Development of bacteriophages as alternatives to antibiotics

噬菌体（或噬菌体）是专门感染和杀死细菌的病毒。大多数噬菌体由含有双链DNA基因组的二十面体头部组成，连接到负责粘附宿主细菌表面受体的噬菌体尾部。在感染期间，噬菌体基因组被递送到表达噬菌体蛋白的细胞内部。噬菌体尾/宿主细胞受体界面被认为是生物界中最特异的“锁和钥匙”相互作用之一，并赋予噬菌体对细菌细胞的特异性。对这些机制的分子分析可以深入了解细菌如何击败它们的细菌宿主，并提出人类可以利用来对抗病原菌的成功策略。 自20世纪中期以来，随着化学抗生素在世界范围内的过度使用，我们最近观察到呈现极端抗生素抗性的细菌的数量迅速增加，包括伯克霍尔德氏菌属和寡养单胞菌属的细菌。因此，寻找抗生素的替代品变得越来越重要，并且抗生素的应用或治疗不仅对人类感染，而且对由细菌引起的动物和植物疾病都显示出希望。许多实验研究已经在农业和临床环境中建立了噬菌体治疗功效，最近，在北美已经记录了从病原菌中挽救人类生命的实例。这些结果表明，随着进一步的发展，抗生素将成为补充或取代传统抗生素的有用药物。 本提案的目的是研究噬菌体附着于细菌受体的机制，并利用这些知识，优化用于对抗高度抗生素抗性细菌的噬菌体。为了减少噬菌体抗性的进化，将组合具有不同受体的多个引物，并且靶向毒力因子的引物将促进突变以逃避噬菌体攻击的细菌中的抗毒力。噬菌体可以使用分子生物学进行修饰以消除有问题的基因/蛋白质，并通过添加编码增强活性的蛋白质的基因（例如，扩大宿主范围，穿透生物膜）进行改进。噬菌体受体结合蛋白和细菌表面受体的分子表征将为噬菌体与细菌相互作用机制的本质提供重要的见解。通过这项工作获得的知识将创造机会，为各种新型生物技术应用（包括与农业，工业和医疗保健相关的生物传感器）设计针对致病性和抗生素耐药性细菌的抗生素。

Bacteriophages (or phages) are viruses that specifically infect and kill bacteria. Most phages are comprised of an icosahedral head containing a double-stranded DNA genome, attached to a phage tail responsible for adhering to a surface receptor on the host bacterium. During infection the phage genome is delivered to the cell interior where phage proteins are expressed. The phage tail / host cell receptor interface is thought to be one of the most specific “lock and key” interactions in the biological world, and gives phages their exquisite specificity for bacterial cells. Molecular analysis of these mechanisms can provide insight into how phages defeat their bacterial hosts, and suggest successful strategies man can utilize to combat pathogenic bacteria. With the worldwide overuse of chemical antibiotics since the mid-20th century, we have recently observed a rapid increase in the number of bacteria presenting extreme antibiotic resistance, including bacteria of the genera Burkholderia and Stenotrophomonas. Therefore, the search for alternatives to antibiotics has gained importance, and the application of or treatment with phages has demonstrated promise, not only for human infections, but also for animal and plant diseases caused by bacteria. Numerous experimental studies have established phage treatment efficacy in both agricultural and clinical settings, and recently, instances of human lives being saved from pathogenic bacteria has been documented in North America. These results suggest that with further development, phages will become a useful addition to medicines available to complement or replace traditional antibiotics. The objective of this proposal is to examine phage mechanisms of attachment to bacterial receptors, and with this knowledge, optimize phages for application against highly antibiotic resistant bacteria. To decrease the evolution of phage resistance, multiple phages with different receptors will be combined, and phages that target virulence factors will promote anti-virulence in bacteria mutating to escape phage attack. Phages can be modified using molecular biology to eliminate problematic genes / proteins, and improved by adding genes that encode proteins that enhance activity (e.g. broaden host range, penetrate biofilms). Molecular characterization of the phage receptor-binding proteins, and the bacterium's surface receptors will provide important insights into the nature of the mechanisms involved in phage:bacterium interactions. The knowledge gained through this work will create opportunities to engineer phages against pathogenic and antibiotic resistant bacteria for a variety of novel biotechnological applications, including biosensors, relevant to agriculture, industry, and healthcare.