Equine respiratory disease is no fun for horse or owner, and it can have a significant economic impact on the performance horse industry in both cost of treatment and in training and performance days lost.
Equine rhinitis B virus (ERBV) is a respiratory disease that affects horses worldwide, but researchers are still working to fully understand it. Current tools for detecting the virus are limited and usually concentrate only on one of the three known serotypes of the virus.
In an effort to learn more about ERBV and find a more effective and efficient diagnostic tool, researchers from the University of Melbourne, in Australia, set out to develop an enzyme-linked immunosorbent assay (ELISA) that detects antibodies to each of the three known serotypes of ERBV.
“When the (ERBV) virus infects, the immune system of the host usually responds by making antibodies to the outer surface of the virus’ protein shell,” relayed Carol Hartley, PhD, research fellow at the university's Center for Equine Infectious Disease.
Hartley explained that through previous studies, researchers have identified three different serotypes of ERBV by studying differences in each serotype’s protein shell. Because each serotype is unique, the antibodies made in response to it are unique, as well. The team used this information to help them develop the ELISA for this study.
The researchers first tested the ELISA using blood serum samples from 60 horses naturally infected with ERBV and found it to be effective in differentiating between the three serotypes. They then used it to study the prevalence of ERBV in a group of 50 weanlings from two breeding farms in New South Wales, Australia. Three samples were taken from each foal “regardless of respiratory symptoms” at 4-6 months of age, 7-9 months, and 11-13 months.
The team found that:
- Weanlings' samples contained antibodies to all three serotypes of ERBV;
- 56% of weanlings tested positive to two ERBV serotypes simultaneously;
- 12% of weanlings tested positive to all three ERBV serotypes simultaneously; and
- Some weanlings tested positive in the first and third samples, but not in the second, indicating a re-infection with the same ERBV serotype can occur, and the virus is circulating through the population.
The researchers concluded, “Given the high seroprevalence (presence of antibodies in blood serum) and evidence for circulating ERBV in these populations, it suggests that ERBV is an excellent candidate to follow to determine its importance as a respiratory pathogen. If we can understand more about the contribution of these viruses to respiratory disease … then we can begin to develop methods for their control (e.g., vaccines).”
The study, “Seroprevalence study of Equine rhinitis B virus (ERBV) in Australian weanling horses using serotype-specific ERBV enzyme-linked immunosorbent assays,” was published in Journal of Veterinary Diagnostic Investigation in September.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.