Development of a Stable Respiratory Syncytial Virus Pre-Fusion Protein Powder Suitable for a Core-Shell Implant with a Delayed Release in Mice: A Proof of Concept Study

• Published in: Pharmaceutics Vol. 11; no. 10; p. 510
• Main Authors: Beugeling, Max, Amssoms, Katie, Cox, Freek, De Clerck, Ben, Van Gulck, Ellen, Verwoerd, Jeroen A., Kraus, Guenter, Roymans, Dirk, Baert, Lieven, Frijlink, Henderik W., Hinrichs, Wouter L. J.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 03.10.2019; MDPI
• Subjects: Antibodies; Antigens; biphasic pulsatile release; Body temperature; Chromatography; controlled release; Enzymes; freeze-dried powder; fusion protein; poly( dl -lactic-co-glycolic acid); pre-fusion; Proteins; Respiratory syncytial virus; single-injection vaccine; Sodium; Transplants & implants; Vaccines; United States > US; Netherlands; Germany
• ISSN: 1999-4923; 1999-4923
• DOI: 10.3390/pharmaceutics11100510

Currently, there is an increasing interest to apply pre-fusion (pre-F) protein of respiratory syncytial virus (RSV) as antigen for the development of a subunit vaccine. A pre-F-containing powder would increase the flexibility regarding the route of administration. For instance, a pre-F-containing powder could be incorporated into a single-injection system releasing a primer, and after a lag time, a booster. The most challenging aspect, obtaining the booster after a lag time, may be achieved by incorporating the powder into a core encapsulated by a nonporous poly(dl-lactic-co-glycolic acid) (PLGA) shell. We intended to develop a stable freeze-dried pre-F-containing powder. Furthermore, we investigated whether incorporation of this powder into the core-shell implant was feasible and whether this system would induce a delayed RSV virus-neutralizing antibody (VNA) response in mice. The developed pre-F-containing powder, consisting of pre-F in a matrix of inulin, HEPES, sodium chloride, and Tween 80, was stable during freeze-drying and storage for at least 28 days at 60 °C. Incorporation of this powder into the core-shell implant was feasible and the core-shell production process did not affect the stability of pre-F. An in vitro release study showed that pre-F was incompletely released from the core-shell implant after a lag time of 4 weeks. The incomplete release may be the result of pre-F instability within the core-shell implant during the lag time and requires further research. Mice subcutaneously immunized with a pre-F-containing core-shell implant showed a delayed RSV VNA response that corresponded with pre-F release from the core-shell implant after a lag time of approximately 4 weeks. Moreover, pre-F-containing core-shell implants were able to boost RSV VNA titers of primed mice after a lag time of 4 weeks. These findings could contribute to the development of a single-injection pre-F-based vaccine containing a primer and a booster.