An Optimized, Synthetic DNA Vaccine Encoding the Toxin A and Toxin B Receptor Binding Domains of Clostridium difficile Induces Protective Antibody Responses In Vivo
An Optimized, Synthetic DNA Vaccine Encoding the Toxin A and Toxin B Receptor Binding Domains of Clostridium difficile Induces Protective Antibody Responses In Vivo
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DOI：
10.1128/iai.01950-14
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发表时间：
2014-10-01
影响因子：
3.1
通讯作者：
Kutzler, Michele A.
中科院分区：
文献类型：
--
作者：
Baliban, Scott M.;Michael, Amanda;Kutzler, Michele A.
艰难梭菌相关疾病（CDAD）构成了工业化国家医院内腹泻病例的绝大多数，并且由两种分泌毒素--毒素A（TcdA）和毒素B（TcdB）--的作用介导。产生强烈抗毒素抗体反应的患者可以清除C。艰难的感染和保持无病。在TcdA和TcdB的羧基末端受体结合结构域（RBD）内已经发现了关键的毒素中和表位，这已经产生了将RBD开发为可行的疫苗靶标的兴趣。虽然已经研究了许多平台，但很少有数据描述针对CDAD的DNA疫苗接种的潜力。因此，我们创建了高度优化的质粒，其编码来自TcdA和TcdB的RBD，其中任何假定的N-连接的糖基化位点被改变。对小鼠和非人灵长类动物进行肌内免疫，然后进行体内电穿孔，在这些动物模型中，疫苗接种诱导显著水平的抗RBD抗体（血液和粪便）和RBD特异性抗体分泌细胞。进一步的表征表明，免疫小鼠和非人灵长类动物的血清可以检测到来自转染细胞的RBD蛋白，以及在体外细胞毒性测定中中和纯化的毒素。用质粒免疫或给予非人灵长类动物血清的小鼠被保护免于用纯化的TcdA和/或TcdB的致死攻击。此外，免疫小鼠在受到C.来自同源（VPI 10463）和异源流行（UK 1）菌株的艰难梭菌孢子。这些数据证明了基于TcdA/B RBD的DNA疫苗在急性毒素相关和胃内孢子诱导的结肠疾病的临床前模型中的稳健免疫原性和功效。
Clostridium difficile-associated disease (CDAD) constitutes a large majority of nosocomial diarrhea cases in industrialized nations and is mediated by the effects of two secreted toxins, toxin A (TcdA) and toxin B (TcdB). Patients who develop strong antitoxin antibody responses can clear C. difficile infection and remain disease free. Key toxin-neutralizing epitopes have been found within the carboxy-terminal receptor binding domains (RBDs) of TcdA and TcdB, which has generated interest in developing the RBD as a viable vaccine target. While numerous platforms have been studied, very little data describes the potential of DNA vaccination against CDAD. Therefore, we created highly optimized plasmids encoding the RBDs from TcdA and TcdB in which any putative N-linked glycosylation sites were altered. Mice and nonhuman primates were immunized intramuscularly, followed by in vivo electroporation, and in these animal models, vaccination induced significant levels of both anti-RBD antibodies (blood and stool) and RBD-specific antibody-secreting cells. Further characterization revealed that sera from immunized mice and nonhuman primates could detect RBD protein from transfected cells, as well as neutralize purified toxins in an in vitro cytotoxicity assay. Mice that were immunized with plasmids or given nonhuman-primate sera were protected from a lethal challenge with purified TcdA and/or TcdB. Moreover, immunized mice were significantly protected when challenged with C. difficile spores from homologous (VPI 10463) and heterologous, epidemic (UK1) strains. These data demonstrate the robust immunogenicity and efficacy of a TcdA/B RBD-based DNA vaccine in preclinical models of acute toxin-associated and intragastric, spore-induced colonic disease.