B. anthracis:passive immunization with anticapsular mAb

性状（由申请方提供）：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。尽管在炭疽病的发病机制中胶囊的重要作用，免疫反应的胶囊已很少受到关注，PGA抗体的保护作用是未知的。这项提议的总体假设是PGA抗体对炭疽具有保护作用。该研究的目标是生成PGA单克隆抗体（mAb）文库，并在体外和体内评价抗体的特性。在初步研究中，通过PGA与有效的新型B细胞佐剂的组合免疫，在小鼠中产生了强烈的同种型转换（IgG）和亲和力成熟的抗体应答。分泌抗PGA IgG的五个杂交瘤已经在很短的时间内产生，并且具有不同表位特异性的另外的mAb的生产正在进行中。因此，已经证明了在小鼠中产生稳健的抗体应答和产生IgG mAb的可行性。该提案的具体目的是i）产生代表一系列表位特异性的PGA IgG mAb文库，ii）评估mAb与可溶性和囊状PGA结合的免疫化学，iii）产生PGA mAb的IgG亚类转换变体，iv）评估可能预测保护的PGA mAb的体外活性，和v）评价表位特异性和抗体同种型在确定皮肤和吸入性炭疽的鼠模型中的保护作用。靶向胶囊用于疫苗开发或免疫治疗是有吸引力的，因为抗胶囊免疫不会受到抗生素耐药性或对基于毒素的免疫具有耐药性的炭疽毒素的工程改造的损害。所提出的保护效力的测定对于靶向B的主动或被动免疫的任何努力都是至关重要的。炭疽胶囊，并将提供被动免疫作为炭疽暴露前或暴露后免疫疗法的概念证明。

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.