Retrovirus Entry and Virus Evolution

超出所提供的空间。逆转录病毒作为一种良性的基因传递载体已成为重要的研究工具，在基因治疗方面具有潜在的治疗载体。无论是致病性的还是治疗性的，病毒的初始感染和随后的传播取决于逆转录病毒有效地进入宿主细胞。虽然对任何逆转录病毒的病毒进入机制的详细了解还没有明确定义，但所有逆转录病毒都有一个共同的进入细胞的总体策略。逆转录病毒进入的第一步，即病毒表面糖蛋白（SU）与细胞受体之间的相互作用，是复杂的，涉及两种蛋白质中多个不连续的决定因素，这些决定因素指定受体选择、结合亲和力和触发病毒糖蛋白构象变化的能力。尽管这种相互作用很复杂，但逆转录病毒有能力进化其包膜糖蛋白的结构，以使用不同的细胞蛋白作为受体，通常是一种与原始受体没有明显同源性的蛋白质，并保留有效的进入功能。逆转录病毒是如何做到的呢？了解这种能力将为抗病毒干预和靶向基因传递提供有价值的信息。我们假设：(1)包膜糖蛋白被组织成功能区域，允许通过突变和/或重组发生受体选择的变化，同时保持受体结合亲和力和触发糖蛋白构象变化以启动融合过程的能力的临界水平；(2)位于SU高变结构域的多个不连续受体相互作用决定因素需要结合亲和力并限制或扩大受体的使用；(3) SU高变结构域外的区域将连接受体结合触发糖蛋白锁定机制，并随着病毒改变受体使用而保守。同源的逆转录病毒群，从A到E （A-E）禽类白血病病毒（ALV）亚群，提供了一个强大的模型系统，通过提供从共同祖先进化而来利用不同受体的高度相关病毒，来检验这些假设。具体来说，我们的目标是：1。从基因上确定A-E亚群ALV包膜糖蛋白的功能区域/残基，这对受体结合亲和力很重要。2. 从遗传学上确定A-E ALV糖蛋白亚群的功能区域/残基，这对受体使用的特异性很重要。3. 识别和表征ALV糖蛋白中对连接受体结合触发启动融合过程的构象变化重要的区域/残基。4. 基因定义ALV受体的功能区域/残基，这是结合亲和力和触发ALV糖蛋白构象变化所必需的。5. 测试ALV糖蛋白的可溶性形式，以产生适合结构研究的晶体。PERFORMANCESITE ( ======================================== 节结束 ===========================================

EXCEED THE SPACE PROVIDED. Retroviruses, which include many important pathogens of humans and animals, have become important research tools as benign gene delivery vectors, and have potential as therapeutic vectors for gene therapy. Whether pathogenic or therapeutic, the initial infection and subsequent dissemination of the virus depends on efficient entry of the retrovirus into host cells. While a detailed understanding of the mechanisms of viral entry has not been clearly defined for any retrovirus, all retroviruses share a common overall strategy for entry into cells. The initial step of retrovirus entry, the interaction between the viral surface glycoprotein (SU) and a cellular receptor, is complex, involving multiple, noncontiguous determinants in both proteins that specify receptor choice, binding affinity and the ability to trigger conformational changes in the viral glycoproteins. Despite the complexity of this interaction, retroviruses have the ability to evolve the structure of their envelope glycoproteins to use a different cellular protein as a receptor, often a protein that has no obvious homology to the original receptor, and retain efficient entry functions. How do retroviruses do this? Understanding this ability will provide valuable information for antiviral intervention and targeting gene delivery. We hypothesize that: (1) the envelope glycoproteins are organized into functional domains that allow changes to occur in receptor choice by mutation and/or recombination while maintaining a critical level of both receptor binding affinity and the ability to trigger glycoprotein conformational changes to initiate the fusion process; (2) multiple, noncontiguous receptor interaction determinants located in the SU hypervariable domains are required for binding affinity and to restrict or broaden receptor usage; (3) regions outside of the SU hypervariable domains will function to connect receptor binding to triggering the glycoprotein lock mechanism and will be conserved as the virus changes receptor usage. The homologous group of retroviruses, the subgroups A through E (A-E) avian leukosis viruses (ALV), provide a powerful model system to test these hypotheses by supplying highly related viruses that have evolved from a common ancestor to utilize different receptors. Specifically, we aim to: 1. Genetically define functional regions/residues of the subgroup A-E ALV envelope glycoproteins important for receptor binding affinity. 2. Genetically define functional regions/residues of the subgroup A-E ALV glycoproteins important for the specificity of receptor usage. 3. Identify and characterize regions/residues in the ALV glycoproteins important for connecting receptor binding to triggering the conformational changes that initiate the fusion process. 4. Genetically define functional regions/residues of the ALV receptors necessary for binding affinity and triggering a conformational change in the ALV glycoproteins. 5. Test soluble forms of the ALV glycoproteins for the ability to produce crystals suitable for structural studies. PERFORMANCESITE( ========================================Section End===========================================