Integrated Biotherapeutics Inc., Rockville, MD 20850, USA.
Toxins (Basel). 2019 Jun 14;11(6):339. doi: 10.3390/toxins11060339.
(SA) infections cause high mortality and morbidity in humans. Being central to its pathogenesis, thwarts the host defense by secreting a myriad of virulence factors, including bicomponent, pore-forming leukotoxins. While all vaccine development efforts that aimed at achieving opsonophagocytic killing have failed, targeting virulence by toxoid vaccines represents a novel approach to preventing mortality and morbidity that are caused by SA. The recently discovered leukotoxin LukAB kills human phagocytes and monocytes and it is present in all known clinical isolates. While using a structure-guided approach, we generated a library of mutations that targeted functional domains within the LukAB heterodimer to identify attenuated toxoids as potential vaccine candidates. The mutants were evaluated based on expression, solubility, yield, biophysical properties, cytotoxicity, and immunogenicity, and several fully attenuated LukAB toxoids that were capable of eliciting high neutralizing antibody titers were identified. Rabbit polyclonal antibodies against the lead toxoid candidate provided potent neutralization of LukAB. While the neutralization of LukAB alone was not sufficient to fully suppress leukotoxicity in supernatants of USA300 isolates, a combination of antibodies against LukAB, α-toxin, and Panton-Valentine leukocidin completely neutralized the cytotoxicity of these strains. These data strongly support the inclusion of LukAB toxoids in a multivalent toxoid vaccine for the prevention of disease.
（金黄色葡萄球菌）感染会导致人类高死亡率和高发病率。金黄色葡萄球菌通过分泌大量毒力因子，包括双组分、形成孔的白细胞毒素，来破坏宿主防御，这是其发病机制的核心。虽然所有旨在实现调理吞噬杀伤的疫苗开发努力都失败了，但通过类毒素疫苗靶向毒力是预防金黄色葡萄球菌引起的死亡率和发病率的一种新方法。最近发现的白细胞毒素 LukAB 会杀死人类吞噬细胞和单核细胞，并且存在于所有已知的临床分离株中。我们使用基于结构的方法，针对 LukAB 异二聚体的功能域生成了一个突变文库，以鉴定出减毒的类毒素作为潜在的疫苗候选物。根据表达、可溶性、产量、生物物理特性、细胞毒性和免疫原性对突变体进行了评估，并鉴定出了几种能够引起高中和抗体滴度的完全减毒 LukAB 类毒素。针对领先类毒素候选物的兔多克隆抗体提供了对 LukAB 的有效中和作用。虽然 LukAB 的中和作用本身不足以完全抑制 USA300 分离株上清液中的白细胞毒素活性，但针对 LukAB、α-毒素和潘顿-瓦伦丁白细胞毒素的抗体组合完全中和了这些菌株的细胞毒性。这些数据有力地支持将 LukAB 类毒素纳入多价类毒素疫苗中，以预防疾病。
