shuttle vector was created by inserting the gene BBE22 into the vector to create the vector pBSV2ϩ22 as outlined by Strother and de Silva (24). The second modified shuttle vector was created by insertion of the B31-C1 ospAB gene connected to the B31-C1 flaB promoter into the pBSV2ϩ22 shuttle vector to create pBSV2ϩ22ϩFA (Fig.…”

Section: Methodsmentioning

confidence: 99%

Infection of Mice with Lyme Disease Spirochetes Constitutively Producing Outer Surface Proteins A and B

et al. 2007

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Outer surface protein A (OspA) of the Lyme disease spirochete is primarily produced in the tick vector. OspA, which is a receptor for attaching spirochetes to the tick gut, is down regulated as the spirochetes leave the tick and enter the mammalian host. Although OspA is not a major antigen produced in the mammal, the protein appears to be produced under some conditions and production has been linked to more severe disease. A Lyme disease vaccine based on recombinant OspA has been approved for human use. However, the vaccine is no longer available, in part because of fears that OspA causes arthritis in people. To further understand the consequences of OspA production in the host, we created a Borrelia burgdorferi mutant that was unable to down regulate OspA. C3H/HeN mice infected with this mutant developed a specific anti-OspA immune response, and the spirochetes were unable to persist in these mice. In contrast, immunodeficient SCID mice were persistently infected with the mutant. We conclude that spirochetes producing OspA and B from the flaB promoter in immunocompetent mice stimulate an immune response that clear the bacteria without any signs of disease development in the mice.The Lyme disease spirochete Borrelia burgdorferi produces an array of outer surface lipoproteins (Osps). While some of the lipoproteins are chromosomally produced, the majority are produced on extrachromosomal plasmids. As many as 91, or 14.5%, of the genes encoded on plasmids are putative lipoproteins (7). Many plasmid-encoded lipoproteins are differentially expressed in the tick vector or the vertebrate host, indicating that they function at specific stages in the life cycle of the spirochete. The function of several lipoproteins has been studied using genetic and biochemical approaches, but there still remains much to be learned about these proteins.OspA and B are two proteins encoded by a single operon on linear plasmid 54 (lp54). These two surface proteins are produced in abundance by spirochetes grown in culture. OspA, in particular, has been the focus of study because the gene encoding OspA was among the first B. burgdorferi genes to be cloned and a recombinant OspA vaccine has been approved for use in people and animals. However, the vaccine is no longer available, in part because of fears that the protein or an immune response against the protein could induce arthritis. OspA is differentially produced during the natural transmission cycle of the spirochete. When spirochetes first enter a tick, OspA is upregulated and the protein is required for tick colonization. OspA serves as a ligand for tethering spirochetes to a receptor in the tick gut (20). When infected ticks feed again, the spirochetes multiply within the vector, downregulate the production of OspA and infect the host via the salivary glands of the tick. Nonspecific natural antibody in a host may be one signal that down regulates ospA expression (16). Mutants missing OspA and B are able to infect mice and cause disease (28).There is conflicting data about the role of ...

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Section: Methodsmentioning

confidence: 99%

Infection of Mice with Lyme Disease Spirochetes Constitutively Producing Outer Surface Proteins A and B

et al. 2007

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“…The plasmids of B. burgdorferi are present at unit copy number relative to the chromosome (22), and some are relatively unstable during in vitro propagation (52,57). The loss of linear plasmids lp25, lp28-1, and lp36 by strain B31 was found to correlate with the loss of infectivity in mice (20,31,45,56), leading to the identification of genes carried on these plasmids that are dispensable in vitro but required in vivo during an experimental infectious cycle (21,26,35,44,47). The loss of two linear plasmids, lp25 and lp56, was shown to correlate with enhanced shuttle vector transformation, suggesting that specific lp25 and lp56 gene products present a barrier to stable introduction of foreign DNA (34).…”

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Defining the Plasmid-Borne Restriction-Modification Systems of the Lyme Disease SpirocheteBorrelia burgdorferi

