Carbohydrate-based Antiinfective Agents

描述（由申请人提供）：基于碳水化合物的抗感染药物可以破坏复杂的碳水化合物识别事件，这对病原体的感染机制至关重要，代表了尚未开发的治疗财富。基于碳水化合物的抗感染的前景是，它们不太容易进化成微生物耐药性，因为碳水化合物配体本身是不变的，而碳水化合物识别对致病功能至关重要。因此，以碳水化合物为基础的抗感染药物可以更好地阻止耐药微生物菌株进化所带来的迫在眉睫的公共卫生威胁。拟议研究的目标是专门开发新的以碳水化合物为基础的抗感染药物，以解决最近出现的致病菌和流感耐药菌株，具体包括两个目标：1)细菌转糖基化酶，以及2)流感外衣蛋白血凝素和神经氨酸酶。转糖基化酶（TGase）是负责组装细菌细胞壁碳水化合物骨架的酶：它是必不可少的，可接近的，并且由于它识别肽聚糖的不变低聚糖骨架，因此不易产生抗生素耐药性。我们的努力已经为TGase期待已久的抗生素开发做好了准备，用于对抗危险的革兰氏阳性菌株耐甲氧西林金黄色葡萄球菌（MRSA）和耐万古霉素肠球菌（VRE）。此外，由于多重和广泛耐药结核分枝杆菌（MDR-/XDR-TB）的惊人增长，将建立结核分枝杆菌TGase，用于开发抗结核药物。针对革兰氏阳性和分枝杆菌tgase，提出了专门合成碳水化合物基底物类似物、过渡态抑制剂和新型药物样基序的途径。血凝素（HA）和神经氨酸酶（NA）是流感外衣糖蛋白，易受唾液酸衍生物的抑制，从而干扰对唾液苷（即以唾液酸结尾的复合碳水化合物）的必要识别。它们也是适应性免疫反应的靶标，可以产生针对抗原蛋白表位的中和抗体，特别是HA。需要改进抑制和免疫战略，因为病毒突变率高导致对抗流感药物产生耐药性（例如，2009年6级大流行爆发期间迅速出现了对达菲具有耐药性的“猪流感”）和抗原漂移（即逃离保护性免疫）。迫在眉睫的大流行病威胁进一步加速了这一需求。本文设计的抗流感药物的重点是建立更高的耐药屏障，并了解耐药突变如何影响na -唾液苷的相互作用。提出了一种碳水化合物修饰的透明质酸蛋白疫苗的策略，其重点是最大化交叉反应性免疫。

DESCRIPTION (provided by applicant): Carbohydrate-based anti-infective agents can disrupt complex carbohydrate recognition events vital to the infective mechanisms of pathogens, representing an untapped wealth of therapeutics. The promise of carbohydrate-based anti-infective is that they are less prone to the evolution of microbial resistance, because, carbohydrate ligands themselves are invariant, and carbohydrate recognition is essential to pathogenic function. As such, carbohydrate-based anti-infective can better thwart the looming public health threats posed by the evolution of resistant microbial strains. The goals of the proposed research are to specifically develop new carbohydrate-based anti-infective agents that address the recent rise of resistant strains of pathogenic bacteria and influenza, as detailed in two aims targeting: 1) bacterial transglycosylase, and 2) the influenza coat proteins hemagglutinin and neuraminidase. Transglycosylase (TGase) is the enzyme responsible for assembling the carbohydrate backbone of the bacterial cell wall: it is essential, accessible, and less prone to evolving antibiotic resistance due to its recognition of the invariant oligosaccharide backbone of the peptidoglycan. Our efforts have primed TGase for long-awaited antibiotic development against dangerous gram-positive strains of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). In extension, the Mycobacterial TGase will be established for the development of anti-tuberculosis agents, which are in great need due to the alarming rise of multi- and extensively-drug resistant Mycobacterium tuberculosis (MDR-/XDR-TB). Routes for the specialized synthesis of carbohydrate-based substrate analogs, transition state inhibitors, and novel drug- like motifs are proposed for targeting gram-positive and Mycobacterial TGases. Hemagglutinin (HA) and neuraminidase (NA) are influenza coat glycoproteins that are susceptible to inhibition by sialic acid derivatives, which interfere with necessary recognition of sialosides (i.e. complex carbohydrates that end with a sialic acid). They are also targets of the adaptive immune response, which can generate neutralizing antibodies to antigenic protein epitopes, particularly with HA. Strategies for inhibition and immunization need to be improved, as high rates of viral mutation lead to resistance against antiinfluenza agents (e.g., the rapid emergence of Tamiflu resistant "swine flu" during the 2009 level-6 pandemic outbreak) and antigenic drift (i.e., escape from protective immunity). Looming pandemic threats further hasten this need. Antiinfluenza agents are designed herein with focus on establishing a higher barrier to resistance and understanding how resistant mutations affect NA-sialoside interactions. A strategy for a carbohydrate-modified HA protein vaccine is presented, with attention directed toward maximizing cross-reactive immunity. PUBLIC HEALTH RELEVANCE: Anti-infective agents are essential to preserving public health, but are increasingly compromised by the evolution of microbial resistance. This proposal is centered on developing carbohydrate-based anti-infective agents that can disrupt or exploit invariant carbohydrate recognition processes critical to pathogen survival and infectivity, leading to important new therapeutics for effectively managing infectious disease, while minimizing problems associated with microbial resistance. In this revised competing resubmission, two of the largest microbial resistance problems of concern to public health are addressed: first, new antibiotics are developed targeting transglycosylase, which assembles the essential and highly conserved carbohydrate backbone of the bacterial cell wall; second, new antiinfluenza agents are developed targeting the influenza coat proteins hemagglutinin and neuraminidase, which are dependent on the recognition of sialoside carbohydrate receptors for infectivity.