Prophylactic Immunotherapy for Marburg Virus Disease Outbreak Control

埃博拉病毒（EBOV、SUDV、BDBV）和马尔堡病毒（MARV和RAVV）引起周期性暴发， 具有极高死亡率的严重病毒性出血热。2013-2016年埃博拉病毒病（EVD）爆发 在西非的一次会议上，强调了丝状病毒流行病的严重性及其区域和全球影响。这 疫情的爆发给处于疫情控制第一线的人们造成了巨大的损失，医生、护士、医院 人员、社会工作者和其他支持人员。许多护士和医生在帮助病人时丧生 许多人因为害怕暴露而离开了他们的职业。当地医疗保健系统的几近崩溃， 助长了病毒在该地区的传播因此，对第一反应者的保护必须是一个高 这是一个优先事项，对于成功控制疫情至关重要。目前，虽然预防性疫苗可用于 对于EVD，没有治疗或预防措施可用于马尔堡病毒病（MVD）， 导致了多次疫情爆发，最近的一次是2022年6月。本建议的目的是制定一个有效的 免疫预防剂用于保护第一应答者免受MVD。这样的产品必须1）非常有效 以实现经济上可负担得起的低剂量水平，和2）具有延长的生物利用度，以提供合理的 保护期长。我们和其他人已经分离出几类中和性单克隆抗体 （mAb）用于埃博拉病毒。然而，对于马尔堡病毒，只有一类针对糖蛋白（GP）的mAb， 已经描述了它们都靶向MARV和RAVV的受体结合位点（RBS）内的单个表位 GP.现在，使用一种新的免疫和B细胞选择方法与合理设计的抗原，我们有 成功地鉴定了一类新的单克隆抗体，其结合新的表位并在亚- 至低nM浓度，比RBS结合剂的效力高100倍。先导抗体R217具有 被选择并显示在小鼠、豚鼠和非人灵长类动物（NHP）中保护免于MVD。在这 SBIR项目我们建议通过引入 在FcRn结合区中的突变（YTE），以延长抗体的半衰期并评估抗体的效力。 该产品.在目标1中，R217-YTE将在ExpiCHO细胞中生产并充分表征。药动 (PK)将在NHP中进行评估。在目标2中，将在以下环境中评价R217-YTE对MVD的疗效 暴露前和暴露后预防措施的剂量水平和血清中和活性， 保护将被确定。目标3将侧重于在CHO中生成稳定的生产细胞系 细胞和研究细胞库，用于生产未来的GMP细胞库。如果成功，我们预计 在DoD或巴尔达资助下进一步开发产品，并根据FDA动物法规获得批准。

The ebolaviruses (EBOV, SUDV, BDBV) and marburgviruses (MARV and RAVV), cause periodic outbreaks of severe viral hemorrhagic fever with very high mortality rates. The 2013-2016 Ebola virus disease (EVD) outbreak in West Africa highlighted the serious nature of a filovirus epidemic and its regional and global implications. This outbreak took an enormous toll on people at the front line of the epidemic control, i.e., physicians, nurses, hospital personnel, social workers, and other support staff. Many nurses and physicians lost their lives helping patients and many left their profession out of fear of exposure. The near breakdown of the local healthcare system further fueled the spread of the virus across the region. Therefore, protection of the first responders must be a high priority and is critical for successful outbreak control. Currently, while a prophylactic vaccine is available for EVD, there are no therapeutic or prophylactic countermeasures available for Marburg virus disease (MVD) which has led to many outbreaks and as recently as June 2022. The objective of this proposal is to develop an effective immunoprophylactic for protection of first responders against MVD. Such a product mut be 1) extremely potent to enable economically affordable low dose levels, and 2) have extended bioavailability to provide a reasonably long duration of protection. We and others have isolated several classes of neutralizing monoclonal antibodies (mAbs) for ebolaviruses. However, for marburgviruses only a single class of mAbs against the glycoprotein (GP) has been described that all target a single epitope within the receptor binding site (RBS) of MARV and RAVV GP. Now, using a novel immunization and B cell selection approach with rationally designed antigens we have succeeded in identifying a new class of mAbs that bind to a novel epitope and neutralize marburgviruses at sub- to low-nM concentrations and are up to 100-fold more potent than the RBS binders. A lead antibody, R217, has been selected and shown to protect against MVD in mice, guinea pigs, and nonhuman primates (NHPs). In this SBIR project we propose to engineer the Fc portion of this macaque-human chimeric antibody by introducing mutations (YTE) in the FcRn binding region to extend the half-life of the antibody and evaluate the efficacy of the product. In Aim 1 R217-YTE will be produced in ExpiCHO cells and fully characterized. Pharmacokinetics (PK) will be evaluated in NHPs. In Aim 2, the efficacy of R217-YTE against MVD will be evaluated in the settings of pre- and post-exposure prophylaxis and the required dose level and serum neutralization activity required for protection will be determined. Aim 3 will be focused on generation of a stable manufacturing cell line in CHO cells and a research cell bank to be used for production of future GMP cell banks. If successful, we anticipate further development of the product under DoD or BARDA funding and approval under FDA Animal Rule.