Envelope-receptor interactions in Nipah and Hendra virus pathobiology

新出现的病毒病原体对美国的健康和经济构成了严重威胁。尼帕(尼帕)和亨德拉 (HEV)病毒是副粘病毒科新定义的亨尼帕病毒属的成员。尼帕病毒 (Niv)是一种紧急副粘病毒，可导致高达70%的感染患者发生致命脑炎，以及 越来越多的证据表明艾滋病在人与人之间传播。NIV被指定为世界上最重要的病原体 NIAID生物防御研究议程，如果用于打击农业生物恐怖主义，可能是毁灭性的毒剂 养猪业。内皮合胞体是新城疫病毒感染的一种病原学特征，它是由 由融合(F)和附着(G)包膜糖蛋白组成。NIV受体的鉴定将带来曙光 对新城疫病毒感染的病理生物学进行研究，促进合理开发有效的治疗方法。在我们的 初步的研究结果表明，EphB类受体的膜结合配体ePhinB2 酪氨酸激酶(RTK)，特异性结合于NIV的附着(G)糖蛋白，可溶性Fc融合 但不能有效地阻止NIV的融合和进入。转染腺病毒载体ePhirinB2的研究 不允许的细胞使它们可以进行Niv融合和进入。EPhinB2表达于 内皮细胞和神经元，与已知的NIV的细胞趋向性一致。值得注意的是，NIV信封 抑制微血管内皮细胞和原代大脑皮层神经元的感染 可溶的ewitinB2，但不是相关的ewitinBI蛋白。总而言之，我们的数据表明，ePhrinB2是一种 NIV的功能性受体我们还表明，与NIV相关的蛋白质ewitinB3可以作为一种替代 受体；ewitinB2和B3的不同用法可以解释观察到的不同病原学特征 在尼夫和赫夫之间。识别Niv受体为更全面的分析打开了大门 NIV包膜与受体的相互作用。我们提出以下具体目标，以增加我们的 了解新城疫病毒的病理生物学，并促进抗新城疫疫苗和治疗药物的开发。 它们是：(1)确定ewitinB2/B3中介导与Niv-G相互作用的同源结构域和/或残基 和HEV-G，(2)鉴定NIV-G和HEV-G中的最小受体结合域，并鉴定 参与肾上腺素受体相互作用的关键残基，(3)使用小分子拮抗剂阻断NIV- G与ewitinB2的相互作用，以探索NIV-G和HEV-G中的受体结合部位，以及(4)研究 新型兔抗新城疫病毒单克隆抗体的特性研究公共卫生相关性：Nipah和 亨德拉病毒被指定为优先病原体，是致命的，可以成为生物恐怖主义的破坏者。 和农业恐怖主义(对活畜业的破坏)。识别病毒受体使我们能够更好地 研究病毒是如何进入细胞的。这些调查对于发展有效的反恐怖主义至关重要。 Nipah疫苗和治疗学。

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.