PDF(Pubmed)
Abstract：
Anaplasma marginale is an obligate, intracellular, tick-borne bacterial pathogen that causes bovine anaplasmosis, an often severe, production-limiting disease of cattle found worldwide. Methods to control this disease are lacking, in large part due to major knowledge gaps in our understanding of the molecular underpinnings of basic host-pathogen interactions. For example, the surface proteins that serve as adhesins and, thus, likely play a role in pathogen entry into tick cells are largely unknown. To address this knowledge gap, we developed a phage display library and screened 66 A. marginale proteins for their ability to adhere to Dermacentor andersoni tick cells. From this screen, 17 candidate adhesins were identified, including OmpA and multiple members of the Msp1 family, including Msp1b, Mlp3, and Mlp4. We then measured the transcript of ompA and all members of the msp1 gene family through time, and determined that msp1b, mlp2, and mlp4 have increased transcript during tick cell infection, suggesting a possible role in host cell binding or entry. Finally, Msp1a, Msp1b, Mlp3, and OmpA were expressed as recombinant protein. When added to cultured tick cells prior to A. marginale infection, all proteins except the C-terminus of Msp1a reduced A. marginale entry by 2.2- to 4.7-fold. Except OmpA, these adhesins lack orthologs in related pathogens of humans and animals, including Anaplasma phagocytophilum and the Ehrlichia spp., thus limiting their utility in a universal tick transmission-blocking vaccine. However, this work greatly advances efforts toward developing methods to control bovine anaplasmosis and, thus, may help improve global food security.
摘要：
边缘无理虫是一种义务，细胞内，导致牛无形体病的蜱传细菌病原体，通常是严重的，全世界发现的限制生产的牛的疾病。缺乏控制这种疾病的方法，在很大程度上是由于我们对基本宿主-病原体相互作用的分子基础的理解的主要知识空白。例如,作为粘附素的表面蛋白质，因此，在病原体进入蜱细胞中可能起作用的原因在很大程度上是未知的。为了解决这个知识差距，我们开发了一个噬菌体展示文库，并筛选了66种A.marginale蛋白粘附于Dermacentorandersonitick细胞的能力。从这个屏幕,确定了17种候选粘附素，包括OmpA和Msp1家族的多个成员,包括Msp1b，Mlp3和Mlp4。然后我们通过时间测量ompA和msp1基因家族的所有成员的转录本，并确定msp1b，mlp2和mlp4在tick细胞感染期间转录本增加，提示在宿主细胞结合或进入中的可能作用。最后,Msp1a,Msp1b,Mlp3和OmpA表达为重组蛋白。当在边缘曲霉感染之前添加到培养的蜱细胞中时，除Msp1a的C末端外，所有蛋白质均可减少A.marginale进入2.2至4.7倍。除了OmpA,这些粘附素在人类和动物的相关病原体中缺乏直系同源物，包括吞噬体和埃里希菌。,从而限制了它们在通用蜱传播阻断疫苗中的应用。然而,这项工作极大地推进了开发控制牛无形体病的方法的努力，因此，可能有助于改善全球粮食安全。
