Exercise alters the immune response to equine influenza virus and increases susceptibility to infection.

The research article discusses how strenuous exercise affects the immune response of horses to influenza virus, increasing their susceptibility to infection.

Background

• The authors point out that equine influenza virus is a significant health issue in spite of ongoing vaccination programmes.
• A crucial factor is that the immune system of a horse can be negatively affected by strenuous exercise. However, how this exercise-induced alteration in lymphocyte responses (white blood cells that help fight infections) affects a horse’s immunity to the virus was unclear.

Research Methodology

• To explore this, the researchers carried out a study where vaccinated ponies were subjected to a strenuous exercise programme for five days.
• The researchers studied the T cell-mediated immune response to the virus in these ponies, by analyzing their lymphocyte proliferation and production of gamma interferon (a substance that stimulates the immune system).

Findings

• They found that this strenuous exercise resulted in a significant suppression of the ponies’ immune response to the influenza virus.
• The ponies had decreased lymphocyte proliferation and gamma interferon production.
• Importantly, these ponies also demonstrated increased susceptibility to the influenza disease after being exposed to the virus.
• In contrast, a control group of ponies that had been resting (but had received the same vaccine and were exposed to the virus) were fully protected from the disease.

Conclusions

• The findings show that the immune response in horses to the influenza virus can be hindered by strenuous exercise.
• This weakened immune response is associated with an increased susceptibility to the disease.
• These results have important implications for managing the health and training of horses, particularly regarding the timing of vaccinations and intense exercise.