A structural approach to the study of viral Immune interference mechanisms

描述（申请人提供）：病毒免疫逃避素是病毒在感染过程中破坏宿主免疫反应的关键分子。了解其功能的分子基础是解释病毒如何适应特异性感染选定宿主以及设计新疫苗和其他抗病毒疗法的关键。小鼠巨细胞病毒（MCMV）有一组这样的蛋白，它们特异性地干扰主要组织相容性复合体I类（MHC-I）抗原向CD8+ T细胞和自然杀伤（NK）细胞的递呈。尽管有大量的遗传和功能研究，但由于这些蛋白质及其配体共结晶的瓶颈，对免疫逃避蛋白特异性和功能的结构生物学知之甚少。为了绕过这个瓶颈，我开发了一种新的方法，将核磁共振（NMR）光谱记录的稀疏数据集与复杂的Rosetta建模方法相结合。这种混合方法现在可以精确地确定30kD-50kD范围内的蛋白质复合物的结构，这是以前单独使用核磁共振技术无法达到的大小。我已经应用这种方法阐明了MCMV m04免疫逃避蛋白的溶液结构。我现在建议扩展这些方法来确定m04/MHC-I复合物的结构。这些结构研究可以在原子细节上揭示m04与MHC-I相互作用的模式，从而有助于解决关于MCMV m04免疫逃避蛋白功能的长期难题，即为什么m04增强MHC-I表面表达而不是减少它？通过分析m04/MHC-I相互作用的结构和可塑性，我的目标是确定MHC-I上细胞表面免疫受体的几个独特结合位点中哪些被与m04的相互作用阻断。因此，破译m04与MHC结合的机制将阐明m04对特定MHC同种异体特异性的基础，并深入了解该复合物在干扰抗原向T细胞和NK细胞递呈方面的功能。虽然MCMV只感染小鼠，但它促进了相关人类病毒（HCMV）的许多重要发现，HCMV在免疫系统受损的个体（如HIV患者和移植接受者）中引起一系列先天性感染和疾病。通过阐明cmv绕过免疫应答并建立感染状态的关键机制，本研究将为HMCV感染提供新的见解，并进一步推进基于结构的病毒免疫干扰蛋白研究的新技术。

DESCRIPTION (provided by applicant): Viral immunoevasins are key molecules employed by viruses to subvert the host immune response during infection. Understanding the molecular basis of their functions is key for explaining how viruses have adapted to specifically infect selected hosts and for the design of new vaccines and other antiviral therapies. Mouse cytomegalovirus (MCMV) has a set of such proteins that specifically interfere with major histocompatibility complex class I (MHC-I) antigen presentation to CD8+ T cells and natural killer (NK) cells. Notwithstanding the large number of genetic and functional studies, the structural biology of immunoevasin specificities and functions is poorly understood, due largely to bottlenecks in co-crystallizing these proteins and their ligands. To bypass this bottleneck I have developed a new approach that combines sparse datasets recorded from nuclear magnetic resonance (NMR) spectroscopy with sophisticated Rosetta modeling methods. This hybrid approach now permits accurate structure determination of protein complexes in the 30kD-50kD range, a size previously unapproachable by NMR techniques alone. I have already applied this approach to elucidate the solution structure of the MCMV m04 immunoevasin. I now propose to extend these methods to determine the structures of m04/MHC-I complexes. These structural investigations can reveal, in atomic detail, the mode of interaction of m04 with MHC-I thereby helping to resolve a longstanding puzzle regarding the function of the MCMV m04 immunoevasin, i.e. why does m04 enhance MHC-I surface expression instead of diminishing it? By analyzing structural aspects and the plasticity of the m04/MHC-I interaction, I aim to identify which of the several unique binding sites on MHC-I for cell surface immune receptors are blocked by the interaction with m04. Therefore, deciphering the mechanism of m04 binding to MHC will elucidate the basis of m04 specificity for particular MHC allotypes and provide insight into the function of the complex with respect to interfering with antigen presentation to T cells and NK cells. Although MCMV only infects mice, it has facilitated many important discoveries for the related human virus (HCMV), which causes a range of congenital infections and diseases in individuals with compromised immune systems (such as HIV patients and transplant recipients). By elucidating a key mechanism by which CMVs bypass immune responses and establish an infectious state, this study will provide insight to HMCV infection and further advance a new technology for structure-based studies of viral immune-interfering proteins.