MUCOSAL AND SYSTEMIC IMMUNITY IN HUMAN SHIGELLA VACCINES

疫苗的成功取决于诱导强烈、持久的免疫反应，以保护个体免受随后感染原的侵害。流行病学证据和临床试验结果表明，研制一种有效的志贺氏菌疫苗是一个可以实现的目标。成年志愿者在CVD实验中感染野生型sonnei或S. flexneri 2a，在再次感染同源菌株后，明显免受疾病的侵害。然而，在这些志愿者中检测到的志贺氏菌抗体的存在与挑战后对志贺氏菌病的耐药性无关。细胞介导免疫（CMI）是一种关键的效应机制，参与了对许多细胞内病原体（包括细菌）的保护。然而，关于CMI在志贺氏菌感染中的作用的信息非常有限。拟议研究的总体目标是确定在接种志贺氏菌疫苗和自然感染志贺氏菌后有效保护志贺氏菌病的免疫学机制。我们的假设是，CMI反应在志愿者感染野生型志贺氏菌和活志贺氏菌候选疫苗后保护志愿者免受志贺氏菌病的侵害方面发挥了核心作用。识别与暴露于野生型志贺氏菌后的保护相关的CMI将极大地增强我们对志贺氏菌病保护机制和志贺氏菌疫苗开发的理解。具体来说，使用从粘膜活检中分离的细胞和从接种了福氏沙门氏菌2a、痢疾沙门氏菌和索内沙门氏菌的野生型或减毒株的志愿者身上获得的外周血单个核细胞（PBMC），我们提出验证以下假设：(1)野生型志贺氏菌的攻击或志贺氏菌候选疫苗的免疫可引起循环中特异性细胞毒性T淋巴细胞（CTL）的出现；(2)野生型志贺氏菌挑战或志贺氏菌减毒株免疫引起循环中特异性T淋巴细胞的出现，这些T淋巴细胞增殖并产生干扰素γ干扰素γ (ifn - γ)以及其他“1型”细胞因子，以响应志贺氏菌抗原。(3)野生型志贺氏菌攻击或志贺氏菌减毒株免疫可引起肠道黏膜出现特异性CTL效应物和T淋巴细胞，这些T淋巴细胞增殖并产生IFN- γ，以及其他“1型”细胞因子，以响应志贺氏菌抗原；(4)粘膜和全身水平免疫引起的CTL反应和/或ifn - γ产生与对毒性志贺氏菌菌株攻击的保护相关；(5)确定志贺氏菌抗原中是否能鉴定出“保护性表位”。

The success of vaccines depends upon the induction of strong, long lasting immune responses that will protect the individual from a subsequent encounter with the infectious agent. Epidemiologic evidence and results of clinical trials suggests that the development of an effective vaccine against Shigella is an achievable goal. Adult volunteers who were experimentally infected with either wild type S. sonnei or S. flexneri 2a at the CVD were significantly protected against illness following rechallenge with the homologous strain. However, the presence of antibodies to Shigella measured in these volunteers did not correlate with resistance to shigellosis following challenge. Cell-mediated immunity (CMI) is a key effector mechanism involved in protection against many intracellular pathogens, including bacteria. However, very limited information is available concerning the role of CMI in Shigella infection. The overall goal of the proposed studies is to identify the immunological mechanisms that mediate effective protection from shigellosis following vaccination and natural infection with Shigella. Our hypothesis is that CMI responses play a central role in protection of volunteers from shigellosis following infection with wild-type Shigella and live Shigella vaccine candidates. The identification of CMI that correlate with protection following exposure to wild-type Shigella will greatly enhance our understanding of the mechanisms underlying protection in shigellosis and the development of Shigella vaccines. Specifically, using cells isolated from mucosal biopsies and peripheral blood mononuclear cells (PBMC) obtained from volunteers immunized with wild-type or attenuated strains of S. flexneri 2a, S. dysenteriae and S. sonnei we propose to test the following hypotheses: (1) Challenge with wild-type Shigella or immunization with Shigella vaccine candidates elicits the appearance in circulation of specific cytotoxic T lymphocytes (CTL); (2) Challenge with wild-type Shigella or immunization with attenuated strains of Shigella elicits the appearance in circulation of specific T lymphocytes that proliferate and produce interferon-gamma interferon-gamma (IFN-gamma), as well as other "type-1" cytokines, in response to Shigella antigens, (3) Challenge with wild-type Shigella or immunization with attenuated strains of Shigella elicits the appearance in the gut mucosa of specific CTL effectors and T lymphocytes that proliferate and produce IFN- gamma, as well as other "type-1" cytokines, in response to Shigella antigens; (4) CTL responses and/or IFN-gamma production elicited by immunization at the mucosal and systemic levels correlate with protection to challenge with virulent Shigella strains; and (5) Determine whether "protective epitopes" can be identified in Shigella antigens.