Cross-Protective Vaccines vs. Emerging Infectious Agents

描述（由申请方提供）：开发针对一种以上菌株的疫苗对于防御生物战剂和新出现的传染病至关重要，因为几种不同菌株的感染可能会超过单一疫苗引起的免疫力，并且致病菌株可能在接种疫苗的个体中发展，使我们目前的疫苗无效。该提案的长期目标是开发安全的疫苗，并赋予针对各种传染性病原体的有效交叉保护性免疫状态。我们和其他人最近已经证实S.缺乏功能性DNA腺嘌呤甲基化酶（Dam）的鼠伤寒沙门氏菌的毒力显著减弱，并引发针对亲本dam+菌株攻击的有效保护性免疫状态。(AIM 1）我们计划评估S.鼠伤寒沙门氏菌影响幼稚宿主的先天防御，以及它们如何影响专职抗原呈递细胞将抗原呈递给幼稚CD 4+和CD 8 + T细胞。我们还将分析口服接种沙门氏菌的aroA、dam、aroA dam、Dam过量生产（DamOP）或aroA DamOP突变体是否有效。鼠伤寒沙门氏菌将在未处理宿主中诱导持久的细胞介导的和体液免疫应答的存在，包括系统性的和在粘膜表面的。(AIM 2）治疗指数，或治疗效果与毒性的比率，决定了基于沙门氏菌的疫苗的成功。目前，最有希望的候选者包括在其产物参与关键生物合成途径的基因（aroA aroD）、调节基因（cya crp和phoP phoQ）和编码应激蛋白的基因（htrA）中具有突变的菌株以及这些突变的组合。在这里，我们建议评估dam突变株与一种或多种减毒突变相结合的安全性和有效性。(AIM 3）单次口服免疫dam-或DamOP S.鼠伤寒杆菌在鼠伤寒和禽伤寒模型中对一种以上的沙门氏菌菌株产生显著但不完全的交叉保护性免疫。我们建议确定是否多次免疫大坝或DamOP突变体，单独和组合，可以赋予强大的交叉保护性免疫反应，对多个沙门氏菌临床分离株。(AIM 4）由沙门氏菌dam突变株引起的增强的免疫性提高了来自微生物感染因子的乘客抗原在由dam突变疫苗表达时将引起针对同源病原体的保护性免疫应答的可能性。我们将集中在LcrV乘客抗原从假结核耶尔森氏菌，因为它是一个已知的免疫原，和一个毒力因子所需的分泌效应蛋白进入靶细胞和引发的促抑制反应。我们建议表示Y。pseudotuberculosis LcrV在沙门氏菌dam突变疫苗中的作用，并测试接种疫苗的动物是否对Y.在耶尔森氏菌菌血症的小鼠模型中的假结核感染。

DESCRIPTION (provided by applicant): The development of vaccines that protect against more than one strain is paramount to the defense against biowarfare agents and emerging infectious diseases as infection with several different strains may override the immunity elicited by a single vaccine, and pathogenic strains can develop in vaccinated individuals that make our current vaccines ineffective. The long-range objective of this proposal is to develop vaccines that are safe, and confer a potent state of cross-protective immunity against a variety of infectious agents. It has recently been established by us and others that S. typhimurium lacking a functional DNA adenine methylase (Dam) are significantly attenuated for virulence and elicit a potent state of protective immunity against challenge with the parental dam+ strain. (AIM 1) We plan to evaluate how attenuated strains of S. typhimurium influence innate defenses of naive hosts, and how they influence professional antigen-presenting cells to present antigens to naive CD4+ and CD8+ T cells. We will also analyze whether oral vaccination with aroA, dam, aroA dam, Dam overproducing (DamOP), or aroA DamOP mutants of S. typhimurium will induce in naive hosts the presence of long lasting cell-mediated and humoral immune responses, both systemically and at the mucosal surfaces. (AIM 2) The therapeutic index, or the ratio of the efficacy of the therapy over the toxicity, determines the success of Salmonella based vaccines. Currently, the most promising candidates include strains harboring mutations in genes whose products are involved in key biosynthetic pathways (aroA aroD), regulatory genes (cya crp and phoP phoQ), and genes encoding stress proteins (htrA) and combinations of these mutations. Here we propose to evaluate the safety and efficacy of dam mutant strains in combination with one or more of these attenuating mutations. (AIM 3) Our data show that a single oral immunization of dam- or DamOP S. typhimurium elicits significant but incomplete cross-protective immunity to more than one Salmonella strain in murine and avian models of typhoid fever. We propose to determine if multiple immunizations of dam- or DamOP mutants, alone and in combination, can confer strong cross-protective immune responses against multiple Salmonella clinical isolates. (AIM 4) The heightened immunity elicited by Salmonella dam mutant strains raises the possibility that passenger antigens from microbial infectious agents, when expressed by dam mutant vaccines, will elicit a protective immune response against the cognate pathogens. We will focus on the LcrV passenger antigen from Yersinia pseudotuberculosis since it is a known immunogen, and a virulence factor required for secretion of effector proteins into target cells and elicitation of pro-inhibitory responses. We propose to express Y. pseudotuberculosis LcrV in Salmonella dam mutant vaccines, and test whether vaccinated animals are protected against Y. pseudotuberculosis infection in a mouse model for Yersinia bacteremia.