Mutational Analysis of Putative Regulatory Elements of the Antigenically Variable VlsE Protein of the Lyme Disease Spirochete
Abstract
Borrelia burgdorferi is the causative agent of Lyme disease, the most prevalent tick-borne disease in the United States. This bacterial pathogen is capable of long-term infection of humans that can lead to severe arthritis and neurological complications. The ability of the Lyme disease bacteria to persistently infect is due to an immune evasion process called antigenic variation. This genetic system causes changes in the VlsE protein of B. burgdorferi that allows the bacterium to stay one step ahead of the host antibody response. VlsE expression and antigenic variation are known to be highly regulated processes, but the mechanistic aspects behind this regulation are still unknown. Once the key regulatory elements and important mechanistic components are defined, they will provide critical clues to the proteins involved in vlsE expression and recombination. In turn, this will provide the means to develop therapeutics to target these proteins and prevent persistent infection by the Lyme disease pathogen. Since its discovery two decades ago, the vlsE genetic system has not been receptive to mutational analysis by any available methods. This fact has created the need for the development of a system that is amenable to genetic manipulation. Recently, our lab has generated a specialized DNA construct with high potential to meet this demand. The strategies described herein are innovative for two main reasons: (1) they entail genetic manipulation of the vlsE system using a unique DNA construct, and (2) they involve the transmission of DNA directly into the bacterium. The objective of our proposed studies will be to identify the mechanistic determinants required for vlsE regulated expression and recombination. To do this, we will set out to pursue the following two specific aims: (1) Identify the genetic determinants required for vlsE regulated expression, and (2) Determine the effects of vlsE expression on VlsE antigenic variation. When applied, the results expected from this study will lead to strategies that will ultimately allow targeting of this system to significantly reduce the pathogen s ability to establish a persistent host infection. The proposed study is relevant to the "mechanisms of persistence of Lyme disease" in the Pathogenesis focus area due to the fact that expression and antigenic variation of VlsE are critical for persistent infection. Moreover, the development of our novel plasmid will provide a unique tool to study persistence and thus will deal with the area of "new research tools to support studies of pathogenesis." Finally, we have previously published data demonstrating the critical importance of VlsE antigenic variation for the natural life cycle of the Lyme disease pathogen and, therefore, the proposed work is also associated with "interrupting the cycle of disease agents in nature." Combined, the proposed study has the potential to address multiple focus areas intended for this award mechanism of the FY17 TBDRP. Thus, the proposed research is relevant to that part of the Defense Health Agency s mission that pertains to developing fundamental knowledge that will help to reduce the burdens of human illness and disability to benefit military Service members and the American public. The potential benefits will not only apply to individuals with active Lyme disease infections, but also have the capacity to prevent persistent infections.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1810192
Entities
People
- Troy Bankhead
Organizations
- United States Army
- Washington State University