Development and efficacy evaluation of a novel water-in-oil-in-water adjuvant for an inactivated foot-and-mouth disease vaccine

Abstract

To develop a novel water-in-oil-in-water (W/O/W) adjuvant and evaluate the effect on foot-and-mouth disease (FMD) inactivated vaccine, in this study, we prepared the novel nano-emulsion adjuvant based on QS-21 (BEA) which is composed of the mixture of mineral oil Marcol52, surfactant Tween80, oleate polyoxyethylene ether ester, polyoxyethylene palmitic acid ester and span80, cosurfactant polyethylene glycol and QS-21. The two-step emulsification method formed the W/O/W nano-emulsion with two films and three-phase structures. The effective particle diameter of the BEA was about 184 nm, and it has good thermal stability. Then, BEA was emulsified as an adjuvant to prepare for the inactivated FMDV vaccine, and BALB/c mice and pigs were immunized to evaluate its safety and immunization effect. The results showed that the inactivated BEA-FMDV vaccine significantly increased BALB/c mice and pigs’ antibodies and cytokine IFN-γ in serum. Meanwhile, the pig-neutralizing antibodies were higher than control group. Safety tests found no symptoms of FMD or significant toxic reactions. After 28 days of immunization, the protection rate can reach 93.3%. The BEA vaccine had good stability at 4 °C, no stratification after 180 days, and the content of 146S in the vaccine did not decrease. In conclusion, the BEA prepared in this study is suitable for FMDV inactivated vaccine and is an effective adjuvant.

Keywords:

• Adjuvant
• nano-emulsion
• foot-and-mouth disease virus
• immune efficacy
• thermal stability

Acknowledgments

We are grateful for the technical support from the College of Veterinary Medicine at Gansu Agricultural University and China Agricultural Vet Biological Science and Technology Co., Ltd.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Institutional review board statement

All animal experiments were approved by the Animal Ethical and Experimental Committee of Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences (approval number: LVRIAEC2022-008).

Additional information

Funding

This work was supported by the Youth Science and Technology Fund program of Gansu Provine under Grant [20JR5RA085].