Experimental infection with equid herpesvirus 3 in seronegative and seropositive mares.

This research conducted experiments to understand the infection mechanism of equid herpesvirus 3 (EHV-3) that leads to Equine coital exanthema (ECE), a venereal disease in horses. The focus was to compare how the disease affects seronegative and seropositive mares, and how the virus excretion and antibody response differ in both groups.

Experimental Design

• The research was designed to establish an infection model for understanding Equine coital exanthema, an economically significant venereal disease impacting horses.
• The study made use of both seronegative and seropositive mares, which were inoculated topically in the perineal region with a specifically calculated quantity of EHV-3 virus.
• A designed scoring system was implemented to evaluate clinical signs, and daily body temperatures were recorded. The study also performed virological and serological investigations to examine the virus and the body’s immune response.

Observations from the Study

• The study found that typical ECE lesions appeared in all the four seronegative mares with varying clinical scores signifying differing severity of disease manifestation.
• In contrast, the two seropositive mares only developed mild ECE lesions with significantly lower clinical scores. This observation indicates that seropositive mares demonstrate a less severe reaction to the virus.
• Interestingly, both seronegative and seropositive mares shed the virus. But the duration and intensity of this shedding were lower in the seropositive mares.
• Following EHV-3 infection and re-infection, the study detected an antibody response in both groups of mares. However, seropositive mares had a more moderate antibody response than the seronegative ones. This suggests that seropositive mares may have a degree of immunity towards repeated EHV-3 infection.

Conclusions from the Research

• Through the experimental process, it was concluded that EHV-3 infection in mares could be reproducibly achieved. This experimental model could therefore be applied in future researches to understand more about this venereal disease in horses.
• The typical ECE lesions that were observed after the EHV-3 infection in seronegative mares, coupled with virus excretion and neutralizing antibody kinetics, provides valuable insight into the disease progression and host response.