In vivo conjugated multivalent toxoid-polysaccharide vaccine for S. aureus

描述（由申请人提供）：金黄色葡萄球菌是一种革兰氏阳性人类病原体，可引起广泛的感染，从皮肤和软组织感染（SSTI）到危及生命的败血症和肺炎。金黄色葡萄球菌的致病性取决于许多毒力因子，包括细胞表面蛋白和多糖，以及分泌的毒素。其中一组重要的毒素包括溶血素和杀白细胞素等孔隙形成毒素，以及小的肽类毒素，它们对红细胞和白细胞具有溶解活性，特别是对中性粒细胞具有裂解活性，而中性粒细胞是抵抗金黄色葡萄球菌的主要防线。这些毒素引起组织损伤，促进细菌在远处器官的传播和生长，并使病原体逃避宿主的先天免疫反应。此外，已知荚膜多糖（CP）可以保护细菌免受多形核白细胞的吞噬活性，并已被证实是重要的疫苗靶点。综合生物疗法公司（IBT）正致力于开发毒素疫苗联合CPs对抗金黄色葡萄球菌感染。孔隙形成？-溶血素（Hla），又称？-毒素（AT），几乎所有菌株都产生，与几种金黄色葡萄球菌侵袭性疾病有关。最近在金黄色葡萄球菌菌血症患者中进行的微生物学和血清学研究也显示了-毒素和酚溶性调素（PSM）对金黄色葡萄球菌致病性的重要性。根据我们最近的研究，预先存在的抗Hla，¿-毒素和PSM？3 .显著降低成人金黄色葡萄球菌菌血症败血症的风险。该I期SBIR的目标是评估一种新型糖结合葡萄球菌毒素疫苗的可行性。候选疫苗已被设计成代表Hla (AT62) N端与γ -毒素和PSM - 3融合的关键结构域。我们以前已经证明，AT62疫苗可以预防菌血症和肺炎。本研究利用glyvaxyn公司开发的一种独特而新颖的体内生物偶联技术，将这种杂交类毒素与5型荚膜多糖（CP5）偶联，以证明该生物偶联物的有效性。生物偶联技术涉及大肠杆菌细胞工程，表达弯曲杆菌酶PglB以及金黄色葡萄球菌CP8生物合成所需的基因。PglB将n -连接的CP8链转移到引入这些细胞的疫苗结构中。该新技术是糖缀合疫苗领域的一项重大进展，具有传统化学偶联技术无法比拟的诸多优点。在Specific Aim 1中，将生成三种毒素的融合体，并识别衰减突变并将其纳入融合构建体中。候选疫苗将进行免疫原性测试，然后在Aim 2中产生生物偶联物。在Aim 3中，候选疫苗的保护功效将在代表菌血症/败血症和皮肤和软组织感染的两种主要疾病模型中进行评估。在这项研究成功完成后，我们设想进行II期SBIR，其中将为其他主要的金黄色葡萄球菌荚膜多糖CP8生产类似的生物偶联物，并广泛测试多价疫苗（包括我们小组目前正在开发的其他类毒素疫苗的组合）的功效。最终目标是与大型制药公司建立战略伙伴关系，将候选疫苗过渡到临床开发。

DESCRIPTION (provided by applicant): Staphylococcus aureus is a Gram-positive human pathogen that causes a wide range of infections from skin and soft tissue infections (SSTI) to life threatening sepsis and pneumonia. The pathogenicity of S. aureus is dependent on numerous virulence factors, including cell surface proteins and polysaccharides, as well as secreted toxins. An important group of these toxins includes pore forming toxins such as hemolysins and leukocidins, as well as small peptidic toxins, with lytic activity towards erythrocytes and leukocytes particularly the neutrophils that represent the major line of defense against S. aureus. These toxins cause tissue damage, promote bacterial dissemination and growth in distant organs, and enable the pathogen to evade the host innate immune response. Furthermore, capsular polysaccharide (CP) are known to protect bacteria from phagocytic activity of polymorphonuclear leukocytes and have been validated as important vaccine targets. Integrated BioTherapeutics (IBT) is pursuing development of toxin- based vaccines in combination with CPs against S. aureus infections. The pore-forming ?-hemolysin (Hla), also known as ?-toxin (AT), is produced by nearly all strains and is implicated in several S. aureus invasive diseases. Recent microbiological and serological studies in humans with S. aureus bacteremia also show the importance of ¿-toxin and phenol-soluble modulins (PSM) for S. aureus pathogenicity. Based on our recent study, pre-existing antibodies against Hla, ¿-toxin and PSM?3 significantly reduce the risk of sepsis in adults with S. aureus bacteremia. The goal of this Phase I SBIR is to evaluate the feasibility of a novel glycoconjugate staphylococcal toxin based vaccine. Vaccine candidates have been designed that represent a critical structural domain at the N terminus of Hla (AT62) fused to ¿-toxin and PSM?3. We have shown previously that AT62 vaccine provides protection against bacteremia and pneumonia. This proposal utilizes a unique and novel in vivo bioconjugation technology developed by Glycovaxyn Inc. to conjugate this hybrid toxoid with capsular polysaccharide Type 5 (CP5) as proof of concept of the efficacy of the bioconjugate. The bioconjugation technology involves E. coli cells engineered to express the Campylobacter enzyme PglB as well as the genes required for S. aureus CP8 biosynthesis. PglB transfers N-linked CP8 chains to the vaccine construct introduced into these cells. This novel technology is a major development in glycoconjugate vaccine field with multiple advantages over the conventional chemical conjugation. In the Specific Aim 1 fusions of the three toxins will be generated and attenuating mutations identified and incorporated into the fusion construct. The candidate vaccine will be tested for immunogenicity and then bioconjugates generated in Aim 2. In Aim 3 the protective efficacy of the vaccine candidate will be evaluated in two major disease models representing bacteremia/sepsis and skin and soft tissue infections. Upon successful completion of this proposed research we envision a Phase II SBIR in which similar bioconjugate will be produced for the other major S. aureus capsular polysaccharide CP8 and the efficacy of the multivalent vaccine (including combination other toxoid vaccines currently under development in our group) extensively tested. The ultimate goal is to build a strategic partnership with large pharma to transition the vaccine candidate into clinical development.