Characterization of Francisella tularensis-specific bacteriophages

噬菌体是一种病毒，它通过破坏细菌的新陈代谢或引起 细菌裂解噬菌体的这些独特性质已被开发作为抗微生物剂超过 100年抗生素耐药性的出现和近年来新抗生素的缺乏， 在抗生素缺乏的临床情况下， 不再有效。这项提议的总体目标是描述一组噬菌体的特征， 进一步被开发为治疗由革兰氏阴性细菌引起的致命性人类疾病土拉菌病的疗法， 土拉弗朗西斯菌Francisella tularensis（Ft.）Ft是一种高度普遍存在的，传染性的，细胞内的细菌，在整个北卡罗来纳州普遍存在。 美国参考由于其武器化的历史，Ft被CDC归类为第1层A类选择剂， 这是一个非常危险的化学品，可能会在几个国家使用，并可能被用作生物恐怖剂。9/11事件后的炭疽粉末袭击 重新激发了人们对Ft研究的医学和科学兴趣。兔热病在美国是一种必须报告的疾病。 自然发生的土拉菌病在除夏威夷外的美国各州均有报道。目前，没有疫苗 可用于兔热病预防。不幸的是，抗生素治疗对严重的 呼吸道土拉菌病，如果在生物恐怖中使用武器化的抗真菌菌株， 攻击会导致疾病爆发总之，这些表明，有效治疗措施的发展 对付这种可怕的生物威胁剂是必要的噬菌体可以提供一个很好的替代， 用于治疗土拉菌病的常规抗生素疗法的附加优点是它们 无毒、自我复制、在感染部位扩增，并且不干扰微生物群。然而，在这方面， 迄今为止，在文献中尚未报道抗弗朗西斯氏菌的噬菌体。作为概念验证，我们 已经从环境样品中分离出一组弗朗西斯菌特异性裂解噬菌体群体。具体目标 1，我们将从这些样品中分离出一组单独的FT特异性引物，并对其进行表征。 它们的遗传、生化和物理特性。在具体目标2中，我们将描述其生物学特性， 特性.具体来说，我们将确定其生长特性，宿主范围和潜在的细胞表面 受体。我们将配制一种Ft特异性噬菌体混合物，并开发检测噬菌体的能力的方法。 鸡尾酒杀死胞内弗朗西斯菌。这是第一个全面的研究，针对的特点， FT特异性噬菌体。针对A类1级选择的FT特异性抗体的分离和表征 Ft SchuS 4试剂和能够杀死细胞内的新的Ft特异性噬菌体混合物的制剂 细菌是这项建议中最具创新性的方面。我们希望拟议的 这些研究将为开发一种新的治疗兔热病的方法铺平道路。 人类

Bacteriophages are viruses that infect and kill bacteria either by disrupting their metabolism or by causing bacterial lysis. These unique properties of bacteriophages have been exploited as antimicrobial agents for over 100 years. The emergence of antibiotic resistance and the lack of introduction of new antibiotics in recent years, has renewed interest in the development of bacteriophage-based therapies in clinical situations where antibiotics are no longer effective. The overall goal of this proposal is to characterize a panel of bacteriophages that could further be developed as a therapy to treat fatal human disease tularemia caused by a Gram-negative bacterium, Francisella tularensis (Ft). Ft is a highly ubiquitous, infectious, intracellular bacterium prevalent throughout North America. Ft is classified as a Tier 1 Category A select agent by the CDC due to its history of weaponization by several countries, and its potential to be used as a bioterror agent. Anthrax powder attacks after 9/11 incidence have renewed the medical and scientific interest in Ft research. Tularemia is a notifiable disease in the USA. Naturally occurring tularemia is reported from all the states of the USA, except Hawaii. Currently, no vaccine is available for tularemia prophylaxis. Unfortunately, antibiotic treatment is not particularly effective against severe respiratory tularemia and may not be effective at all, if a weaponized antibiotic-resistant strain used in a bioterror attack causes an outbreak. Together, these indicate that the development of effective therapeutic measures against this dreaded biothreat agent is necessary. Bacteriophages may provide an excellent alternative to the conventional antibiotic therapy for the treatment of tularemia with the added advantage being that they are innocuous, self-replicating, amplify at the site of infection, and do not perturb microbiota. However, bacteriophages against Francisella have not been reported in the literature to-date. As a proof-of-concept, we have isolated a panel of Francisella-specific lytic phage populations from environmental samples. In specific aim 1 of this proposal, we will isolate a collection of individual Ft-specific phages from these samples and characterize their genetic, biochemical, and physical properties. In specific aim 2, we will characterize their biological properties. Specifically, we will determine their growth characteristics, host-range, and potential cell surface receptors. We will formulate an Ft-specific phage cocktail and develop assays to test the ability of phage cocktail(s) to kill intracellular Francisella. This is a first comprehensive study directed at the characterization of Ft-specific bacteriophages. Isolation and characterization of Ft-specific phages against Category A Tier-1 select agent Ft SchuS4 and formulation of novel Ft-specific bacteriophage cocktail capable of killing intracellular bacteria constitute the most innovative aspects of this proposal. We expect that the outcome of the proposed studies will pave the way for the development of a novel therapeutic approach for the treatment of tularemia in humans.