A novel zebrafish embryo model to define virulence factors of Bartonella henselae

描述（由申请方提供）：人畜共患细菌汉赛巴尔通体（Bh）感染可导致一系列临床症状和疾病，包括与猫抓病中观察到的局部Bh感染相关的淋巴结病，以及由全身性疾病引起的心内膜炎和菌血症。在一些患者中，Bh的全身感染包括杆菌性血管瘤病，其特征在于由于小血管增殖而导致的皮肤或内脏器官上的红色/紫色结节。这种不寻常的血管生成宿主对感染的反应在某些巴尔通体属的细菌中是独特的。体外研究已经确定了重要的毒力因子在建立感染和/或引发宿主反应中发挥作用。第一个是VirB/VirD 4 IV型分泌系统，其负责递送以不同能力作用于内皮细胞的巴尔通体效应蛋白（Beps A-G）。第二个主要毒力因子是VirB非依赖性第二IV型分泌系统Trw，其编码多种蛋白质，包括小粘附素TrwL 1-TrwL-8，其已显示在宿主细胞粘附中起重要作用。最后，高分子量三聚体自身转运蛋白粘附素BadA已在体外被广泛研究，并且对于自身凝集、粘附于宿主细胞、结合于细胞外基质蛋白、抑制吞噬作用和诱导血管生成至关重要。虽然在体外研究已被证明是宝贵的Bh发病机制的研究，没有Bh毒力因子已被证实在体内和非常少的是知道如何编码这些毒力因子的基因进行调节。为了解决这个问题，我们已经开发了一种新的体内模型，Bh感染转基因斑马鱼（ZF）胚胎，使我们能够监测感染和宿主反应，包括血管生成。我们假设，我们的ZF胚胎模型将使我们能够：更严格地测试的作用，已在体外定义的毒力因子，确定新的毒力因子和监管机构的毒力在体内，并评估这些基因产物的作用，在宿主对Bh感染的反应。为了验证这些假设，我们提出了以下具体目标：1）确定毒力因子和毒力调节因子在Bh感染中的作用， 转基因ZF胚胎模型，和2）确定Bh毒力因子和调节蛋白在实验感染的转基因ZF胚胎中引发宿主对感染的应答中的作用。迫切需要一种体内模型来更好地了解这种细菌的独特发病机制和宿主反应，以开发新的治疗策略。

DESCRIPTION (provided by applicant): Infection of humans with the zoonotic bacterium Bartonella henselae (Bh) can result in a range of clinical symptoms and disease including lymphadenopathy associated with localized Bh infection observed in cat-scratch disease, to endocarditis and bacteremia resulting from systemic disease. In some patients, systemic infection with Bh includes bacillary angiomatosis which is characterized by red/purple nodules on the skin or internal organs due to proliferation of the small blood vessels. This unusual angiogenic host response to infection is unique among bacteria to certain Bartonella species. In vitro studies have defined important virulence factors in Bh that play a role in establishing infection and/or eliciting a host response. The first is the VirB/VirD4 type IV secretion system that is responsible for delivering the bartonella effector proteins (Beps A-G) that act on endothelial cells in varying capacities. The second major virulence factor is a VirB-independent second type IV secretion system Trw, which encodes multiple proteins including small adhesins TrwL1-TrwL-8 which have been shown to play an important role in host cell adherence. Lastly, the high molecular weight trimeric auto transporter adhesin BadA has been studied extensively in vitro and is critical for auto agglutination, adhesion to host cells, binding to extracellular mtrix proteins, inhibition of phagocytosis, and induction of angiogenesis. While in vitro studies have proven invaluable for the study of Bh pathogenesis, no Bh virulence factors have been confirmed in vivo and remarkably little is known about how the genes encoding these virulence factors are regulated. To address this problem, we have developed a novel in vivo model of Bh infection using transgenic zebra fish (ZF) embryos that permits us to both monitor infection and host response including angiogenesis. We hypothesize that our ZF embryo model will enable us to: more rigorously test the role of virulence factors that have been defined in vitro; identify ne virulence factors and regulators of virulence in vivo ; and assess the role of these gene products in the host response to Bh infection. To test these hypotheses we propose the following specific aims: 1) Define the role of virulence factors and regulators of virulence in Bh infection using the transgenic ZF embryo model, and 2) Determine the role of Bh virulence factors and regulatory proteins in eliciting a host response to infection in experimentally infected transgenic ZF embryos. An in vivo model is urgently needed to better understand the unique pathogenesis and host response to this bacterium in order to develop novel treatment strategies.