Translational modifications to improve vaccine efficacy in an oral influenza vaccine

Oral vaccination using protein antigens is complicated by the degradative effects of the inhospitable conditions in the gastrointestinal tract, such as low pH and digestive enzymes, nescessitating protection and effective delivery of the antigen. The bilosome is a lipid-based, vesicle delivery system incorporating bile salts, which is believed to protect the antigen from degradation, and has been shown to induce significant antibody responses when delivered orally with various vaccines. In translational research, from laboratory bench to industrial scale-up, it is necessary to optimise the manufacturing process in order to improve efficiency and simplify production, giving a more economical end-product. In this study we tested two simplified production methods (3-step and 1-step) along with two different storage methods (lyophilised and non-lyophilised), as well as looking at the effect of buffer pH. The formulations were assessed in a murine system for immunogenicity, alongside characterisation in terms of size and antigen entrapment, with the stability of these aspects assessed with respect to time. Both lyophilised and non-lyophilised 3-step formulations induced significant IgG1, IgG2a and IgA titres, with the lyophilised version showing stable size and antigen entrapment up to 9 months.