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Technologies for Emerging Infectious Diseases

Technologies for Emerging Infectious Diseases - Poster Session E

Poster L3 - Thin Film Formulation of an Outer Membrane Vesicle Vaccine

Saturday, October 26, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Nolan Randall (he/him/his)

Undergraduate Student
Department of Electrical, Computer, and Biomedical Engineering, Union College
Schenectady, New York, United States

Primary Investigator(s)

Stephanie M. Curley, PhD (she/her/hers)

Mary H. '80 and Richard K. Templeton '80 Assistant Professor of Biomedical Engineering
Department of Electrical, Computer, and Biomedical Engineering, Union College
Schenectady, New York, United States

Introduction: Infectious diseases caused by mucosal pathogens continue to pose a threat to humans across the globe. Most recently, the respiratory infection SARS-CoV-2, more commonly known as COVID-19, demonstrated the dangers these pathogens pose to the human body. Lower respiratory infections are currently the fourth leading cause of death in the world. While vaccines are continually developed to combat these pathogens, major advances are primarily being made with injectable vaccinations. Mucosal vaccines provide distinct advantages over traditional injectable vaccinations, as they promote a heightened immune response at the mucosal membrane, which is the main site of pathogen infection.

Outer membrane vesicles (OMVs), shed from gram-negative bacteria, occur naturally at relatively low concentrations. Genetic engineering can be used to enable bacteria to present protein antigens on their outer membrane, which remain on the surface of the vesicle after exocytosis. Ultracentrifugation can then be used to isolate outer membrane vesicles at high concentrations from genetically engineered bacteria, enabling these vesicles to be viable antigen-presenting particles.

Thin films are a promising mucosal vaccine platform, as they can carry a variety of antigens in the form of microparticles or nanoparticles, such as OMVs. Additionally, the salivary environment is extremely effective at dissolving thin films due to a combination of an aqueous environment, temperature, and enzymes.

Materials and

Methods: Films were made in 20 mM Tris, 1 M PBS, and diH2O. Components tested at varying concentrations include HPMC, PVA, sorbitol, glycerol, PEG, and PMAL.

Outer membrane vesicles (OMVs) containing protein antigens were incorporated into each film. To test OMV stability over time, experiments were conducted where films containing OMVs were left covered at room temperature for up to 28 days. The films were then dissolved in various components (described below), and the count of OMVs was analyzed using dynamic light scattering to determine percent recovery.

To test film dissolution, films were dissolved in 1 M PBS, DMEM Cell Media, and enzyme solutions to more accurately replicate saliva. Enzymes tested were alpha-amylase, lingual lipase, and human lysozyme at 20oC and 37oC.

SEM and AFM were used to analyze film roughness, thickness, and surface composition. SEM was used to perform elemental analysis of the film surface, verifying the dispersion of different components throughout the thin film.

Results, Conclusions, and Discussions: A majority of the outer membrane vesicles were recovered from the conducted stability studies. This indicates the potential viability of using a thin film vaccine stored at room temperature containing outer membrane vesicles. As expected, exposure to the enzyme solutions resulted in a faster film breakdown time, which is optimal for use in a mucosal vaccine. An ideal thin film formulation can dissolve in simulated saliva at 37oC in approximately five minutes; our optimal film resulted in a shorter dissolution time than this when exposed to simulated salivary conditions.

SEM and AFM indicated a low surface roughness and homogenous distribution of components throughout the thin film. Overall, a thermostable mucosal thin film vaccine would greatly improve access to vaccinations in all regions of the world as no ultra-low temperature freezers are needed.

Acknowledgements (Optional):