Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur 208016, Uttar Pradesh, India.
The Mehta Family Centre for Engineering in Medicine, Indian Institute of Technology Kanpur, Kanpur 208016, Uttar Pradesh, India.
ACS Infect Dis. 2021 Dec 10;7(12):3182-3196. doi: 10.1021/acsinfecdis.1c00345. Epub 2021 Nov 4.
With the acquirement of antibiotic resistance, has resulted in multiple epidemics of shigellosis, an infectious diarrheal disease, causing thousands of deaths per year. Unfortunately, there are no licensed vaccines, primarily due to low or serotype-specific immunogenicity. Thus, conserved subunit vaccines utilizing recombinant invasion plasmid antigens (Ipa) have been explored as cross-protective vaccine candidates. However, achieving cross-protection against 1, which caused multiple pandemics/epidemics in the recent past, has been difficult. Therefore, a rational approach to improve cross-protection in the preparation for a possible pandemic should involve conserved proteins from 1 (Sd1). IpaC is one such conserved immunogenic protein that is less explored as an independent vaccine due to its instability/aggregation. Therefore, to improve cross-protection and potential immunogenicity and to be prepared for a future epidemic/pandemic, herein, we stabilized recombinant Sd1 IpaC, expressed without its chaperone, using a previously reported stabilizing detergent (LDAO) in a modified protocol and assessed its vaccine potential without an adjuvant. The protein assembled into heterogeneous complex spherical structures in the presence of LDAO and showed improved stability at storage temperatures of -80, -20, 4, 25, and 37 °C while providing enhanced yield and concentration. The protein could also be stably lyophilized and reconstituted, increasing the convenience of transportation and storage. Upon intranasal administration in BALB/c mice, the stabilized-IpaC-immunized groups generated significant antibody response and were not only protected against a high intraperitoneal dose of homologous 1 but also showed 100% survival against heterologous 2a without an adjuvant, while the control animals showed visible diarrhea (bloody-Sd1 challenge), lethargy, and weight loss with 0% survival. Overall, this work demonstrates that stabilized IpaC can be explored as a minimalist, self-adjuvanting, cross-protective, intranasal, single-antigen vaccine.
随着抗生素耐药性的出现，志贺氏菌病（一种传染性腹泻病）已经导致了多次流行，每年造成数千人死亡。不幸的是，目前还没有许可的疫苗，主要是因为免疫原性低或血清型特异性。因此，利用重组侵袭质粒抗原（Ipa）的保守亚单位疫苗已被探索作为交叉保护疫苗候选物。然而，针对导致过去多次大流行/流行的 1 型志贺氏菌，实现交叉保护一直很困难。因此，为可能的大流行做准备的合理方法应该包括从 1 型志贺氏菌（Sd1）中获得保守蛋白。IpaC 是一种保守的免疫原性蛋白，由于其不稳定性/聚集性，作为一种独立的疫苗尚未得到充分探索。因此，为了提高交叉保护作用和潜在的免疫原性，并为未来的流行/大流行做好准备，我们使用以前报道的稳定化清洁剂（LDAO）在改良的方案中稳定了无伴侣蛋白表达的重组 Sd1 IpaC，并在没有佐剂的情况下评估了其疫苗潜力。该蛋白在 LDAO 的存在下组装成异质复杂的球形结构，在 -80、-20、4、25 和 37°C 的储存温度下显示出改善的稳定性，同时提供了更高的产量和浓度。该蛋白还可以稳定地冻干和重构，增加了运输和储存的便利性。在 BALB/c 小鼠中经鼻腔给药后，稳定化 IpaC 免疫组产生了显著的抗体反应，不仅能抵抗同源 1 型的高腹腔剂量，而且在没有佐剂的情况下，对异源 2a 型的保护率达到 100%，而对照组动物出现明显的腹泻（Sd1 攻毒）、昏睡和体重减轻，保护率为 0%。总的来说，这项工作表明，稳定化的 IpaC 可以作为一种最小化、自佐剂、交叉保护、鼻内、单一抗原疫苗进行探索。
