RESUMO
Equine influenza A (H3N8) virus infection is a leading cause of respiratory disease in horses, resulting in widespread morbidity and economic losses. As with influenza in other species, equine influenza strains continuously mutate, often requiring the development of new vaccines. Current inactivated (killed) vaccines, while efficacious, only offer limited protection against diverse subtypes and require frequent boosts. Research into new vaccine technologies, including gene-based vaccines, aims to increase the neutralization potency, breadth, and duration of protective immunity. Here, we demonstrate that a DNA vaccine expressing the hemagglutinin protein of equine H3N8 influenza virus generates homologous and heterologous immune responses, and protects against clinical disease and viral replication by homologous H3N8 virus in horses. Furthermore, we demonstrate that needle-free delivery is as efficient and effective as conventional parenteral injection using a needle and syringe. These findings suggest that DNA vaccines offer a safe, effective, and promising alternative approach for veterinary vaccines against equine influenza.
Assuntos
Doenças dos Cavalos/prevenção & controle , Vírus da Influenza A Subtipo H3N8/imunologia , Vacinas contra Influenza/isolamento & purificação , Infecções por Orthomyxoviridae/veterinária , Vacinação/métodos , Vacinas de DNA/imunologia , Animais , Anticorpos Antivirais/sangue , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Cavalos , Vírus da Influenza A Subtipo H3N8/genética , Vacinas contra Influenza/administração & dosagem , Vacinas contra Influenza/efeitos adversos , Camundongos , Infecções por Orthomyxoviridae/prevenção & controle , Vacinação/efeitos adversos , Vacinas de DNA/administração & dosagem , Vacinas de DNA/efeitos adversosRESUMO
BACKGROUND: Serological evidence for influenza A, subtype H1 and H3 virus infections of bovines, associated with respiratory disease and decreased milk production, has been reported. Equine H3N8 influenza virus circulates widely and was responsible for the introduction of H3N8 influenza into canines. OBJECTIVE: To explore the possibility that equine H3N8 influenza might also infect bovines. METHODS: To assess the incidence of seroconversion in the field, a retrospective survey of bovine serum samples was carried out. Also, primary cultures of bovine nasal turbinate cells, and live beef calves, were studied for their permissiveness to infection. RESULTS AND CONCLUSIONS: We found serological evidence of exposure of bovines in Kentucky to H3 influenza. We demonstrate that cultured bovine respiratory epithelium is permissive for the growth of equine H3N8 influenza virus in vitro, but this virus does not replicate extensively or produce disease in experimentally inoculated cattle.