Immune responses to commercial equine vaccines against equine herpesvirus-1, equine influenza virus, eastern equine encephalomyelitis, and tetanus.

This research article investigates how effectively different commercially available vaccines for horses trigger immune responses against four specific diseases: equine herpesvirus-1 (EHV-1), equine influenza virus (EIV), eastern equine encephalomyelitis (EEE), and tetanus. The study reveals that the effectiveness of the vaccines varies widely, and this can be attributed to differences in the composition and formulation of each vaccine.

Research Approach

• The researchers conducted two trials to analyze the antigenicity (i.e., the ability to trigger an immune response) of various commercially available horse vaccines that are approved for use in the United States.
• In Trial I, they compared the serological (blood serum) responses to vaccines produced by three different manufacturers against EIV, EHV-1, EEE, and tetanus. These vaccines were given either as multivalent preparations (containing several antigens) or as separate vaccine courses.
• Trial II examined vaccines from two manufacturers that were designed to protect against EHV-1 related abortions in horses. In addition to measuring serological responses, this trial also measured the production of EHV-1-specific interferon-gamma (IFN-gamma) mRNA – a key component of the immune response.

Key Findings

• In Trial I, the researchers found significant differences in how well different vaccines stimulated immune responses, indicating that the choice of product is an important consideration. However, it was challenging to find vaccines that provoked strong immune responses against respiratory viruses.
• The most striking variation in vaccine performance was observed with the tetanus antigen, suggesting that some vaccines may be more effective than others at targeting this particular disease.
• In Trial II, both tested vaccines resulted in significant antibody responses and showed evidence of EHV-1-specific IFN-gamma mRNA production, implying they could effectively stimulate the immune system.
• Overall, the study found substantial variations in the effectiveness of different vaccines. Importantly, the vaccines that triggered the best immune response were not necessarily produced by the same manufacturer.

Conclusion

• The varying effectiveness of these vaccines could be attributed to differences in their antigen load (the quantity of substances that provoke an immune response) and adjuvant formulation (components that enhance the body’s immune response to an antigen).