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Updated: Mar 7, 2026
Intranasal Administration of Recombinant Influenza Vaccines in Chimeric Mouse Models to Study Mucosal Immunity
Published on: June 25, 2015
Safe Recombinant Outer Membrane Vesicles that Display M2e Elicit Heterologous Influenza Protection
Hannah C Watkins1, C Garrett Rappazzo1, Jaclyn S Higgins2
1Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
Abstract:
Recombinant, Escherichia coli-derived outer membrane vesicles (rOMVs), which display heterologous protein subunits, have potential as a vaccine adjuvant platform. One drawback to rOMVs is their lipopolysaccharide (LPS) content, limiting their translatability to the clinic due to potential adverse effects. Here, we explore a unique rOMV construct with structurally remodeled lipids containing only the lipid IVa portion of LPS, which does not stimulate human TLR4. The rOMVs are derived from a genetically engineered B strain of E. coli, ClearColi, which produces lipid IVa, and which was further engineered in our laboratory to hypervesiculate and make rOMVs. We report that rOMVs derived from this lipid IVa strain have substantially attenuated pyrogenicity yet retain high levels of immunogenicity, promote dendritic cell maturation, and generate a balanced Th1/Th2 humoral response. Additionally, an influenza A virus matrix 2 protein-based antigen displayed on these rOMVs resulted in 100% survival against a lethal challenge with two influenza A virus strains (H1N1 and H3N2) in mice with different genetic backgrounds (BALB/c, C57BL/6, and DBA/2J). Additionally, a two-log reduction of lung viral titer was achieved in a ferret model of influenza infection with human pandemic H1N1. The rOMVs reported herein represent a potentially safe and simple subunit vaccine delivery platform.
Insights
Engineered outer membrane vesicles (OMVs) with reduced endotoxin show promise as a safe vaccine platform. These novel OMVs maintain strong immunogenicity and provide protection against influenza virus challenges in preclinical models.
Area of Science:
- Microbiology
- Immunology
- Vaccine Development
Background:
- Recombinant outer membrane vesicles (rOMVs) derived from Escherichia coli are a promising vaccine adjuvant platform.
- High lipopolysaccharide (LPS) content in rOMVs can cause adverse effects, limiting clinical use.
- Lipid IVa, a precursor to LPS, does not stimulate human TLR4, offering a potential solution for reduced pyrogenicity.
Purpose of the Study:
- To develop a safer rOMV vaccine platform by reducing LPS content.
- To evaluate the immunogenicity and efficacy of rOMVs engineered to produce only lipid IVa.
- To assess the potential of these modified rOMVs as a subunit vaccine delivery system.
Main Methods:
- Genetically engineered E. coli (ClearColi strain) to produce lipid IVa and hypervesiculate rOMVs.
- Characterized rOMVs for pyrogenicity, immunogenicity, and ability to promote dendritic cell maturation.
- Developed an influenza A virus matrix 2 protein-based antigen displayed on rOMVs.
- Tested vaccine efficacy in mouse models with different genetic backgrounds and in a ferret model of influenza.
Main Results:
- rOMVs derived from the lipid IVa strain exhibited significantly reduced pyrogenicity while maintaining high immunogenicity.
- These rOMVs promoted dendritic cell maturation and induced a balanced Th1/Th2 humoral response.
- Influenza antigen displayed on rOMVs conferred 100% survival against lethal influenza challenge in mice.
- A two-log reduction in lung viral titer was observed in ferrets infected with pandemic H1N1.
Conclusions:
- Structurally remodeled rOMVs containing only lipid IVa represent a potentially safe and effective subunit vaccine delivery platform.
- This approach overcomes the limitations of traditional rOMVs associated with LPS-induced adverse effects.
- The developed rOMV platform demonstrates significant potential for broad vaccine applications, including against influenza viruses.
