We describe a novel live oral vaccine type. Conceptually, this vaccine is based on a non-lytic, recombinant filamentous bacteriophage that displays an antigen of interest. To provide proof of concept we used the amino-terminal part of a conserved influenza A virus epitope, i.e. matrix protein 2 ectodomain (M2e) residues 2 to 16, as the antigen of interest. Rather than using the phages as purified virus-like particles as a vaccine, these phages were delivered to intestinal Peyer's patches as a live bacterium-phage combination that comprises Escherichia coli cells that conditionally express invasin derived from Yersinia pseudotuberculosis. Invasin-expressing E. coli cells were internalized by mammalian Hep-2 cells in vitro and adhered to mouse intestinal microfold (M) cells ex vivo. Invasin-expressing E. coli cells were permissive for recombinant filamentous bacteriophage f88 that displays M2e and became persistently infected. Oral administration of the live engineered E. coli-invasin-phage combination to mice induced M2e-specific serum IgG antibodies. Mice that had been immunized with invasin-expressing E. coli cells that carried M2e2-16 displaying fd phages seroconverted to M2e and showed partial protection against challenge with influenza A virus. Oral delivery of a live vaccine comprising a bacterial host that is targeted to Peyer's patches and is persistently infected with an antigen-displaying phage, can thus be exploited as an oral vaccine.

我们描述了一种新型的口服活疫苗类型。从概念上讲，这种疫苗基于展示目的抗原的非裂解重组丝状噬菌体。为了提供概念证明，我们使用了保守的甲型流感病毒抗原决定簇的氨基末端部分，即基质蛋白2胞外域（M2e）残基2至16，作为目标抗原。这些噬菌体不是将噬菌体作为纯化的病毒样颗粒用作疫苗，而是作为活细菌噬菌体组合递送到肠道Peyer斑块中，该活菌噬菌体组合包含有条件表达源自假结核耶尔森氏菌的入侵素的大肠杆菌细胞。体外，哺乳动物Hep-2细胞将表达侵袭素的大肠杆菌细胞内化并离体粘附于小鼠肠道微折叠（M）细胞。表达侵染素的大肠杆菌细胞允许展示M2e并持续感染的重组丝状噬菌体f88。将活体工程化的大肠杆菌-侵袭素-噬菌体组合口服给予小鼠诱导的M2e特异性血清IgG抗体。已经用表达invasin的大肠杆菌细胞免疫的小鼠携带了M2e2-16，它们展示的fd噬菌体血清转化为M2e，并表现出部分针对甲型流感病毒攻击的保护作用。因此可以将包含靶向Peyer氏斑并持续被展示抗原的噬菌体感染的细菌宿主的活疫苗的口服递送用作口服疫苗。