New fusion inhibitors for childhood respiratory viruses, designed to avoid resist

描述（由申请人提供）：急性呼吸道感染现在是5岁以下幼儿死亡的主要原因，占全世界儿童死亡人数的近五分之一（20%），每年导致200万至300万儿童死亡。在美国，人类副流感病毒和呼吸道合胞病毒（RSV）是大多数儿童群、毛细支气管炎和肺炎的病因，但没有药物或疫苗可用。由于缺乏对这些病毒的基本知识，开发针对这些病毒的抗病毒药物一直是该领域的一大挑战。我们建议应用基础研究成果，开发一种基于抑制病毒进入融合的抗病毒新策略。融合抑制肽可以阻断病毒融合中间体，阻止病毒进入和感染。我们已经证明，肽抑制剂对副粘病毒（如副流感和RSV）的疗效取决于三个变量：(i)肽与目标融合蛋白相互作用的强度；（ii）获取目标序列的时间窗口；（iii）肽在目标融合蛋白附近的位置。我们建议利用这一新信息来开发高效的肽融合抗病毒药物，抑制这两种重要的儿童呼吸道病原体；探讨融合抑制剂耐药机制，避免耐药；并在有效的动物疾病模型中验证这些假设。因此，我们将确定这些融合抑制剂的体内潜力。(1)设计抗副流感病毒和抗呼吸道合胞病毒融合抑制肽，并检测靶向融合发生的质膜。(a)生物物理数据和晶体结构分析将用于增强肽抑制剂与F的结合。(b)有效肽将靶向发生融合的质膜，增加它们进入F七肽重复区域的途径，以增强它们的作用。我们将确定通过在多肽中添加胆固醇基团所发现的增强的功效是否由于膜表面有效浓度的普遍增加，和/或在病毒进入的脂筏中特异性富集。(2)病毒耐药性的决定因素：避免耐药性的机制和策略。我们将评估对膜锚定的高效肽抑制剂的抗性决定因素，以及是否通过在f激活的早期阶段靶向肽或通过增加受体结合位置的抑制剂浓度来减少抗性的选择。(3)修饰肽抑制剂的体内疗效。有效肽将在棉花大鼠体内进行测试，以确定开发这些抑制剂作为临床有用的抗病毒药物的可取性。对儿童呼吸道病毒的有效治疗将降低美国儿童的医疗保健费用，并将显著影响儿童健康。

DESCRIPTION (provided by applicant): Acute respiratory infection is now the leading cause of mortality in young children under 5 years of age, accounting for nearly one fifth (20%) of childhood deaths worldwide, and killing 2-3 million children each year. Human parainfluenza viruses and respiratory syncytial virus (RSV) cause the majority of childhood croup, bronchiolitis and pneumonia in the U.S., yet no drugs or vaccines are available. Development of antiviral drugs for these viruses has been a great challenge in the field because of gaps in fundamental knowledge about these viruses. We propose to apply fundamental research results in order to develop a new antiviral strategy based on inhibiting fusion during viral entry. Fusion inhibitory peptides can block viral fusion intermediates to prevent entry and infection. We have shown that the efficacy of peptide inhibitors for paramyxoviruses (such as parainfluenza and RSV) depends on three variables: (i) Strength of interaction of the peptide with the target fusion protein; (ii) Time window of access to the target sequence; (iii) Location of the peptide in proximity to the target fusion protein. We propose to use this new information to develop highly effective peptide fusion antivirals that inhibit both of these two important pediatric respiratory pathogens; to investigate the mechanisms of resistance to fusion inhibitors so as to avoid resistance; and to test these hypotheses in a valid animal model of disease. We will thus establish the in vivo potential of these fusion inhibitors. (1) Design and testing of anti-parainfluenza and anti-respiratory syncytial virus fusion inhibitory peptides targeted to the plasma membrane where fusion occurs. (a) Biophysical data and crystal structure analysis will be used to enhance peptide inhibitor binding to F. (b) Effective peptides will be targeted to the plasma membrane where fusion occurs, increasing their access to the F heptad repeat region, in order to enhance their action. We will determine whether the increased efficacy that we find by adding a cholesterol group to peptides is due to a generic increase of the effective concentration at the membrane surface, and/or a specific enrichment in lipid rafts, where virus entry occurs. (2) Determinants of viral resistance: Mechanisms and strategies for avoiding resistance. We will assess the determinants of resistance to membrane-anchored highly effective peptide inhibitors, and whether selection for resistance is reduced by targeting with peptides an earlier stage of F-activation, or by increasing the concentration of inhibitor at the location of receptor binding. (3) In vivo efficacy of modified peptide inhibitors. Effective peptides will be tested in vivo in the cotton rat, to establish the desirability of developing these inhibitors as clinically useful antiviral agents. Effective therapy for pediatric respiratory viruses would decrease the cost of health care for children in the U.S. and would significantly impact child health. PUBLIC HEALTH RELEVANCE: Acute respiratory infection is now the leading cause of mortality in young children under 5 years of age, accounting for nearly one fifth (20%) of childhood deaths worldwide, and killing 2-3 million children each year. Human parainfluenza viruses and respiratory syncytial virus cause the majority of childhood croup, bronchiolitis and pneumonia in the U.S. Despite the huge impact of these diseases on illness and hospitalization of young infants worldwide, no drugs or vaccines are available. Development of antiviral drugs for these viruses has been a great challenge in the field because of gaps in fundamental knowledge about these viruses. We propose to apply the results of fundamental research to develop a new antiviral strategy based on inhibiting fusion during viral entry. Effective therapy for pediatric respiratory viruses would significantly decrease the cost of health care for children in the U.S. and tremendously impact child health.