Bifunctional antibodies with targeted CNS delivery against West Nile virus

描述（由申请人提供）：西尼罗河病毒（WNV）在几种脊椎动物物种中引起中枢神经系统（CNS）感染。感染西尼罗河病毒的人可患脑膜炎和脑炎，老年人和免疫功能低下者发生严重神经系统疾病和死亡的风险最大。西尼罗河病毒在全球范围内的新威胁和现有治疗方法的缺乏，需要进行研究，开发有效的治疗方法和生产技术，以便以具有成本意识的方式迅速将候选治疗方法转移到临床护理环境中。我们最近开发了一种植物来源的人源化单克隆抗体，具有良好的治疗潜力，具有理想的人类n -链糖基化模式。这种单抗（hE16）结合到包膜蛋白上高度保守的表位上，并显示出有希望的暴露后治疗活性。尽管如此，我们的研究表明，hE16外周递送在啮齿动物中具有有限的功效窗口：单一给药

DESCRIPTION (provided by applicant): West Nile Virus (WNV) causes infection in the central nervous system (CNS) in several vertebrate animal species. Humans infected with WNV can develop meningitis and encephalitis, and the elderly and immunocompromised are at greatest risk for severe neurological disease and death. New threats of WNV globally and the lack of available treatments warrant studies to develop effective therapeutics and production technologies that can rapidly transfer candidate therapies into the clinical care setting in a cost conscious manner. We recently developed a plant-derived humanized MAb with promising therapeutic potential, with a desired human N-linked glycosylation pattern. This MAb (hE16) binds to a highly conserved epitope on the envelope protein of virtually all isolates worldwide and shows promising post-exposure therapeutic activity. Nonetheless, our studies show that peripheral delivery of hE16 has a limited window of efficacy in rodents: administration of a single dose of hE16 through an intravenous or intraperitoneal route at day 5 post infection or earlier improves survival rates. In comparison, delivery of hE16 directly into the brain at day 6 after infection improved protection against lethal WNV infection in hamsters. Our preliminary data show that a genetically engineered bifunctional MAb variant of hE16 (TfR-Bif) with the potential for enhanced crossing of the blood-brain barrier (BBB) can be expressed in CHO cells or plants. TfR-Bif retains its ability to bind and neutralize WNV, but importantly gains the ability to bind transferrin receptor (TfR) and endocytose into mouse brain endothelial cells. In the R21 phase of this grant, we will use the mouse TfR-specific TfR-Bif as a proof-of-principle in a mouse model of WNV infection. We will test the hypothesis that TfR-Bif can achieve higher levels in the CNS and extends the window of treatment against WNV encephalitis. To address critical safety issues in the brain, we will also identify TfR-Bif glycoforms that offer full bifunctionality with limited or specific Fc receptor (Fc?R) or C1q binding to eliminate potential antibody-dependent enhancement (ADE) of virus infection or pathogenic inflammation. In the R33 phase, we will develop an analogous bifunctional MAb with human therapeutic potential and test if plants provide distinctive advantages in safety, production cost, and scalability for large-scale production under cGMP. In addition to generating novel therapeutic reagents for WNV, this collaborative study will provides a platform for delivery of MAbs to the CNS, which should be applicable to the treatment of other infectious, inflammatory, or neoplastic diseases in the CNS. PUBLIC HEALTH RELEVANCE: This study will generate novel therapeutic reagents for West Nile virus, provide a technology for delivery of therapeutics to the brain, and develop a cost-effective and scalable production technology using plants for protein therapeutics. Such technologies can be applied in the future to combat emerging infectious or non- infectious diseases or bioterrorist threats.