Bacteriophage in the Prevention/Diagnosis/Treatment

噬菌体疗法。自世纪初首次发现噬菌体以来，噬菌体已被用于临床应用。然而，它们从未受到严格审查-在确定治疗剂的功效和药代动力学方面-而这是对上市药品实行认证的国家所要求的。这种缺陷有许多历史原因，包括抗生素的发现。然而，在过去的50年中，通过在分子细节上获得关于噬菌体的遗传学和生理学的知识，已经大大增强了目前将噬菌体开发成可靠的抗菌剂的努力。鉴于抗药性细菌的出现，这些努力将是重要的。 λ噬菌体主要衣壳蛋白中的单个氨基酸取代足以赋予保留在哺乳动物循环系统中的能力。解释噬菌体治疗临床失败的建议包括噬菌体与免疫系统的相互作用1。然而，在无菌小鼠的实验中，没有可检测到的针对λ噬菌体的适应性免疫系统抗体，发现小鼠循环系统中的噬菌体滴度在腹膜内（i. p.）静脉内或口服噬菌体施用2.基于这些观察结果，使用连续传代技术选择λ噬菌体突变体，其在腹膜内注射后24小时保留在Balb/C小鼠循环系统中的能力大13，000至16，000倍3。这些“长循环λ噬菌体，称为λ噬菌体，至少有三个突变，包括一个在主要的噬菌体衣壳（E）蛋白中，后者导致残基158处的谷氨酸变为赖氨酸。在目前的实验中，我们证明了E蛋白中的这种特异性取代足以赋予野生型λ噬菌体完整的“长循环”表型。这种重组λ Argo噬菌体，通过制造商拯救，与单一的E158 K取代和其同基因亲本野生型菌株将提供指导，更有效的抗菌治疗噬菌体菌株的发展，他们可能是有用的先天免疫系统的研究。

Bacteriophage therapy. Bacteriophage (phage) have been used for clinical applications since their initial discovery at the beginning of the twentieth century. However, they have never been subjected to the scrutiny--in terms of the determination of efficacy and pharmacokinetics of therapeutic agents--that is required in countries that enforce certification for marketed pharmaceuticals. There are a number of historical reasons for this deficiency, including the overshadowing discovery of the antibiotics. Nevertheless, present efforts to develop phage into reliable antibacterial agents have been substantially enhanced by knowledge gained concerning the genetics and physiology of phage in molecular detail during the past 50 years. Such efforts will be of importance given the emergence of antibiotic-resistant bacteria. Single amino acid substitution in a lambda phage major capsid protein is sufficient to confer a capacity to remain in a mammalian circulatory system. Proposals to explain clinical failures of phage therapy include the interactions of phage with the immune system1. However, in experiments with germ free mice, with no detectable adaptive immune system antibodies to lambda phage, phage titers in the circulatory system of mice were found to decrease exponentially by more than 109pfu within 48 hours of intraperitoneal (i.p.), intravenous or oral phage administration2. Based on these observations, lambda phage mutants were selected, using a serial passage technique, with a 13,000 to 16,000 fold greater capacity to remain in the Balb/C mouse circulatory system 24 hours after i.p. injection3. These "long-circulating lambda phage, called lambda phage, had at least three mutations including one in the major phage capsid (E) protein the latter resulting in the change of a glutamic acid to a lysine at residue 158. In the current experiments we demonstrate that this specific substitution in E protein is sufficient to confer the full "long-circulating" phenotype to wild type lambda phage. This recombinant lambda Argo phage, created by maker rescue, with the single E158K substitution and its isogenic parental wild type strain will provide guidance for the development of more effective antibacterial therapeutic phage strains and they may be useful in studies of the innate immune system.