Novel Vaccine Strategy for Listeria monocytogenes

单核细胞增多性李斯特菌是一种细胞内细菌病原体，可导致严重的食源性疾病 孕妇、老年人、婴儿和免疫功能受损的个人。单核细胞增多性李氏杆菌感染 在所有报告的食源性疾病中病死率最高。单核细胞增多性李氏杆菌很容易 在标准实验室条件下在宿主细胞外培养，使单核细胞增多性乳杆菌成为显著的 公共健康风险和作为生物武器制剂的重大潜在威胁。动物模型表明， 对单核细胞增多性李斯特菌的保护性免疫是由识别和清除CD8的效应细胞介导的 被感染的宿主细胞。疫苗研究表明，刺激保护性CD8效应细胞 需要用活细菌进行亚临床感染。然而，用毒力细菌对人类进行完全免疫 作为疫苗策略，能够在细胞内复制会对任何人群造成重大的健康风险， 尤其是对于那些天生有感染单核细胞增多性李斯特菌风险的人。我们最近开发了 一种产生复制缺陷细菌疫苗载体的新策略 刺激保护性CD8？效应细胞反应。这项提案的重点是利用这种方法来 生产能够产生保护性CD8效应细胞的非复制型单核细胞增多性李斯特菌疫苗株 回应。在特定目标I中，我们将构建非复制型单核细胞增多性李氏杆菌疫苗载体，以传递 对专职和非专职抗原提呈细胞胞浆的天然细菌抗原的保护作用 (APC)用于内源性加工和MHC I类呈递。在具体目标二中，我们将确定 抗原递送到APC的动力学和有效递送抗原所需的细菌生存能力。在……里面 具体目标三，我们将确定疫苗结构的摄取是否使APC对识别敏感 通过单核细胞增多性乳杆菌特异性效应细胞。在特定的目标IV中，我们将确定抗原特异性 在用复制缺陷疫苗构建物免疫后刺激效应细胞，并且 评估保护性抗李斯特菌免疫的刺激作用。我们的目标是在完成拟议的 研究，将确定一种安全有效的复制缺陷疫苗配方，适用于 临床试验。还预计这些研究将为制定 使用类似的方法针对其他细胞内病原体的复制缺陷疫苗载体。

Listeria monocytogenes is an intracellular bacterial pathogen that causes serious foodborne illness in pregnant women, the elderly, infants and immunocompromised individuals. L. monocytogenes infections have the highest case fatality rate of all reported foodborne illnesses. L. monocytogenes can be easily cultured outside of host cells under standard laboratory conditions, making L. monocytogenes a significant public health risk and a significant potential threat as a biological weapons agent. Animal models show that protective immunity to L. monocytogenes is mediated by CD8 ¿ effector cells that recognize and eliminate infected host cells. Vaccine studies have demonstrated that stimulation of protective CD8 ¿ effector cells requires subclinical infection with live bacteria. However, immunization of humans with virulent bacteria fully capable of intracellular replication imposes a significant health risk to any population as a vaccine strategy, especially for those individuals inherently at risk to L. monocytogenes infection. We have recently developed a novel strategy for the generation of replication-deficient bacterial vaccine vectors that are capable of stimulating protective CD8 ¿ effector cell responses. The focus of this proposal is to utilize this approach to produce non-replicating L. monocytogenes vaccine strains capable of generating protective CD8 ¿ effector cell responses. In Specific Aim I, we will construct non-replicating L. monocytogenes vaccine vectors to deliver protective native bacterial antigens to the cytosol of professional and nonprofessional antigen presenting cells (APC) for endogenous processing and MHC Class I presentation. In Specific Aim II, we will determine the kinetics of antigen delivery to APC and the requirement of bacterial viability for efficient antigen delivery. In Specific Aim III, we will determine whether uptake of the vaccine constructs sensitizes APC for recognition by L. monocytogenes-specific effector cells. In Specific Aim IV, we will determine whether antigen specific effector cells are stimulated following immunization with the replication-deficient vaccine constructs, and assess stimulation of protective antilisterial immunity. Our goal is that following completion of the proposed studies, a safe and effective replication-deficient vaccine formulation will be identified that is suitable for clinical trials. It is also envisioned that these studies will provide a foundation for the development of replication-deficient vaccine vectors against other intracellular pathogens using a similar approach.