Serum and mucosal antibody testing to detect viral exposure in contact horses during an equine herpesvirus myeloencephalopathy outbreak.

This research article discusses the application of equine herpesvirus antibody testing in both nasal swabs and serum to detect exposure to the virus in nonclinical horses during a natural outbreak. The research specifically examined five horses that were potentially exposed to the virus, four of which were previously vaccinated. The results suggest that nasal mucosal antibodies provide useful information regarding viral exposure and enhance management during outbreaks.

Study Context and Aim

• This research was conducted in the context of an outbreak of equine herpesvirus type 1 (EHV-1), a highly contagious disease that affects horses.
• The study aimed to investigate the effectiveness of EHV-1 antibody testing in confirming viral exposure in non-clinical horses during an outbreak. Previously, studies had shown that horses which maintain robust serum anti-EHV-1 antibody levels along with rapidly increasing nasal mucosal antibodies seem to prevent EHV-1 infection.

Research Design

• Two horses exhibiting neurological signs of EHV-1 from one farm were admitted to an equine hospital, confirming EHV-1 presence via PCR.
• Another five horses, possibly exposed to the virus (four of which had been vaccinated against EHV-1 within the past seven months), were studied.
• These horses had their temperatures measured, and nasal swab samples and serum were collected for EHV-1 PCR and antibody quantification at various points from 1 to 29 days after possible EHV-1 exposure.

Findings and Interpretation

• None of the potentially exposed horses developed a fever or showed clinical signs of EHV-1. Tests on nasal swabs and blood were negative for EHV-1.
• Significant increase of mucosal antibodies were observed in four horses. This indicates that they were exposed to EHV-1 but neither became infected (hence termed “protected”) nor became infectious.
• The fifth horse that did not show increasing mucosal antibodies was determined to not have been exposed.
• The researchers concluded that monitoring mucosal antibodies can provide useful information about EHV-1 exposure. Combined with clinical monitoring and PCR testing, it could significantly improve the management of EHV-1 outbreaks.

Implications and Conclusions

• Regularly measuring serum and mucosal antibodies in potentially exposed horses during an EHV-1 outbreak, right from the emergence of the index case, can help to identify nonimmune horses and those that are protected.
• This could result in more informed treatment decisions for nonimmune horses and reduce the quarantine period for protected animals.