Schild Stefan, Nelson Eric J, Bishop Anne L, Camilli Andrew
Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
Infect Immun. 2009 Jan;77(1):472-84. doi: 10.1128/IAI.01139-08. Epub 2008 Nov 10.
Outer membrane vesicles (OMVs) offer a new approach for an effective cholera vaccine. We recently demonstrated that immunization of female mice with OMVs induces a long-lasting immune response and results in protection of their neonatal offspring from Vibrio cholerae intestinal colonization. This study investigates the induced protective immunity observed after immunization with OMVs in more detail. Analysis of the stomach contents and sera of the neonates revealed significant amounts of anti-OMV immunoglobulins (Igs). Swapping of litters born to immunized and nonvaccinated control mice allowed us to distinguish between prenatal and neonatal uptakes of Igs. Transfer of Igs to neonates via milk was sufficient for complete protection of the neonates from colonization with V. cholerae, while prenatal transfer alone reduced colonization only. Detection of IgA and IgG1 in the fecal pellets of intranasally immunized adult mice indicates an induced immune response at the mucosal surface in the gastrointestinal tract, which is the site of colonization by V. cholerae. When a protocol with three intranasal immunizations 14 days apart was used, the OMVs proved to be efficacious at doses as low as 0.025 microg per immunization. This is almost equivalent to OMV concentrations found naturally in the supernatants of LB-grown cultures of V. cholerae. Heterologous expression of the periplasmic alkaline phosphatase (PhoA) of Escherichia coli resulted in the incorporation of PhoA into OMVs derived from V. cholerae. Intranasal immunization with OMVs loaded with PhoA induced a specific immune response against this heterologous antigen in mice. The detection of an immune response against this heterologously expressed protein is a promising step toward the potential use of OMVs as antigen delivery vehicles in vaccine design.
外膜囊泡（OMV）为开发有效的霍乱疫苗提供了一种新方法。我们最近证明，用OMV免疫雌性小鼠可诱导持久的免疫反应，并能保护其新生后代免受霍乱弧菌肠道定植。本研究更详细地调查了用OMV免疫后诱导的保护性免疫。对新生儿胃内容物和血清的分析显示存在大量抗OMV免疫球蛋白（Ig）。交换免疫小鼠和未免疫对照小鼠所生的幼崽，使我们能够区分Ig在产前和产后的摄取情况。通过乳汁将Ig转移给新生儿足以使新生儿完全免受霍乱弧菌定植，而仅产前转移则只能减少定植。在经鼻免疫的成年小鼠粪便颗粒中检测到IgA和IgG1，表明在胃肠道黏膜表面诱导了免疫反应，而胃肠道正是霍乱弧菌的定植部位。当采用每14天进行三次经鼻免疫的方案时，OMV在低至每次免疫0.025微克的剂量下就被证明是有效的。这几乎等同于霍乱弧菌LB培养液上清液中天然存在的OMV浓度。大肠杆菌周质碱性磷酸酶（PhoA）的异源表达导致PhoA掺入源自霍乱弧菌的OMV中。用负载PhoA的OMV经鼻免疫可在小鼠中诱导针对这种异源抗原的特异性免疫反应。检测针对这种异源表达蛋白的免疫反应是朝着在疫苗设计中潜在使用OMV作为抗原递送载体迈出的有希望的一步。
