Department of Plant Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran.
Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
Microbes Infect. 2016 Jun;18(6):421-429. doi: 10.1016/j.micinf.2016.03.001. Epub 2016 Mar 9.
Infectious diarrhoea remains an emerging problem in the world health program. Among diarrheagenic agents, Vibrio cholerae and enterotoxigenic and enterohemorrhagic Escherichia coli are critical enteropathogens. AB5 toxin produced by these bacteria, heat-labile enterotoxin (LT), cholera enterotoxin (CT), and shiga-like cytotoxin (STX) can target the immune system and are subunit vaccine candidates. A chemically-synthesized chimeric construct composed of the binding subunits of these toxins (LTB, STXB, and CTXB) was developed based on bioinformatics studies. The whole chimeric protein (rLSC) and each of the segments (rLTB, rSTXB, and rCTXB) were expressed in a prokaryotic expression system (E. coli), purified, and analysed for their immunogenic properties. The results indicate that these recombinant proteins were effectively able to present appropriate epitopes to an animal model of the immune system which could result in and increase IgG in serum and immune responses that protect against the binding activity of these toxins. The immunological assays revealed that the sera of immunized mice prevented toxins from binding to their specific receptors and neutralized their toxic effects. The proposed construct should be considered as a potent immunogen to prevent toxicity and diarrhoea.
感染性腹泻仍然是世界卫生计划中的一个新问题。在致腹泻病原体中，霍乱弧菌和肠产毒性及肠出血性大肠杆菌是重要的肠道病原体。这些细菌产生的 AB5 毒素、不耐热肠毒素 (LT)、霍乱肠毒素 (CT) 和志贺样细胞毒素 (STX) 可以靶向免疫系统，是亚单位疫苗的候选物。根据生物信息学研究，开发了一种由这些毒素的结合亚基（LTB、STXB 和 CTXB）组成的化学合成嵌合构建体。整个嵌合蛋白（rLSC）和各个片段（rLTB、rSTXB 和 rCTXB）均在原核表达系统（大肠杆菌）中表达、纯化，并分析其免疫原性。结果表明，这些重组蛋白能够有效地向免疫系统的动物模型呈现适当的表位，从而增加血清中的 IgG 并产生免疫反应，以防止这些毒素的结合活性。免疫测定显示，免疫小鼠的血清可防止毒素与其特定受体结合，并中和其毒性作用。该构建体可被视为一种有效的免疫原，以预防毒性和腹泻。
