Second generation inactivated eastern equine encephalitis virus vaccine candidates protect mice against a lethal aerosol challenge.
Authors: Honnold Shelley P, Bakken Russell R, Fisher Diana, Lind Cathleen M, Cohen Jeffrey W, Eccleston Lori T, Spurgers Kevin B, Maheshwari Radha K, Glass Pamela J
Journal: PloS one
Summary
Eastern equine encephalitis virus (EEEV) poses a significant biosecurity threat to equine populations and represents an occupational hazard for professionals handling infected animals, yet current vaccine options remain limited in efficacy and availability. Researchers tested three inactivated vaccine formulations derived from an attenuated EEEV strain in mice, using different inactivation methods (formalin, INA chemical treatment, and gamma irradiation) across various doses and administration schedules, then challenged vaccinated animals with lethal aerosol exposure. Formalin-inactivated and gamma-irradiated candidates provided partial to complete protection depending on vaccination protocol, whilst the INA-inactivated formulation failed to generate meaningful protection regardless of route, dose or schedule—notably, neutralising antibody titres proved the most reliable predictor of protection rather than general immunoglobulin responses. These findings suggest that inactivated EEEV vaccines using formalin or radiation-based approaches warrant progression to further development and potential clinical evaluation, which could eventually offer equine veterinarians and stud farms more robust preventative strategies against this economically damaging and potentially fatal viral disease. For practitioners, this work indicates that future EEEV vaccine development should prioritise formulations capable of generating strong neutralising antibody responses, and highlights the importance of considering inactivation methodology when evaluating novel vaccine candidates.
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Practical Takeaways
- •This research supports development of inactivated EEEV vaccines using formalin or gamma-irradiation methods as potential human therapeutics, though equine application remains unclear
- •Vaccine efficacy depends on induction of neutralizing antibodies; future vaccine development should prioritize this immune response mechanism
- •Results are preliminary (mouse model only); clinical efficacy in horses or humans would require further evaluation before practical implementation
Key Findings
- •Formalin-inactivated CVEV1219 (fCVEV1219) and gamma-irradiated CVEV1219 (gCVEV1219) provided partial to complete protection against aerosol challenge in mice
- •INA-inactivated CVEV1219 (iCVEV1219) failed to provide substantial protection by any route, dose, or schedule tested
- •Neutralizing antibody response was the best correlate of protection, rather than virus-specific IgG or IgA