FH-Fc as a Pre-Exposure Prophylactic for Tickborne Disease

莱姆病(LD)是美国最流行的媒介传播疾病，多达30万人 一年的案子。该病是由几种伯氏疏螺旋体细菌引起的。 莱姆疏螺旋毛虫)，由动物(鸟类、啮齿动物)宿主的壁虱传播。当一个 在相当数量的LD患者中，短程抗生素通常能有效地消除细菌 继续遭受长期的、使人衰弱的后遗症，包括疼痛、疲劳、认知功能障碍和其他 症状称为治疗后莱姆病(PTLD)。在美国，多达190万人患有 PTLD。目前还没有可以预防LD或PTLD的疫苗。 我们正在开发一种针对LD和其他扁虱传播疾病(TBD)的免疫预防药物，其基础是 了解致病病原体用来逃避先天免疫的毒力机制。这些 病原体通过与人类结合来保护自己免受人类补体系统的消灭 补体抑制因子H(FH)，一种在血液中含量丰富的蛋白质。结合在细菌表面的FH可以阻断细菌表面的 激活替代补体途径，否则将摧毁细菌。我们已经制作了 重组蛋白是与莱姆疏螺旋体结合的FH结构域与恒定区 人IgG1(Fc)，使用植物表达系统。这些融合蛋白(ScR6、7/Fc和Scr(18-20)/Fc)结合 莱姆疏螺旋体，在人类补体存在的情况下，杀死细菌。Fc给了蛋白质一个很长的 半衰期，这可能使他们被用作暴露前预防(PrEP)，以防止LD和TBD。 此第一阶段SBIR的总体目标是展示SCR6、7/FC和SCR(18-20)/FC在 在LD小鼠模型中预防莱姆疏螺旋体感染，并确定最小有效剂量。该项目 是三个研究小组的合作，他们唯一有资格成功地完成这项工作。行星 生物技术(小型企业)将生产SCR6、7/FC和SCR(18-20)/FC以及两种新型FC 这两种蛋白质的变种旨在增强补体激活。凯瑟琳·布里塞特，加州大学 北达科他州将评估这些蛋白质介导补体依赖的莱姆和 复发性发热、膜攻击复合体螺旋体和人巨噬细胞吞噬调理作用。易-- 纽约州卫生局的Pin Lin将评估这些蛋白质阻止感染的能力 当老鼠被携带有毒力的莱姆疏螺旋体菌株的扁虱叮咬时。小鼠实验的目的是 两者都确定了最有效的ScR6、7/Fc和Scr(18-20)/Fc变体，并确定了100%的最小剂量 在扁虱挑战前1天注射可有效阻断感染。如果成功，我们将展示 FH/FC融合作为LD和潜在的其他待定疾病的PrEP的商业潜力。

Lyme disease (LD) is the most prevalent vector-borne disease in the United States, with up to 300,000 cases a year. LD is caused by several species of the spirochete bacteria Borrelia burgdorferi sensu lato (the Lyme borreliae), which are transmitted by ticks from animal (bird, rodent) reservoirs to human hosts. While a short course of antibiotics is usually effective in eliminating the bacteria a sizeable number of LD patients continue to suffer long-term, debilitating sequelae, including pain, fatigue, cognitive dysfunction and other symptoms known as post-treatment Lyme disease (PTLD). As many as 1.9 million people in the US suffer from PTLD. There is currently no vaccine that can prevent LD or PTLD. We are developing an immunoprophylactic for LD and other tick-borne diseases (TBD) based on an understanding of the virulence mechanisms that the causal pathogens use to evade innate immunity. These pathogens protect themselves from elimination by the human complement system by binding to the human complement inhibitor Factor H (FH), a protein abundant in blood. FH bound to bacterial surfaces blocks the activation of the alternative complement pathway that would otherwise destroy the bacteria. We have produced recombinant proteins that are fusions of the FH domains that bind to Lyme borreliae with the constant region of human IgG1 (Fc), using a plant expression system. These fusion proteins (SCR6,7/Fc and SCR(18-20)/Fc) bind to Lyme borreliae and, in the presence of human complement, kill the bacteria. The Fc gives the proteins a long half-life, which may allow them to be used as a pre-exposure prophylactic (PrEP) to prevent LD and TBDs. The overall goal of this Phase I SBIR is to demonstrate the efficacy of SCR6,7/Fc and SCR(18-20)/Fc in preventing Lyme borreliae infection in a mouse model of LD and determine a minimal effective dose. The project is a collaboration of three research groups that are uniquely qualified to bring it to a successful conclusion. Planet Biotechnology (the small business concern) will produce SCR6,7/Fc and SCR(18-20)/Fc and two novel Fc variants of both proteins designed to enhance complement activation. Catherine Brissette at the University of North Dakota will evaluate the ability of the proteins to mediate complement-dependent killing of Lyme and relapsing fever spirochetes by membrane attack complex and opsonophagocytosis by human macrophages. Yi- Pin Lin at the New York State Department of Health will evaluate the ability of the proteins to block infection when mice are bitten by ticks carrying a virulent Lyme borreliae strain. The mouse experiments are designed to both identify the most potent SCR6,7/Fc and SCR(18-20)/Fc variant and identify the minimal dose that is 100% effective in blocking infection when injected 1 day prior to tick challenge. If successful, we will have demonstrated the commercial potential of an FH/Fc fusion as a PrEP for LD and potentially other TBD.