Discovery of Novel Leptospirosis Vaccine Candidates Using Reverse and Structural Vaccinology.
Discovery of Novel Leptospirosis Vaccine Candidates Using Reverse and Structural Vaccinology.
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DOI：
10.3389/fimmu.2017.00463
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发表时间：
2017
影响因子：
7.3
通讯作者：
McBride AJA
中科院分区：
文献类型：
--
作者：
Grassmann AA;Kremer FS;Dos Santos JC;Souza JD;Pinto LDS;McBride AJA
钩端螺旋体是感染哺乳动物的双胚层（两层膜）细菌，引起钩端螺旋体病，这是一个具有全球影响的公共卫生问题。每年有成千上万的人死于钩端螺旋体病，特别是在热带气候的发展中国家。由于多种因素，包括大量无症状的宿主传播细菌，卫生条件差，贫民窟居民人数增加以及缺乏有效的疫苗，预防是困难的。评价了几种钩端螺旋体重组抗原作为灭活疫苗（抗毒素）的替代品;然而，成功有限。一种有前景的候选疫苗可能是一种表面相关蛋白，它可以刺激宿主免疫反应，从血液和器官中清除钩端螺旋体。在这项研究中，一个全面的生物信息学方法的基础上，反向和结构疫苗学应用于发现新的钩体疫苗候选人。对问号钩端螺旋体（Leptospira interrogans serovar Copenhageni）L1-130株基因组进行计算机模拟挖掘，以增强对保守的β-桶（βB）跨膜蛋白和外膜（OM）脂蛋白的鉴定。在另外20种钩端螺旋体属的基因组中筛选了潜在候选疫苗的直系同源物。为每个表面暴露的蛋白质创建具有高度置信度的三维结构模型。主要组织相容性复合体II（MHC-II）的表位进行了鉴定，其位置被映射的结构模型。共鉴定出18种βB跨膜蛋白和8种OM脂蛋白。这些蛋白质在致病性钩端螺旋体属中是保守的。并且被预测具有MHC-II受体的几种变体的表位。对这些表面蛋白序列的结构和功能分析表明，大多数βB跨膜蛋白似乎是与转运相关的TonB依赖性受体。鉴定的其他蛋白质包括，例如，TolC外排泵蛋白，βB跨膜蛋白组装机制的BamA样OM组分，以及LptD样LPS组装蛋白。免疫显性表位的结构定位确定了每种候选疫苗的保守、表面暴露、免疫原性区域的位置。本研究中鉴定的蛋白质目前正在评估其参与毒力，疾病发病机制和生理学以及疫苗开发的实验证据。
Leptospira spp. are diderm (two membranes) bacteria that infect mammals causing leptospirosis, a public health problem with global implications. Thousands of people die every year due to leptospirosis, especially in developing countries with tropical climates. Prophylaxis is difficult due to multiple factors, including the large number of asymptomatic hosts that transmit the bacteria, poor sanitation, increasing numbers of slum dwellers, and the lack of an effective vaccine. Several leptospiral recombinant antigens were evaluated as a replacement for the inactivated (bacterin) vaccine; however, success has been limited. A prospective vaccine candidate is likely to be a surface-related protein that can stimulate the host immune response to clear leptospires from blood and organs. In this study, a comprehensive bioinformatics approach based on reverse and structural vaccinology was applied toward the discovery of novel leptospiral vaccine candidates. The Leptospira interrogans serovar Copenhageni strain L1-130 genome was mined in silico for the enhanced identification of conserved β-barrel (βb) transmembrane proteins and outer membrane (OM) lipoproteins. Orthologs of the prospective vaccine candidates were screened in the genomes of 20 additional Leptospira spp. Three-dimensional structural models, with a high degree of confidence, were created for each of the surface-exposed proteins. Major histocompatibility complex II (MHC-II) epitopes were identified, and their locations were mapped on the structural models. A total of 18 βb transmembrane proteins and 8 OM lipoproteins were identified. These proteins were conserved among the pathogenic Leptospira spp. and were predicted to have epitopes for several variants of MHC-II receptors. A structural and functional analysis of the sequence of these surface proteins demonstrated that most βb transmembrane proteins seem to be TonB-dependent receptors associated with transportation. Other proteins identified included, e.g., TolC efflux pump proteins, a BamA-like OM component of the βb transmembrane protein assembly machinery, and the LptD-like LPS assembly protein. The structural mapping of the immunodominant epitopes identified the location of conserved, surface-exposed, immunogenic regions for each vaccine candidate. The proteins identified in this study are currently being evaluated for experimental evidence for their involvement in virulence, disease pathogenesis, and physiology, in addition to vaccine development.