B. anthracis:passive immunization with anticapsular mAb

描述(申请人提供)：炭疽杆菌被一个由聚γ-D-谷氨酸(PGA)组成的抗吞噬胶囊包围。尽管胶囊在炭疽的发病机制中起着至关重要的作用，但对胶囊的免疫应答却鲜有人关注，PGA抗体的保护作用尚不清楚。这一提议的总体假设是PGA抗体对炭疽病具有保护作用。这项研究的目标是建立一个PGA单抗(MAbbs)文库，并在体外和体内评估抗体的性质。在初步研究中，通过将PGA与一种有效的新型B细胞佐剂相结合，在小鼠中产生了强大的同型转换(IgG)和亲和力成熟的抗体反应。在很短的时间内已经产生了五个分泌抗PGA抗体的杂交瘤细胞，另外一些具有不同表位特异性的单抗的生产正在进行中。因此，在小鼠中产生强大的抗体反应和生产LGG单抗的可行性已经被证明。该建议的具体目的是：i)建立代表一系列表位特异性的PGA免疫球蛋白单抗文库；ii)评估与可溶性和囊膜PGA结合的单抗的免疫化学；iii)产生PGA单抗的Ig G亚类开关变异体；iv)评估可预测保护作用的PGA单抗的体外活性；以及v)评估表位特异性和抗体亚型在确定皮肤和吸入性炭疽小鼠模型中的保护作用。以胶囊为目标进行疫苗开发或免疫治疗是有吸引力的，因为抗包膜免疫不会因抗生素耐药性或改造抗毒素免疫的炭疽毒素而受到影响。拟议的保护效力的确定是针对炭疽杆菌胶囊的主动或被动免疫的任何努力的核心，并将为被动免疫作为炭疽暴露前或暴露后免疫疗法的概念提供证据。

DESCRIPTION (provided by applicant): Bacillus anthracis is surrounded by an antiphagocytic capsule that is composed of poly-gamma-D-glutamic acid (PGA). Despite an essential role for the capsule in the pathogenesis of anthrax, the immune response to the capsule has received little attention, and the protective role of PGA antibody is unknown. The overall hypothesis for this proposal is that PGA antibodies are protective against anthrax. The goal for the study is to generate a library of PGA monoclonal antibodies (mAbs) and to evaluate the properties of the antibodies in vitro and in vivo. In preliminary studies, a strong isotype-switched (IgG) and affinity-matured antibody response has been generated in mice through immunization with PGA in combination with a potent and novel B-cell adjuvant. Five hybridomas that secrete anti-PGA IgG have been generated in a very short time, and production of additional mAbs having distinct epitope specificities is in progress. Thus, the feasibility for generation of a robust antibody response in mice and for production of lgG mAbs has been demonstrated. The specific aims of the proposal are to i) generate a library of PGA IgG mAbs that represent a spectrum of epitope specificities, ii) evaluate the immunochemistry of mAb binding to soluble and capsular PGA, iii) generate IgG subclass switch variants of PGA mAbs, iv) assess in vitro activities of PGA mAbs that may be predictive of protection, and v) evaluate the role of epitope specificity and antibody isotype in determining protection in murine models of cutaneous and inhalation anthrax. Targeting the capsule for vaccine development or immunotherapy is attractive because anticapsularimmunity would not be compromised by antibiotic resistance or engineering of an anthrax toxin that is resistant to toxin-based immunity. The proposed determination of protective efficacy is central to any effort at active or passive immunization that targets the B. anthracis capsule and would provide proof of concept for passive immunization as a pre- or post-exposure immunotherapy for anthrax.