Envelope-receptor interactions in Nipah and Hendra virus pathobiology

新出现的病毒病原体对www.example.com和经济构成严重威胁。尼帕（NiV）和亨德拉 (HeV)病毒是新定义的副粘病毒科亨尼帕病毒属的成员。尼帕病毒 (NiV)是一种紧急的副粘病毒，在高达70%的感染患者中引起致命性脑炎， 有越来越多的证据表明艾滋病毒会在人与人之间传播。NiV被指定为优先病原体， NIAID生物防御研究议程，如果用于对抗 养猪业。内皮合胞体是NiV感染的一种特异性特征， 通过融合（F）和附着（G）包膜糖蛋白。NiV受体的鉴定将揭示 研究NiV感染的病理生物学，并促进有效治疗方法的合理开发。在我们 初步结果表明，ephB类受体的膜结合配体ephrinB2 特异性结合至NiV的附着（G）糖蛋白的酪氨酸激酶（RTK）。 ephrinB2蛋白而不是ephrinB1蛋白有效地阻断了NiV融合和进入。ephrinB2转染入 非允许细胞使它们允许NiV融合和进入。EphrinB2表达于 内皮细胞和神经元，与NiV的已知细胞向性一致。值得注意的是，NiV信封 介导的微血管内皮细胞和原代大鼠皮质神经元的感染被抑制， 可溶性ephrinB2，而非相关ephrinB1蛋白。累积起来，我们的数据显示ephrinB2是一种 我们还表明，ephrinB3，一个相关的蛋白质，可以作为一种替代， 受体; ephrinB2与B3的差异使用可以解释观察到的变异致病谱 在NiV和HeV之间。识别NiV受体为更全面的分析打开了大门。 NiV病毒与受体的相互作用我们提出以下具体目标，以提高我们的 这有助于理解NiV病理生物学，并促进抗NiV疫苗和治疗剂的开发。 它们是：（1）鉴定ephrinB2/B3中介导与NiV-G相互作用的同源结构域和/或残基 （2）对NiV-G和HeV-G的最小受体结合结构域进行了表征， 参与肝配蛋白受体相互作用的关键残基，（3）使用阻断NiV-的小分子拮抗剂， G与ephrinB2的相互作用，以探测NiV-G和HeV-G中的受体结合位点，以及（4）研究 抗NiV-G的新型兔单克隆抗体的性质。公共卫生相关性：尼帕和 亨德拉病毒是指定的优先病原体，是致命的，可以摧毁生物恐怖主义的代理人 农业恐怖主义（破坏畜牧业）。识别病毒受体可以让我们更好地 研究病毒如何进入细胞。这些研究对发展有效的反- 尼帕疫苗和治疗剂。

Emerging viral pathogens present a critical threat to U.S.health and economy. Nipah (NiV) and Hendra (HeV) viruses are members of the newly defined Henipavirus genus of the Paramyxoviridae. Nipah virus (NiV) is an emergent paramyxovirus that causes fatal encephalitis in up to 70% of infected patients, and there is increasing evidence of human-to-human transmission. NiV is designated a priority pathogen in the NIAID Biodefense Research Agenda, and could be a devastating agent of agrobioterrorism if used against the pig farming industry. Endothelial syncytia is a pathognomonic feature of NiV infections, and is mediated by the fusion (F) and attachment (G) envelope glycoproteins. Identification of the NiV receptor will shed light on the pathobiology of NiV infection, and spur the rational development of effective therapeutics. In our preliminary results, we show that ephrinB2, the membrane bound ligand for the ephB class of receptor tyrosine kinases (RTKs), specifically bound to the attachment (G) glycoprotein of NiV.Soluble Fc-fusion proteins of ephrinB2 but not ephrinBI effectively blocked NiV fusion and entry. Transfection of ephrinB2 into non-permissive cells rendered them permissive for NiV fusion and entry. EphrinB2 is expressed on endothelial cells and neurons, consistent with the known cellular tropism for NiV. Significantly, NiV envelope mediated infection of microvascular endothelial cells, and primary cortical rat neurons, was inhibited by soluble ephrinB2, but not the related ephrinBI protein. Cumulatively, our data show that ephrinB2 is a functional receptor for NiV.We also show that ephrinB3, a related protein, can serve as an alternative receptor; differential usage of ephrinB2 versus B3 may explain the variant pathogenic profiles observed between NiV and HeV. Identifying the NiV receptor opens the door for a more comprehensive analysis of the NiV envelope-receptor interactions. We propose the following Specific Aims to increase our understanding of NiV pathobiology, and facilitate the development of anti-NiV vaccines and therapeutics. They are: (1) Identify cognate domains and/or residues in ephrinB2/B3 that mediate interactions with NiV-G and HeV-G, (2) Characterize the minimal receptor binding domain in NiV-G and HeV-G, and identify the critical residues involved in ephrin receptor interactions, (3) Use small molecule antagonists that block NiV- G's interaction with ephrinB2 to probe the receptor binding site in NiV-G and HeV-G, and (4) Investigate the properties of novel rabbit monoclonal antibodies against NiV-G. Public Health Relevance: Nipah and Hendra viruses are designated priority pathogens, are deadly, and can be devasting agents of bioterrorism and agroterrorism (devastation of the live-stock industry). Identifying the virus receptor allows us to better study how the virus gets into cells. These investigations are crucial to the development of effective anti- Nipah vaccines and therapeutics.