PGA antigenemia for early diagnosis of anthrax

描述(由申请人提供)：炭疽病治疗的成功关键取决于快速诊断。因此，迫切需要可用于最初会遇到炭疽热的急救人员临床环境中的诊断工具。检测体液中的微生物抗原是诊断传染病的一项行之有效的技术。炭疽芽孢杆菌被由聚γ-D-谷氨酸(PGA)组成的抗吞噬胶囊包围，这增加了PGA免疫检测可以作为炭疽病早期、特异、快速和廉价诊断的手段的可能性。到目前为止，由于PGA的免疫原性差以及完全缺乏关于PGA在体内产生的信息，PGA免疫分析的发展一直受到阻碍。在初步实验中，制备了与PGA反应的高亲和力的单抗，并用于建立PGA的免疫分析方法。该方法具有极高的灵敏度，其下限接近100 pg/ml。该免疫分析方法被用于评估吸入性炭疽病小鼠的PGA抗原血症。结果表明，血液中最初存在可检测到的PGA与可检测到的菌血症的发生是一致的。感染后48h出现大量抗原血症，抗原滴度高达1/500万。提出了六个具体目标：i)确定影响PGA免疫分析性能的免疫化学变量，ii)评估免疫分析在吸入性炭疽小鼠模型中诊断和评估预后及治疗的有效性，iii)评估PGA在体内的组织分布和药代动力学，iv)与私营部门合作开发用于炭疽抗原检测的“潜在最终产品”原型，v)确定基于PGA的炭疽免疫分析的特异性，以及iv)评估PGA免疫分析的有效性，以及IV)非人类灵长类炭疽模型。这是一项转化性研究，有可能极大地影响炭疽病的诊断和治疗。这项研究利用了已有的PGA单抗的库，并优化了一项用于PGA的成熟技术，PGA是迄今为止研究较少的一类微生物抗原。总体目标是生产一种PGA免疫分析原型，可用于最初遇到炭疽热的第一反应者临床环境。

DESCRIPTION (provided by applicant): Success in treatment of anthrax is critically dependent on rapid diagnosis. As a consequence, there is an acute need for diagnostic tools that can be used in a first responder clinical setting where anthrax will be initially encountered. Detection of microbial antigens in body fluids is a proven technology in diagnosis of infectious disease. Bacillus anthracis is surrounded by an anti-phagocytic capsule that is composed of poly-y-D-glutamic acid (PGA), raising the possibility than immunoassay for PGA could be a means for early, specific, rapid and inexpensive diagnosis of anthrax. To date, development of an immunoassay for PGA has been hampered by the poor immunogenicity of PGA and the complete absence of information regarding production of PGA in vivo. In preliminary experiments, high affinity monoclonal antibodies (mAbs) reactive with PGA were produced and used to construct an immunoassay for PGA. The assay has an extraordinarily high sensitivity, with a lower limit near 100 pg/ml. The immunoassay was used to assess PGA antigenemia in a murine model of inhalation anthrax. The results showed that the initial presence of detectable PGA in blood coincided with the occurrence of detectable bacteremia. Full bacteremia was accompanied by a massive antigenemia with antigen titers as high as 1/5,000,000 48 h after infection. Six specific aims are proposed: i) to identify the immunochemical variables that influence the performance of immunoassay for PGA, ii) to evaluate the efficacy of an immunoassay for diagnosis and assessment of prognosis and treatment in a murine model of inhalation anthrax, iii) to assess tissue distribution and pharmacokinetics for clearance of PGA in vivo, iv) to develop, in cooperation with a private sector partner, a prototype "potential ultimate product" for antigen detection in anthrax, v) to determine the specificity of a PGA-based immunoassay for anthrax, and iv) to evaluate the efficacy of PGA immunoassay a non-human primate model of anthrax. This is a translational study that has the potential to dramatically impact diagnosis and treatment of anthrax. The study takes advantage of a library of PGA mAbs that is already in hand and optimizes a proven technology for use with PGA, a heretofore understudied class of microbial antigens. The overall goal is production of a prototype immunoassay for PGA that can be used in a first responder clinical setting where anthrax will be initially encountered.