PHOP/PHOQ DELETED S TYPHI VACCINE STRAINS

接种疫苗是预防疾病的一种有效而经济的方法， 多价口服疫苗将拥有最广泛的 临床应用。减毒沙门氏菌已经成功 在小鼠模型中作为异源基因传递的活载体的研究 胃肠道免疫系统的抗原。在人类身上的研究已经 是有限的，对人类免疫原性重要的变量 没有明确的定义。一株伤寒沙门氏菌(Ty800)被删除 沙门氏菌的Phop/PhoQ毒力调节基因是非常安全的 在人类志愿者中具有免疫原性，这种菌株已经被改造成 表达临床相关的异源抗原。这项建议 描述了一项旨在评估 使用双价伤寒沙门氏菌的人体疫苗方案 疫苗株。这些研究强调的是合理修改 临床可接受的人类疫苗株和疫苗接种方案 它可能改变异源抗原的免疫原性，如 抗原，抗原在细菌细胞内的位置和作用机制 表达或分泌。使用IRB批准的已建立的人体研究 协议，成年志愿者接种疫苗，遵循安全和 疫苗脱落，并对粘膜的证据进行了密集的评估， 体液和细胞免疫--对伤寒沙门氏菌抗原和 相关异源抗原。序贯口服疫苗接种方案 由表达细胞质的伤寒沙门氏菌疫苗株组成 幽门螺杆菌尿素酶和纯化的重组尿素酶 大肠杆菌不耐热毒素佐剂将在成年志愿者身上进行测试 幽门螺杆菌血清阴性。一株表达融合的伤寒沙门氏菌 大肠埃希氏菌溶血素A与尿素酶B相连的抗原 将对细菌细胞进行研究，以确定分泌物是否改变 这个系统的免疫原性。将生成其他构造 表达大肠杆菌不耐热毒素突变体或大肠杆菌 定植因子抗原(CFA/I)。这些新的菌株将是 在体外进行评估，然后在志愿者身上进行测试，以确定 无论这些具有不同结构或亚细胞结构的分子 位置可引起全身和/或粘膜免疫反应。这些 研究旨在提供新的人类安全性和免疫原性。 对活菌临床发展至关重要的数据 疫苗载体。

Vaccination is an effective and economical method of preventing disease, and multivalent, orally administered vaccines will have the widest clinical application. Attenuated Salmonella have been successfully studied in murine models as live vectors for delivery of heterologous antigens to the gastrointestinal immune system. Studies in humans have been limited, and variables important for immunogenicity in humans have not been clearly defined. A Salmonella typhi strain (Ty800) deleted for the phoP/phoQ virulence regulon of Salmonellae is very safe and immunogenic in human volunteers, and this strain has been modified to express clinically relevant heterologous antigens. This proposal describes a program of translational research designed to evaluate Salmonella-based vaccine regimens in humans utilizing bivalent S. typhi vaccine strains. These studies emphasize rational modification of clinically acceptable human vaccine strains and vaccination regimens which may alter immunogenicity of heterologous antigens such as type of antigen, location of antigen within the bacterial cell and mechanism of expression or secretion. Using an established IRB-approved human study protocol, adult volunteers are vaccinated, followed for safety and vaccine shedding, and intensively evaluated for evidence of mucosal, humoral and cellular immune-responses to both S. typhi antigens and the relevant heterologous antigens. A sequential oral vaccination regimen consisting of a S. typhi vaccine strain expressing cytoplasmic Helicobacter pylori urease followed by purified recombinant urease and E. coli heat labile toxin adjuvant will be tested in adult volunteers seronegative for H. pylori. An S. typhi strain expressing a fusion antigen of E. coli hemolysin A linked to urease B which is secreted from the bacterial cell will be studied to determine whether secretion alters immunogenicity in this system. Additional constructs will be generated which express either an E. coli heat labile toxin mutant or an E. coli colonization factor antigen (CFA/I). These new strains will be evaluated in vitro and subsequently tested in volunteers to determine whether these molecules with different structures or subcellular location can engender systemic and/or mucosal immune responses. These studies are designed to provide novel human safety and immunogenicity data which is vital to the clinical development of live bacterial vaccine vectors.