Laboratorio de Patogénesis e Inmunología de Procesos Infecciosos, Instituto de Medicina Experimental, Consejo Nacional de Investigaciones Cientificas y Tecnicas, Academia Nacional de Medicina, Buenos Aires C1425AUM, Argentina.
J Immunol. 2013 Sep 1;191(5):2403-11. doi: 10.4049/jimmunol.1300999. Epub 2013 Aug 5.
The striking feature of enterohemorrhagic Escherichia coli (EHEC) infections is the production of Shiga toxins (Stx) implicated in the development of the life-threatening hemolytic uremic syndrome. Despite the magnitude of the social impact of EHEC infections, no licensed vaccine or effective therapy is available for human use. One of the biggest challenges is to develop an effective and safe immunogen to ensure nontoxicity, as well as a strong input to the immune system to induce long-lasting, high-affinity Abs with anti-Stx-neutralizing capacity. The enzyme lumazine synthase from Brucella spp. (BLS) is a highly stable dimer of pentamers and a scaffold with enormous plasticity on which to display foreign Ags. Taking into account the advantages of BLS and the potential capacity of the B subunit of Stx2 to induce Abs that prevent Stx2 toxicity by blocking its entrance into the host cells, we engineered a new immunogen by inserting the B subunit of Stx2 at the amino termini of BLS. The resulting chimera demonstrated a strong capacity to induce a long-lasting humoral immune response in mice. The chimera induced Abs with high neutralizing capacity for Stx2 and its variants. Moreover, immunized mice were completely protected against i.v. Stx2 challenge, and weaned mice receiving an oral challenge with EHEC were completely protected by the transference of immune sera. We conclude that this novel immunogen represents a promising candidate for vaccine or Ab development with preventive or therapeutic ends, for use in hemolytic uremic syndrome-endemic areas or during future outbreaks caused by pathogenic strains of Stx-producing E. coli.
产志贺毒素（Stx）的肠出血性大肠杆菌（EHEC）感染的显著特征是产生志贺毒素（Stx），这与危及生命的溶血性尿毒症综合征的发展有关。尽管 EHEC 感染的社会影响巨大，但目前尚无针对人类使用的许可疫苗或有效疗法。最大的挑战之一是开发有效的、安全的免疫原，以确保无毒性，以及为免疫系统提供强大的输入，以诱导具有抗 Stx 中和能力的长效、高亲和力 Abs。来自布鲁氏菌属（Brucella spp.）的光氨酸合酶（BLS）是五聚体的高度稳定二聚体，是一种具有巨大可塑性的支架，可以在其上展示外来抗原。考虑到 BLS 的优势以及 Stx2 的 B 亚基诱导 Abs 的潜在能力，这些 Abs 通过阻止 Stx2 进入宿主细胞来防止 Stx2 毒性，我们通过将 Stx2 的 B 亚基插入 BLS 的氨基末端来设计一种新的免疫原。结果表明，该嵌合体具有在小鼠中诱导持久体液免疫反应的强大能力。嵌合体诱导的 Abs 对 Stx2 及其变体具有高中和能力。此外，免疫小鼠完全免受静脉内 Stx2 攻击的保护，接受 EHEC 口服攻击的断奶小鼠通过转移免疫血清完全受到保护。我们得出结论，这种新型免疫原代表了具有预防或治疗目的的疫苗或 Ab 开发的有前途的候选物，可用于溶血性尿毒症综合征流行地区或未来由产 Stx 大肠杆菌的致病性菌株引起的爆发。
