The greatest strides in vaccine delivery over the last decade have come primarily from a new class of nanoparticulate antigen carrier that focuses on reverse-engineering the pathogen-immune cell interaction on the molecular level. Such “pathogen-like particles”, or PLPs, take an elegant approach to biomimicry, attempting to artificially isolate or recreate a pathogen’s natural ability to stimulate a targeted immune response. In this work, we focused on the transformation of the probiotic E. coli strain Nissle 1917 into an outer membrane vesicle (OMV) platform for TH1-biasing delivery of a variety of recombinant antigens. We hypothesize that by harnessing the natural immunomodulation of the Nissle 1917 (EcN) bacterium, and pairing this immunomodulation with appropriate vaccine targets that require potent TH1-biasing vaccine responses, we can engineer a recombinant antigen delivery platform that uniquely enhances antigen-specific immunity through pathogen-mimetic vaccination. As bionanoparticulate PLPs often suffer from requiring multiple boosts and external adjuvants to achieve pathogen-mimetic memory responses, we further enhanced our EcN OMV platform with controlled release delivery using injectable polymeric microspheres as a transient OMV depot.
From the immunological characterization of free and encapsulated EcN OMVs’ vaccine capability, two vaccine targets were chosen to demonstrate the efficacy of the OMVs as a PLP platform for vaccine delivery. To test the capacity of the OMVs to functionally display and vaccinate against a heterologous antigen of viral origin, OMVs expressing a subunit of H1N1 hemagglutinin were produced and tested on BALB/c mice. Not only did the resulting immunological assays for vaccine response show great promise for a protective response, generating a 2.6-fold increase in IgG2a:IgG1 titers and a 8.1-fold increase in IFN-γ:IL-4 T-cell secretion versus a gold-standard control, but further analysis using hemagglutination-inhibition assays demonstrated >50-fold enhancement in cross-strain protection against H3N2. Secondly, to test EcN OMVs’ capacity to direct unique immunomodulation to less standard vaccine targets, OMVs expressing the peanut allergen Arah2 were produced as both a prophylactic vaccine (for preventing peanut allergy) and an immunotherapy (for treating extent peanut allergy). Using a BALB/c mouse model for peanut allergy sensitization, a free EcN OMV vaccine dose was administered prior to sensitization, which following anaphylactic challenge post-sensitization resulted in protective survival of 100% of vaccinated mice. Encapsulated controlled release of lower doses of the Arah2-displaying EcN OMVs administered following sensitization were also successful at protecting >50% of mice from some level of anaphylaxis post-challenge while minimizing side-effects relative to traditional sublingual immunotherapy.
The engineering and in vitro/in vivo testing of EcN OMVs as vaccine antigen carriers demonstrated promising efficacy as a pathogen-mimetic platform for protective immunomodulation. Successful testing with a variety of recombinant antigens provides the foundation upon which further development of the EcN OMV platform can lead to a promising host of PLP vaccines.
|Commitee:||Chang, Yung-Fu, DeLisa, Matthew, Shuler, Michael|
|School Location:||United States -- New York|
|Source:||DAI-B 75/11(E), Dissertation Abstracts International|
|Subjects:||Microbiology, Biomedical engineering, Immunology|
|Keywords:||Bionanoparticles, Outer membrane vesicles, Pathogen-like particles, Probiotic bacteria, Recombinant vaccines, Vaccine engineering|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be