Borrelia burgdorferi Interactions with Mammalian Host Cells

描述（由申请方提供）：莱姆病由螺旋体细菌伯氏疏螺旋体引起，是美国最常见的节肢动物传播感染，由于报告病例数量显著增加，已被归类为重新出现的媒介传播感染。莱姆病是一个重要的公共卫生问题，特别是在地方病流行的国家，它有助于显着的发病率。B的能力。在哺乳动物中引起感染的伯氏螺旋体依赖于其响应于其在通过蜱叮咬传播时遇到的高度不同的环境信号而快速改变基因表达的能力。几项全基因组转录分析，比较B。在模拟蜱载体或哺乳动物宿主的条件下培养的burgdorferi，揭示了线性质粒54（Ip54）上的几个质粒编码基因在哺乳动物宿主特异性条件下被上调。基于序列的二级结构分析的几个这些差异表达的ORF显示，BBA 34有一个甘氨酸-甘氨酸-谷氨酸（RGD）基序在N-末端区域，这个基序可能是表面暴露。此外，基于序列相似性，BBA 34是寡肽通透酶A（OppA 5）蛋白的直向同源物，但不像其他染色体编码的OppA直向同源物那样结合七肽，并且在B中上调。在传播到哺乳动物宿主时的伯氏螺旋体。 本提案的目的是确定BBA 34上的RGD基序是否会促进与哺乳动物细胞的相互作用，推测是通过与整合素的直接相互作用。第一个具体的目的是确定重组BBA 34蛋白与各种整合素的相互作用，无论是纯化的或表达的哺乳动物细胞。我们将使用全长、N-末端和C-末端重组BBA 34蛋白来确定RGD基序在与各种整合素结合中的作用。第二个具体目的是确定B的bba 34突变体的结合、感染性和组织传播特性。在莱姆病的鼠模型中的burgdorferi。第三个具体目的是表征B的bba 34-/bbk 32-和bba 34-/p66-双突变体的结合和感染性。在莱姆病的鼠模型中的burgdorferi。我们将确定多个疏螺旋体决定簇的丢失对宿主细胞粘附的重要性。这些研究将有助于确定宿主-病原体相互作用，这对B在哺乳动物宿主中的定殖至关重要。burgdorferi。

DESCRIPTION (provided by applicant): Lyme disease, caused by the spirochetal bacterium Borrelia burgdorferi, is the most prevalent arthropod-borne infection in the United States and has been classified as a re-emerging vector-borne infection due to a significant increase in the number of reported cases. Lyme disease is an important public health issue, particularly in endemic states where it contributes to significant rates of morbidity. The ability of B. burgdorferi to cause infection in mammals is dependent on its ability to alter gene expression rapidly in response to highly disparate environmental signals that it encounters upon transmission through a tick bite. Several genome-wide transcriptional analyses, comparing B. burgdorferi cultivated under conditions that mimic the tick vector or the mammalian host, revealed that several plasmid encoded genes on linear plasmid 54 (Ip54) are up-regulated under mammalian host-specific conditions. Sequence based secondary structure analysis of several of these differentially expressed ORFs revealed that BBA34 has an arginine-glycine-glutamic acid (RGD) motif at the N-terminal region and that this motif is probably surface-exposed. Moreover, based on sequence similarity, BBA34 is an orthologue of oligopeptide permease A (OppA5) protein but does not bind heptapeptides like other chromosomally encoded OppA orthologues and is up-regulated in B. burgdorferi upon transmission to mammalian host. The objective of this proposal is to determine if the RGD motif on BBA34 will facilitate interactions with mammalian cells presumably through direct interactions with integrins. The first specific aim is to determine the interactions of recombinant BBA34 proteins with various integrins either purified or expressed on mammalian cells. We will determine the role of RGD motif in binding to various integrins using full-length, N-terminal and C-terminal recombinant BBA34 proteins. The second specific aim is to determine the binding, infectivity and tissue dissemination characteristics of a bba34- mutant of B. burgdorferi in the murine model of Lyme disease. The third specific aim is to characterize the binding and infectivity of bba34-/bbk32- and bba34-/p66- double mutants of B. burgdorferi in the murine model of Lyme disease. We will determine the significance of the loss of multiple borrelial determinants on host-cell adherence. These studies will help to determine the host-pathogen interactions that are critical for the colonization of the mammalian host by B. burgdorferi.