Effect of different adjuvant formulations on the antibody response of horses to porcine zona pellucida proteins.

This research sought to better understand the effectiveness of different adjuvant systems on the immune response of horses to porcine zona pellucida (PZP) proteins, exploring potential candidates for a next generation PZP-based infertility vaccine. It was found that the combination of poly(I:C) with the nanoparticle adjuvant Nano-11 significantly increased specific immune responses.

Research Context

• The study was motivated by existing use of PZP proteins for inducing infertility in wildlife. To make this method more practical for controlling horse populations, improvements were needed: induce long-term infertility, lessen reaction severity at injection sites, and make administration easier.
• The future PZP-based vaccines will likely adopt controlled-release formulations and use different adjuvants from the Freund’s adjuvants currently used.

Experiment and Findings

• The response of the horse’s peripheral blood mononuclear cells to a cationic nanoparticle adjuvant known as Nano-11 was evaluated. In the experiment, they also tested Nano-11 combined with TLR agonists poly(I:C) and CpG ODN, as part of efforts to develop a suitable adjuvant system for horse immunization.
• The researchers observed an increased secretion of IL-1β and TNF in comparison to Nano-11, especially when combined with poly(I:C); however, the CpG ODN showed little effect.
• The study then examined the effectiveness of the Nano-11/poly(I:C) adjuvant at enhancing the immune response to native PZP proteins in horses. This was achieved by immunizing horses twice; once with the licensed Zonastat-H vaccine and once with PZP with the Nano-11/poly(I:C) emulsion in silicone oil.
• Another group of horses received PZP with the saponin adjuvant QA-21 also in a silicone oil emulsion.
• In the horse sera collected one month after injection, increased anti-PZP IgG antibodies were found, with the strongest response observed from Zonastat-H. Therefore, Nano-11/poly(I:C) was identified as a potential candidate for developing a more effective PZP-based immuno-contraceptive.

Conclusion

• The study concluded that Nano-11/poly(I:C) shows the potential to be integrated into the next generation of PZP-based immunocontraceptives.
• This could potentially improve the effectiveness of such tools in controlling horse populations, offering an easier administration method and reducing the severity of injection site reactions.