Development and Testing of Mucosal Vaccines Targeting Chronic Wasting Disease in Cervids and Rodent Models

Introduction

Chronic Wasting Disease (CWD) is spreading uncontrollably in wild cervid populations in many Canadian provinces, US states, and Scandinavia. It also poses a significant animal health and economic challenge to cervid farmers in those countries.

We developed structure-based CWD vaccines that can induce PrP^Sc-specific immune responses in immunized cervids and rodent models. However, the initial vaccine constructs were designed as injectable vaccines, which may provide little protection against CWD infections that occur via mucosal routes.

Objectives

To develop mucosal vaccine variants that can elicit protective IgA immune responses and protect wild and captive cervids from CWD infection.

Methods

We coupled our current structure-based CWD vaccines with an amphiphile, which has been demonstrated to facilitate active mucosal uptake of amphiphile-coupled vaccines. Mucosal vaccine uptake favors a strong IgA-based immune response.

Results / Discussion

The covalent coupling of the amphiphile to the structure-based vaccines was successfully completed and did not interfere with the folding of the recombinant vaccines. The efficacy of the vaccines to induce PrP^Sc-specific IgA immune responses is currently being tested in Syrian hamsters and Rocky Mountain elk. Additional experiments are underway to determine the prophylactic efficacy of the mucosal vaccine variants against oral prion infections in both Syrian hamsters and Rocky Mountain elk.

Conclusion

The vaccine efficacy trials have just been started and early-stage results on the strengths of the IgA-based immune responses are expected by the time of the Prion 2025 conference.