Protective efficacy of a bivalent equine influenza H3N8 virus-like particle vaccine in horses.
Abstract: Equine influenza (EI) is a highly contagious acute respiratory disease of wild and domesticated horses, donkeys, mules, and other Equidae. EI is caused by the Equine Influenza virus (EIV), is endemic in many countries and outbreaks still have a severe impact on the equine industry globally. Conventional EI vaccines are widely used, but a need exists for a platform that facilitates prompt manufacturing of a highly immunogenic, antigenically matched, updated vaccine product. Here we developed a plant-produced bivalent EI virus-like particle (VLP) vaccine candidate which lacks the viral genome and are therefore non-infectious. We conducted a pilot safety/dose response study of a plant produced bivalent VLP vaccine expressing the HA proteins of Florida clade (FC) 1 and FC2 EIV in 1:1 ratio. Groups of three EIV seronegative horses were vaccinated using four antigen levels (0 sham control, 250, 500, 1000 HAU/dose component). Two doses of vaccines were administered one month apart, and horses were observed for adverse reactions, which were minimal. Sera were collected for hemagglutination inhibition (HI) testing using FC1 and FC2 viruses. One month after the second dose, all horses were challenged with the aerosolized FC1 virus. Horses were observed daily for clinical signs, and nasopharyngeal swabs were collected to quantify viral RNA using qPCR and infectious virus by titration in embryonated hens' eggs. Results showed that all vaccinated groups seroconverted prior to challenge. Post-challenge, both clinical scores and virus shedding were much reduced in all vaccinates compared to the sham-vaccinated controls. We conclude that the VLP vaccines were safe and effective in this natural host challenge model. A safe, efficacious, new-generation bivalent EI VLP vaccine produced in plants, which can promptly and regularly be antigenically matched to ensure optimal protection, will pave the way to highly competitive commercially viable vaccine products for all economic environments globally.
Copyright © 2025 The Authors. Published by Elsevier Ltd.. All rights reserved.
Publication Date: 2025-02-11 PubMed ID: 39938315DOI: 10.1016/j.vaccine.2025.126861Google Scholar: Lookup
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- Journal Article
Summary
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The research article presents a study on the development and testing of a new plant-based vaccine for equine influenza, a highly contagious respiratory disease in horses and related species. The new vaccine candidate uses virus-like particles to stimulate an immune response without causing disease, and the researchers found that it was safe and effective in a pilot study.
Background
- Equine influenza (EI) is a highly contagious respiratory disease affecting horses and related species such as donkeys and mules.
- The disease is caused by the Equine Influenza virus (EIV) and is prevalent in many countries, causing significant economic impact on the equine industry.
- Existing vaccines for EI are widely used but there is a need for a platform for quick production of antigenically matched, updated vaccines with a high immune response.
Development of the Vaccine Candidate
- The researchers developed a bivalent EI vaccine candidate using virus-like particles (VLPs) expressed in plants.
- VLPs mimic the structure of the virus but do not contain viral genetic material, making them non-infectious.
- This vaccine candidate expressed the hemagglutinin (HA) proteins of the Florida clade (FC) 1 and FC2 EIV, two strains of the virus.
Pilot Safety/Dose Response Study
- A pilot study was conducted on groups of three EIV seronegative horses, using four antigen levels (0 sham control, 250, 500, 1000 HAU/dose component).
- Two doses of vaccines were given one month apart. The horses were observed for adverse reactions, which were minimal.
- Blood samples were collected for hemagglutination inhibition (HI) testing using FC1 and FC2 viruses.
Challenge with the Aerosolized Virus
- One month after the second dose, all horses were exposed to aerosolized FC1 virus.
- Clinical signs were observed daily, and nasopharyngeal swabs were collected to quantify viral RNA and infectious virus.
- Results showed that all vaccinated horses developed an immune response to the vaccine (seroconversion) before the viral challenge.
- Additionally, both the severity of disease symptoms and the amount of virus shedding were significantly reduced in vaccinated horses compared to the control group.
Conclusions and Implications
- The researchers concluded that the VLP vaccine was both safe and effective in the natural host challenge model.
- The study paves the way for a new generation of EI vaccines that can be quickly produced in plants and regularly updated for optimal protection, potentially offering a highly competitive, commercially viable vaccine product for different economic environments around the world.
Cite This Article
APA
O'Kennedy MM, Reedy SE, Abolnik C, Khan A, Smith T, du Preez I, Olajide E, Daly J, Cullinane A, Chambers TM.
(2025).
Protective efficacy of a bivalent equine influenza H3N8 virus-like particle vaccine in horses.
Vaccine, 50, 126861.
https://doi.org/10.1016/j.vaccine.2025.126861 Publication
Researcher Affiliations
- Council for Scientific and Industrial Research (CSIR), Biomanufacturing Technologies, Future Production: Chemical Cluster, South Africa; Department of Production Animal Studies, University of Pretoria, South Africa. Electronic address: mokennedy@csir.co.za.
- University of Kentucky, Department of Veterinary Science, USA.
- Department of Production Animal Studies, University of Pretoria, South Africa.
- University of Kentucky, Department of Veterinary Science, USA; University of Haripur, Department of Public Health, Pakistan.
- Council for Scientific and Industrial Research (CSIR), Biomanufacturing Technologies, Future Production: Chemical Cluster, South Africa.
- Council for Scientific and Industrial Research (CSIR), Biomanufacturing Technologies, Future Production: Chemical Cluster, South Africa.
- University of Kentucky, Department of Veterinary Science, USA.
- School of Veterinary Medicine & Science, University of Nottingham, United Kingdom.
- Irish Equine Centre, Kildare, Ireland.
- University of Kentucky, Department of Veterinary Science, USA.
MeSH Terms
- Animals
- Horses
- Influenza Vaccines / immunology
- Influenza Vaccines / administration & dosage
- Influenza Vaccines / adverse effects
- Influenza A Virus, H3N8 Subtype / immunology
- Orthomyxoviridae Infections / prevention & control
- Orthomyxoviridae Infections / veterinary
- Orthomyxoviridae Infections / immunology
- Vaccines, Virus-Like Particle / immunology
- Vaccines, Virus-Like Particle / administration & dosage
- Horse Diseases / prevention & control
- Horse Diseases / immunology
- Antibodies, Viral / blood
- Female
- Vaccination / veterinary
- Vaccine Efficacy
- Virus Shedding
- Pilot Projects
Conflict of Interest Statement
Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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