Novel antigen designs and delivery platforms to enhance the protective ability of Tpr-based vaccines for syphilis

摘要 在过去的二十年里，我们努力开发梅毒疫苗， 在免疫/攻击实验中对梅毒提供高度但不完全保护的抗原， 兔子模型这两种候选疫苗来源于选定成员的保守区域 梅毒螺旋体重复序列（Tpr）抗原TprC/D2和TprK。对这些抗原的免疫力已经被 显示通过调理吞噬作用增强病原体清除，并提供实质性保护， 与对照组相比，激发部位的下疳发展。然而，在这些早期的疫苗设计中， 省略了TprC和TprD 2蛋白的几个预测的表面表位，因为它们显示出与TprD蛋白的表位相同的表位。 有限程度的抗原变异，即使我们证明它们可以提供额外的 病原体调理作用和活化巨噬细胞吞噬作用的靶标，如果与 诱导Th 1型应答的佐剂。 为了获得一种完全保护性的梅毒疫苗，我们的目标是修改我们的早期疫苗设计， TprC和TprD 2蛋白的保护性表位。首先（目的1），我们将评估 全长重组TprC和TprD 2，使用设计为覆盖所有抗原变体的抗原混合物 这些蛋白质，其中也将包含TprK保守片段。同时，我们将进行一系列 TprC和TprD 2的T细胞表位和保护性B细胞表位的实验， 开发用于抗原递送的替代平台，目标是递送选定的表位，而不是 而不是全长抗原。对于这些映射实验（也在目标1中计划），我们将使用TprK作为 对照抗原，因为B-和T-细胞表位已经在过去鉴定了这种蛋白质。代替 重组蛋白，我们将工程和测试嵌合多联体（目标2）和嵌合HPV为基础的 病毒样颗粒（VLP，目标3）。这些替代的递送平台将特异性地诱导免疫， 密螺旋体表面上调理抗体的靶点，并可能增强病原体清除， 传染性挑战在目标4中，我们将联合收割机结合我们的结果和卡梅隆博士（项目1）获得的结果。 与她选择的候选疫苗（Tp 0751）结合，将我们最具保护性的疫苗设计和递送 平台随后，将对我们的FILA疫苗设计进行最终免疫/攻毒实验。 使用现代梅毒分离株评估免疫力的总体保护水平和持久性， 在兔免疫后攻击免疫动物。

ABSTRACT Over the last two decades, our efforts to develop a syphilis vaccine have allowed identification of two antigens that confer high but not complete protection to syphilis in immunization/challenge experiments in the rabbit model. These two vaccine candidates were derived from conserved regions of selected members of the Treponema pallidum repeat (Tpr) antigens TprC/D2 and TprK. Immunity to these antigens has been shown to enhance pathogen clearance by opsonophagocytosis and provide substantial protection from chancre development at challenge sites compared to controls. In these early vaccine designs, however, several predicted surface epitopes of the TprC and TprD2 proteins were omitted because they showed a limited degree of antigenic variation, even though we demonstrated that they could provide additional targets for pathogen opsonization and phagocytosis by activated macrophages if used in combination with adjuvants inducing a Th1-type response. To attain a fully protective syphilis vaccine we aim to modify our early vaccine design to include additional protective epitopes of the TprC and TprD2 proteins. First (Aim 1), we will evaluate the protective activity of full-length recombinant TprC and TprD2 using a cocktail of antigens designed to cover all antigenic variants of these proteins, which will also contain the TprK conserved fragment. In parallel, we will conduct a series of experiments to map T-cell epitopes and protective B-cell epitopes of TprC and TprD2 to inform development of alternative platforms for antigen delivery, with the goal of delivering selected epitopes rather than on full length antigens. For these mapping experiments (also planned in Aim 1), we will use TprK as a control antigen, as B-and T-cell epitopes were already identified for this protein in the past. In lieu of recombinant proteins, we will engineer and test chimeric concatemers (Aim 2) and chimeric HPV-based viral-like particles (VLPs, Aim 3). These alternative delivery platforms will specifically induce immunity to targets of opsonizing antibodies on the treponemal surface, and likely enhance pathogen clearance upon infectious challenge. In Aim 4, we will combine our results and those obtained by Dr. Cameron (Project 1) with her selected vaccine candidate (Tp0751) to combine our most protective vaccine designs and delivery platform. Subsequently, a final immunization/challenge experiment with our fila vaccine design will be performed to assess overall level of protection and durability of immunity using a modern syphilis isolate to challenge immunized animals following rabbit immunization.