Dual-functional emulsifier based nano-emulsion adjuvant effectively enhanced immunogenicity of recombinant respiratory syncytial virus vaccine in mice

Oil-in-water nano-emulsion adjuvant (NEA) has been utilized for many years in the development of subunit or/and recombinant vaccines. Nevertheless, worries have been expressed about the safety and potential biological activities of the emulsifier. Herein, tocopheryl polyethylene glycol 1000 succinate (TPGS), which acts not only as an emulsifier but also as an immunostimulant, was used for the preparation of NEA. Benefiting from the hydrophilic-hydrophobic nature of TPGS, NEA possess a homogeneous structure with an extremely narrow size distribution (approximately 160 nm in diameter, polydispersity index <0.15), and exhibits excellent stability over 6 months under test conditions.

When such an NEA was used with a recombinant respiratory syncytial virus (RSV) vaccine, the adjuvanted vaccine induced enhanced humoral and cellular immunity in mice compared to the non-adjuvanted vaccine. This is the initial documented finding of TPGS adjuvanticity in an intramuscularly injected vaccine. Furthermore, the TPGS-based NEA showed elevated adjuvant potency compared to the MF59-like emulsion adjuvant assessed. These results imply the potential of NEA as an alternative adjuvant for developing recombinant vaccines with enhanced immunity.

Materials

Tocopheryl Polyethylene Glycol 1000 Succinate (TPGS) was purchased from PMC Isochem. Squalene, sodium citrate, citric acid, Tween 80 and Span 85 were purchased from Hubei Renfu Pharmaceutical excipients Co., Ltd. PBS was purchased from Gibco (10010-031). The recombinant respiratory syncytial virus (RSV) pre-F protein (derived from human respiratory syncytial virus A [Strain A2]) was produced by a stable Chinese Hamster Ovary (CHO) cell line (Nanjing GenScript Biotechnology Co., Ltd).

Shuoyao Song, Man Qiao, Jing Yang, Caixia Su, Shuya Zhang, Xiayao Cao, Zhihua Liu, Xia Han, Guangjie Tong, Yelin Xiong, Zhilei Liu, Quanyi Yin, Dual-functional emulsifier based nano-emulsion adjuvant effectively enhanced immunogenicity of recombinant respiratory syncytial virus vaccine in mice, Journal of Drug Delivery Science and technology, Volume 100, 2024, 106098, ISSN 1773-2247, https://doi.org/10.1016/j.jddst.2024.106098.