Safety and immunogenicity of a novel cold-adapted modified-live equine influenza virus vaccine.

The research focuses on the development and assessment of a new live vaccine to prevent equine influenza virus (EIV) in horses. The vaccine, which is derived from a new cold-adapted strain, was found to be safe and capable of inducing an immune response without causing any notable side effects.

Study Methodology

• This study involved the creation of a modified-live vaccine for the prevention of EIV based on a newly-identified cold-adapted strain. This virus strain was made to include surface proteins (HA, NA) from a wild-type strain and internal proteins from an already-attenuated cold-adapted donor strain.
• The vaccine was administered to horses via a nasal spray at a certain dosage. Their health conditions were monitored throughout the experiment, and samples were taken for virus titration.
• For further exploration of the vaccine’s safety and impact, a couple of horses in each group were euthanized for histological examination and viral titre measurements in their organs.
• The serum samples and nasal secretions were gathered from the horses to assess their serological response to the vaccine. Cell-mediated immunity was evaluated via lymphocyte proliferation after restimulation in vitro.
• The vaccinated horses were exposed to the wild-type virus after 28 days to assess the vaccine’s protective capabilities. Any variations in their clinical conditions and serological responses were observed, along with the viral load in their nasal swabs.

Results and Conclusion

• The results revealed that the vaccine, when delivered in a single intranasal dose, had no adverse consequences. The vaccinated horses and pregnant mares did not produce detectable antibody levels by notable post-vaccination days, as per the HI reaction and ELISA.
• Secretory antibodies were found on day 7 and reached their highest levels on day 14.
• The vaccinated horses also showed a cell-mediated immune response by day 14, as seen in vitro.
• Post-exposure to the wild-type virus, the yearlings were seen to be protected, suggesting that the vaccine was effective.
• The researchers concluded that the single intranasal administration of this vaccine is safe and effectively stimulates an immune response in yearlings and pregnant mares, besides offering protection against EIV.