Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, 63110, MO, USA.
Med Microbiol Immunol. 2019 Apr;208(2):185-195. doi: 10.1007/s00430-019-00577-x. Epub 2019 Jan 22.
Bacillus anthracis (BA), the etiological agent of anthrax, secretes protective antigen (PA), lethal factor (LF), and edema factor (EF) as major virulence mediators. Amongst these, PA-based vaccines are most effective for providing immunity against BA, but their low shelf life limits their usage. Previous studies showed that B-cell epitopes, ID II and ID III present in PA domain IV possess higher toxin neutralization activity and elicit higher antibody titer than ID I. Moreover, N-terminal region of both LF and EF harbors PA-binding sites which share 100% identity with each other. Here, in this study, we have developed an epitope-based chimeric vaccine (ID-LFn) comprising ID II-ID III region of PA and N-terminal region of LF. We have also evaluated its protective efficacy as well as stability and found it to be more stable than PA-based vaccine. Binding reactivities of ID-LFn with anti-PA/LF/EF antibodies were determined by ELISA. The stability of chimeric vaccine was assessed using circular dichroism spectroscopy. ID-LFn response was characterized by toxin neutralization, lymphocyte proliferation isotyping and cytokine profiling. The protective efficacy was analyzed by challenging ID-LFn-immunized mice with B. anthracis (pXO1 and pXO2). ID-LFn was found to be significantly stable as compared to PA. Anti-ID-LFn antibodies recognized PA, LF as well as EF. The T-cell response and the protective efficacy of ID-LFn were found to be almost similar to PA. ID-LFn exhibits equal protective efficacy in mice and possesses more stability as compared to PA along with the capability of recognizing PA, LF and EF at the same time. Thus, it can be considered as an improved vaccine against anthrax with better shelf life. ID-LFn, a novel multiepitope chimeric anthrax vaccine: ID-LFn comprises of immunodominant epitopes of domain 4 of PA and N-terminal homologous stretch of LF and EF. The administration of this protein as a vaccine provides protection against anthrax.
炭疽杆菌（BA）是炭疽病的病原体，它分泌保护性抗原（PA）、致死因子（LF）和水肿因子（EF）作为主要的毒力介质。在这些介质中，基于 PA 的疫苗在提供针对 BA 的免疫方面最为有效，但它们的低保质期限制了它们的使用。先前的研究表明，PA 结构域 IV 中的 B 细胞表位 ID II 和 ID III 具有更高的毒素中和活性，并引起更高的抗体滴度比 ID I。此外，LF 和 EF 的 N 端区域都具有与彼此 100%相同的 PA 结合位点。在这里，在这项研究中，我们开发了一种基于表位的嵌合疫苗（ID-LFn），它包含 PA 的 ID II-ID III 区域和 LF 的 N 端区域。我们还评估了它的保护效力以及稳定性，并发现它比基于 PA 的疫苗更稳定。通过 ELISA 测定 ID-LFn 与抗-PA/LF/EF 抗体的结合反应性。通过圆二色性光谱评估嵌合疫苗的稳定性。通过毒素中和、淋巴细胞增殖分型和细胞因子谱分析来表征 ID-LFn 反应。通过用 B. anthracis（pXO1 和 pXO2）对 ID-LFn 免疫的小鼠进行攻毒来分析保护效力。与 PA 相比，ID-LFn 被发现明显更稳定。抗-ID-LFn 抗体识别 PA、LF 和 EF。ID-LFn 的 T 细胞反应和保护效力与 PA 几乎相似。ID-LFn 在小鼠中具有同等的保护效力，并且与 PA 相比具有更高的稳定性，同时具有识别 PA、LF 和 EF 的能力。因此，它可以被认为是一种具有更好保质期的改良炭疽疫苗。ID-LFn，一种新型多表位炭疽嵌合疫苗：ID-LFn 包含 PA 结构域 IV 的免疫显性表位和 LF 和 EF 的 N 端同源片段。该蛋白的给药提供了针对炭疽的保护。
