Prevalence of serum neutralising antibody to equine rhinitis A virus (ERAV), equine rhinitis B virus 1 (ERBV1) and ERBV2.

This research studied the incidence of specific neutralizing antibodies (to equine rhinitis A virus, and B viruses 1 and 2) within a horse population ranging from newborn to 22 years of age. It highlights significant presence of these antibodies in most of the horses, with maternal antibodies being passed down to foals. The study also demonstrates the fluctuating presence and titres of these antibodies over time.

Objective and Methodology

• This research aimed to investigate the prevalence of specific serum neutralising antibodies — to the equine rhinitis A virus (ERAV), and the equine rhinitis B viruses 1 and 2 (ERBV1 and ERBV2) — within a horse population.
• The study used serum samples collected from 291 horses, corresponding to a total of 381 samples. The age of horses studied ranged from newborn to 22 years old.
• In the case of certain horses, pairs of serum samples were collected, the first one when they were new to a training centre, and a second sample about seven months later.

Key Findings

• The analysis of 381 serum samples found that the presence of ERAV, ERBV1, and ERBV2 specific antibodies was at 37%, 83%, and 66%, respectively.
• There was evidence of maternal antibody transfer, as foals were found with the antibodies 12 hours after suckling. But by the time the foals reached 10-12 months old, ERAV antibodies were not detected in them, while ERBV antibodies remained common.
• When a group of 44 Thoroughbred horses was assessed after their introduction into a training centre, 18% were found with ERAV antibodies. However, when retested seven months later, this rose to 61%. This indicates seroconversion (production of specific antibodies due to infection) to ERAV in 43% of those horses during their first seven months at the training stable.
• Interestingly, while ERAV antibody titre was relatively high, ERBV1 and ERBV2 antibody titres were comparatively low and often dropped below detectable levels over time, a trend seen in line with new seroconversions.

Conclusion

• This study provides valuable insights into the prevalence and dynamics of ERAV, ERBV1, and ERBV2 neutralising antibodies in a horse population over time.
• The research could be important to better understand horse immunity and disease transmission dynamics. It also underlines the potential influence of environmental factors (like new training conditions) on horse health and immunity.