关键词: 伯氏疏螺旋体, 硬蜱属, 哺乳类宿主, 分子相互作用

Abstract: Lyme borreliosis is a prevalent arthropod-borne disease caused by the spirochete, Borrelia burgdorferi. The microbe consists in nature through an intricate tick-mammal cycle. B.burgdorferi is transmitted to vertebrates via ticks belonging to the Ixodes ricinus complex. Over the last two decades, scientists have been trying to unravel the complex mechanisms by which B.burgdorferi maintained in a unique enzootic cycle. Our special attention has been paid to addressing the molecular interaction strategies that B.burgdorferi employs for effective colonization, migration and transmission through ticks. Studies have shown that B.burgdorferi expresses a select set of genes in distinct phases of its life cycle- and in specific tissue locations. The outer surface protein (Osp) A of B.burgdorferi is down-regulated within a mammalian host, turned on as soon as the spirochete enters and resides in the arthropod vector. OspA acts as an adhesion, which binds a receptor in the tick midgut, and OspA is required for spirochetes to successfully colonize in the tick midgut. B.burgdorferi lacking OspA cannot survive in the tick. To further understand the mechanism of OspA-based adherence, we have recently identified and characterized the tick receptor for OspA, named TROSPA. TROSPA predominantly localized in the tick midgut, specifically bound to ospA expressing B.burgdorferi and TROSPA knockdown ticks allowed poor attachment of spirochetes in the tick midgut. These observations clearly indicate that like OspA, TROSPA is also actively engaged in the colonization of spirochetes in Ixodes ticks. The OspA-TROSPA interaction is the first illustration of a molecular interface where both microbial as well as vector gene products equally contribute to B.burgdorferi survival in nature. We also find that there are the complex pathogen-vector-mammalian host triangle interactions during mammalian infection tith B.burgdorferi. Ixodes tick salivary protein Salp15 help spirochetes to infect the mice. B.burgdorferi basic memrane protein A gene(bmpA) andbmpB facilitate spirochetes to disseminate to and locate in joint tissue and induce arthritis. All these findings provide deep insights into transmission and pathogenesis of B.burgdorferi.