Ruggiero Alessia, Choi Han-Gyu, Barra Giovanni, Squeglia Flavia, Back Young Woo, Kim Hwa-Jung, Berisio Rita
Institute of Biostructures and Bioimaging, IBB, CNR, Napoli, Italy.
Department of Microbiology and Medical Science, College of Medicine, Chungnam National University, Daejeon, South Korea.
Front Mol Biosci. 2022 Aug 11;9:964645. doi: 10.3389/fmolb.2022.964645. eCollection 2022.
Vaccine development against Tuberculosis is a strong need, given the low efficacy of the sole vaccine hitherto used, the Bacillus Calmette-Guérin (BCG) vaccine. The chaperone-like protein HtpG of is a large dimeric and multi-domain protein with promising antigenic properties. We here used biophysical and biochemical studies to improve our understanding of the structural basis of HtpG functional role and immunogenicity, a precious information to engineer improved antigens. We showed that HtpG is a dimeric nucleotide-binding protein and identified the dimerisation interface on the C-terminal domain of the protein. We also showed that the most immunoreactive regions of the molecule are located on the C-terminal and middle domains of the protein, whereas no role is played by the catalytic N-terminal domain in the elicitation of the immune response. Based on these observations, we experimentally validated our predictions in mice, using a plethora of immunological assays. As an outcome, we designed vaccine antigens with enhanced biophysical properties and ease of production, albeit conserved or enhanced antigenic properties. Our results prove the efficacy of structural vaccinology approaches in improving our understanding of the structural basis of immunogenicity, a precious information to engineer more stable, homogeneous, efficiently produced, and effective vaccine antigens.
鉴于迄今为止唯一使用的疫苗卡介苗（BCG）效力较低，开发抗结核病疫苗的需求十分迫切。结核分枝杆菌的伴侣样蛋白HtpG是一种大型二聚体多结构域蛋白，具有良好的抗原特性。我们在此利用生物物理和生化研究来增进对HtpG功能作用和免疫原性结构基础的理解，这是设计改良抗原的宝贵信息。我们表明HtpG是一种二聚体核苷酸结合蛋白，并确定了该蛋白C末端结构域上的二聚化界面。我们还表明，该分子最具免疫反应性的区域位于蛋白的C末端和中间结构域，而催化性的N末端结构域在引发免疫反应中不起作用。基于这些观察结果，我们通过大量免疫测定在小鼠中实验验证了我们的预测。结果，我们设计出了具有增强的生物物理特性且易于生产的疫苗抗原，同时保留或增强了抗原特性。我们的结果证明了结构疫苗学方法在增进对免疫原性结构基础理解方面的有效性，这是设计更稳定、均一、高效生产且有效的疫苗抗原的宝贵信息。
