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

描述(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，占全世界儿童死亡的近五分之一(20%)，每年导致200-300万儿童死亡。在美国，人类副流感病毒和呼吸道合胞病毒(RSV)是导致儿童咽喉炎、毛细支气管炎和肺炎的主要原因，但目前还没有药物或疫苗可用。由于对这些病毒基础知识的空白，针对这些病毒的抗病毒药物的开发在该领域一直是一个巨大的挑战。我们建议应用基础研究成果来开发一种基于抑制病毒进入过程中融合的新的抗病毒策略。融合抑制肽可以阻断病毒融合中间体，防止病毒侵入和感染。我们已经证明了多肽抑制剂对副粘病毒(如副流感和呼吸道合胞病毒)的有效性取决于三个变量：(I)多肽与目标融合蛋白的相互作用强度；(Ii)获得目标序列的时间窗口；(Iii)多肽在目标融合蛋白附近的位置。我们建议利用这一新信息开发高效的多肽融合抗病毒药物，以抑制这两种重要的儿科呼吸道病原体；研究融合抑制剂的耐药性机制以避免耐药性；并在有效的动物疾病模型中检验这些假设。因此，我们将确定这些融合抑制物在体内的潜力。(1)抗副流感和抗呼吸道合胞病毒融合抑制多肽的设计和检测，靶向发生融合的质膜。(A)将利用生物物理数据和晶体结构分析来加强多肽抑制剂与F的结合。(B)有效的多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，以加强它们的作用。我们将确定，我们通过在多肽中添加胆固醇基团而发现的疗效增加是否是由于膜表面有效浓度的普遍增加，和/或病毒进入的脂筏中的特定浓缩。(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高效多肽抑制剂的耐药性决定因素，以及是否通过在F激活的早期阶段靶向多肽或通过增加受体结合位置的抑制剂浓度来减少对耐药性的选择。(3)修饰多肽抑制剂的体内效应。有效的多肽将在棉鼠体内进行测试，以确定将这些抑制剂开发为临床有用的抗病毒药物的可取性。儿童呼吸道病毒的有效治疗将降低美国儿童的医疗保健成本，并将显著影响儿童健康。 公共卫生相关性：急性呼吸道感染现在是5岁以下幼儿死亡的主要原因，占全世界儿童死亡的近五分之一(20%)，每年导致200-300万儿童死亡。人类副流感病毒和呼吸道合胞病毒是美国儿童哮喘、毛细支气管炎和肺炎的主要原因。尽管这些疾病对世界各地婴儿的疾病和住院造成了巨大影响，但没有药物或疫苗可用。由于对这些病毒基础知识的空白，针对这些病毒的抗病毒药物的开发在该领域一直是一个巨大的挑战。我们建议应用基础研究的结果来开发一种新的抗病毒策略，即在病毒进入过程中抑制融合。儿童呼吸道病毒的有效治疗将显著降低美国儿童的医疗保健成本，并极大地影响儿童健康。

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.