Stability of S-HBsAg in long-term stored lyophilised plant tissue

A potent plant-derived oral vaccine against Hepatitis B Virus (HBV) requires a durable and compact form for efficacious and convenient distribution and delivery. In the previous study we have devised a successful freeze-drying process of plant material containing the HBV small surface antigen (S-HBsAg) for the purpose of an oral vaccine against the virus, but product storage stability was limited to 4 °C. The aim of this study was to upgrade a freeze-dried product formula to facilitate successful long-term storage of S-HBsAg assembled into Virus-Like Particles (VLPs) at elevated temperatures. Series of additional excipients and storage conditions were tested. Atmosphere of nitrogen proved to preserve S-HBsAg VLPs most efficiently, with only minor degradation at the highest temperature of 37 °C. As a result, a semi-product for the oral plant-derived vaccine against HBV with good storage capabilities was obtained.