The use of a systemic prime/mucosal boost strategy with an equine influenza ISCOM vaccine to induce protective immunity in horses.

This research study explores how an equine influenza vaccine improves a horse’s immune response when administered using a systemic prime/mucosal boost approach. The outcome suggests this method could significantly reduce clinical signs and virus shedding period in vaccinated horses compared to unvaccinated ones when exposed to influenza virus.

Understanding the Research

To comprehend this research entirely, let’s break down the main components:

• Background of study: In horses, a natural infection usually induces long-term protective immunity characterised by mucosal IgA and humoral IgGa and IgGb responses. Much like humans, horses have an immune response that includes the production of antibodies like IgA, IgGa and IgGb when infected with a virus. These antibodies aid in the neutralisation or eradication of the virus. In horses, a previous natural infection with influenza can stimulate these immune responses, providing them with long-lasting protective immunity.
• Objective of the study: The goal of the research was to examine the potency of administering a locally prepared equine influenza vaccine to stimulate a protective IgA response.
• The Vaccine: The study utilised an immunostimulating complex (ISCOM)-based vaccine for equine influenza (EQUIP F). This vaccine contained three different strains of the virus: A/eq/Newmarket/77 (H7N7), A/eq/Borlänge/91 (H3N8) and A/eq/Kentucky/98 (H3N8).
• Procedure: A systemic prime/mucosal boost strategy was employed wherein seven ponies received the EQUIP F vaccine intranasally six weeks after an initial intramuscular immunisation. The ponies were then exposed to an aerosol challenge with the A/eq/Newmarket/1/93 reference strain after four weeks.
• Results: The experimental set-up showed that the vaccinated animals exhibited significantly reduced clinical symptoms and virus excretion compared to unvaccinated control animals. Furthermore, the vaccinated ponies showed enhanced levels of virus-specific IgA detected in the nasal washes, suggesting that the intranasal administration of EQUIP F vaccine primes the mucosal system for an enhanced IgA response following exposure to the live influenza virus.

Significance of the Study

This study provides crucial insight into how vaccination strategies can be optimised for horses, specifically against equine influenza. The systemic prime/mucosal boost strategy could be an effective method to stimulate a strong and protective immune response. This has significant implications for horse health and the equine industry overall. The results also pave the way for additional research studies to further develop and validate this approach.