A structural approach to the study of viral Immune interference mechanisms

描述（由申请方提供）：病毒免疫evasins是病毒在感染期间破坏宿主免疫反应的关键分子。了解它们功能的分子基础是解释病毒如何适应特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）具有一组这样的蛋白质，其特异性地干扰主要组织相容性复合物I类（MHC-I）抗原呈递至CD 8 + T细胞和自然杀伤（NK）细胞。尽管有大量的遗传和功能研究，免疫evasin特异性和功能的结构生物学知之甚少，主要是由于这些蛋白质及其配体共结晶的瓶颈。为了绕过这个瓶颈，我开发了一种新方法，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。这种混合方法现在允许在30 kD-50 kD范围内精确测定蛋白质复合物的结构，这是以前单独使用NMR技术无法达到的尺寸。我已经应用这种方法来阐明MCMV m04免疫evasin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。这些结构研究可以以原子细节揭示m04与MHC-I的相互作用模式，从而帮助解决关于MCMV m04免疫evasin的功能的长期难题，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相互作用的结构方面和可塑性，我的目的是确定MHC-I上细胞表面免疫受体的几个独特结合位点中的哪一个被与m04的相互作用阻断。因此，解读m04与MHC结合的机制将阐明m04对特定MHC同种异型的特异性的基础，并提供关于干扰抗原呈递给T细胞和NK细胞的复合物的功能的见解。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，该病毒在免疫系统受损的个体（如HIV患者和移植受体）中引起一系列先天性感染和疾病。通过阐明CMV绕过免疫反应并建立感染状态的关键机制，这项研究将为HMCV感染提供见解，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.