Characterisation of CTL and IFN-gamma synthesis in ponies following vaccination with a NYVAC-based construct coding for EHV-1 immediate early gene, followed by challenge infection.

This study investigated the response of the immune system in ponies vaccinated with a construct using Equine herpesvirus-1(EHV-1) gene and the impact on defending against the virus. The findings illustrated that the vaccine triggers the immunity but doesn’t fully protect against infection.

Understanding the Research

• The study involved an investigation into how a specific breed of horses handle the Equine herpesvirus-1 (EHV-1), a common virus frequently causing respiratory and neurological diseases amongst horses. The study primarily focused on the ponies’ Cell Mediated Immunity (CMI) following an immunization.
• The construct used for the vaccination was vP1014, which is based on a vaccinia strain (NYVAC) and encompasses the immediate early gene (gene 64) of EHV-1. This particular gene functions as a target protein for an equine variant of MHC class I allele that is expressed on the A3 haplotype.
• The researchers examined young ponies that were pre-exposed to EHV-1 and carried the specific haplotype of interest. These ponies were given the vaccination either once, three times, or four times. Alongside, there was also a control group which was not given any vaccine at all.

Key Findings

• It was observed that ponies given multiple doses of the vP1014 vaccine developed increased Cytotoxic T lymphocyte (CTL) activity and interferon-gamma (IFN-gamma) synthesis. Both of these factors are critical in the body’s protection against viruses, hence, the increase indicates an improvement in the ponies’ immune response to EHV-1.
• The phenotype of the EHV-1 specific T-cells synthesizing IFN-gamma was also altered due to the vaccination. Unvaccinated ponies primarily had CD8alpha+ type T-cells producing IFN-gamma upon EHV-1 stimulation. In contrast, ponies that received multiple doses of the vaccine demonstrated an increased proportion of CD8alpha- T-cells synthesizing IFN-gamma, thereby suggesting a modification in the immune response.

Conclusion

• The research demonstrated that the vaccination with a NYVAC construct coding for gene 64 does stimulate CMI, however, this immune response alone is not sufficient to wholly protect against the challenge of infection.
• The study provides valuable insights into how vaccinia-based vaccines can stimulate CMI in ponies and thus, potentially aid in defending against diseases caused by EHV-1.