2011

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The restriction-modification (R-M) systems of many bacteria present a barrier to the stable introduction of foreign DNA. The Lyme disease spirochete Borrelia burgdorferi has two plasmid-borne putative R-M genes, bbe02 and bbq67, whose presence limits transformation by shuttle vector DNA from Escherichia coli. We show that both the bbe02 and bbq67 loci in recipient B. burgdorferi limit transformation with shuttle vector DNA from E. coli, irrespective of its dam, dcm, or hsd methylation status. However, plasmid DNA purified from B. burgdorferi transformed naïve B. burgdorferi much more efficiently than plasmid DNA from E. coli, particularly when the bbe02 and bbq67 genotypes of the B. burgdorferi DNA source matched those of the recipient. We detected adenine methylation of plasmid DNA prepared from B. burgdorferi that carried bbe02 and bbq67. These results indicate that the bbe02 and bbq67 loci of B. burgdorferi encode distinct R-M enzymes that methylate endogenous DNA and cleave foreign DNA lacking the same sequence-specific modification. Our findings have basic implications for horizontal gene transfer among B. burgdorferi strains with distinct plasmid contents. Further characterization and identification of the nucleotide sequences recognized by BBE02 and BBQ67 will facilitate efficient genetic manipulation of this pathogenic spirochete.Borrelia burgdorferi sensu lato is a zoonotic pathogen whose natural infectious cycle alternates between a tick vector and rodent or bird reservoir hosts (1,7,8,14,32,33,36). Transmission of B. burgdorferi to humans occurs through the bite of an infected tick and can lead to Lyme disease, which is a major public health concern in areas of North America and Europe where B. burgdorferi is endemic (8, 53).The genomic structure of the spirochete B. burgdorferi is unique, consisting of a linear chromosome of approximately 900 kb and more than 20 linear (lp) and circular (cp) plasmids, ranging in size from ϳ5 kb to 56 kb, in the type strain B31 (9,10,11,19,42). The plasmids of B. burgdorferi are present at unit copy number relative to the chromosome (22), and some are relatively unstable during in vitro propagation (52, 57). The loss of linear plasmids lp25, lp28-1, and lp36 by strain B31 was found to correlate with the loss of infectivity in mice (20,31,45,56), leading to the identification of genes carried on these plasmids that are dispensable in vitro but required in vivo during an experimental infectious cycle (21,26,35,44,47). The loss of two linear plasmids, lp25 and lp56, was shown to correlate with enhanced shuttle vector transformation, suggesting that specific lp25 and lp56 gene products present a barrier to stable introduction of foreign DNA (34). Further studies linked the transformation phenotype of B. burgdorferi strain B31 with the bbe02 and bbq67 genes on lp25 and lp56, respectively, and the putative restriction-modification (R-M) enzymes that they encode (11,27,29,34). The recent demonstration by Chen and colleagues of enhanced transformation of B. burgdorferi follow...

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“…IMMUN. (52,64,65). Nonetheless, generation of mts using this approach facilitated analysis of the effect of loss of one or more genes in the infectivity of B. burgdorferi for the mammalian host.…”

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Role of the BBA64 Locus of Borrelia burgdorferi in Early Stages of Infectivity in a Murine Model of Lyme Disease

et al. 2008

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Borrelia burgdorferi, the causative agent of Lyme disease, undergoes rapid adaptive gene expression in response to environmental signals encountered during different stages of its life cycle in the arthropod vector or the mammalian host. Among all the plasmid-encoded genes of B. burgdorferi, several linear plasmid 54 (lp54)-encoded open reading frames (ORFs) exhibit the greatest differential expression in response to mammalian host-specific temperature, pH, and other uncharacterized signals. These ORFs include members of the paralogous gene family 54 (pgf 54), such as BBA64, BBA65, and BBA66, present on lp54. In an attempt to correlate transcriptional up-regulation of these pgf 54 members to their role in infectivity, we inactivated BBA64 and characterized the phenotype of this mutant both in vitro and in vivo. There were no major differences in the protein profiles between the BBA64 mutant and the control strains, while immunoblot analysis indicated that inactivation of BBA64 resulted in increased levels of BBA65. Moreover, there was no significant difference in the ability of the BBA64 mutant to infect C3H/HeN mice compared to that of its parental or complemented control strains as determined by culturing of viable spirochetes from infected tissues. However, enumeration of spirochetes using quantitative real-time PCR revealed tissue-specific differences, suggesting a minimal role for BBA64 in the survival of B. burgdorferi in select tissues. Infectivity analysis of the BBA64 mutant suggests that B. burgdorferi may utilize multiple determinants to establish infection in mammalian hosts.Lyme disease is the most prevalent arthropod-borne infection in the United States and remains a significant public health issue in certain geographic loci (3,46). It is a multiphasic disorder with clinical symptoms involving the cutaneous, musculoskeletal, cardiovascular, and nervous systems (62). Borrelia burgdorferi, the causative agent of Lyme disease, is transmitted to several vertebrate hosts, including humans, by the bite of infected Ixodes ticks. When ticks consume a blood meal from mammalian hosts, there is a rapid alteration of gene expression in B. burgdorferi, facilitating adaptation of the spirochetes to the highly disparate environmental conditions that exist between the tick vector and the vertebrate host (4, 9, 10, 15, 29, 30-32, 44, 53, 57-59, 63, 67). This adaptive gene expression may aid in the efficient trafficking of the spirochetes from the tick vector to the mammalian host and subsequently facilitate dissemination and colonization of various host tissues (16,22).Whole-genome transcriptional analyses using B. burgdorferi, propagated under in vitro growth conditions that mimic either the tick vector or mammalian host environment, have revealed preferential expression of plasmid-encoded genes (4,44,53,66). Among the several linear and circular plasmids present in B. burgdorferi, linear plasmid 54 (lp54) encodes the largest number of open reading frames (ORFs) that exhibit differential gene expression in respon...

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Role ofBorrelia burgdorferiLinear Plasmid 25 in Infection ofIxodes scapularisTicks

Cited by 41 publications

References 30 publications

Infection of Mice with Lyme Disease Spirochetes Constitutively Producing Outer Surface Proteins A and B

Infection of Mice with Lyme Disease Spirochetes Constitutively Producing Outer Surface Proteins A and B

Defining the Plasmid-Borne Restriction-Modification Systems of the Lyme Disease SpirocheteBorrelia burgdorferi

Role of the BBA64 Locus of Borrelia burgdorferi in Early Stages of Infectivity in a Murine Model of Lyme Disease

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