Use of an immunoperoxidase technique to detect equine herpesvirus-1 antigen in formalin-fixed paraffin-embedded equine fetal tissues.

The researchers have developed a method using an immunoperoxidase procedure to detect a virus known as equine herpesvirus-1 (EHV-1) in the tissues of horse fetuses that had been preserved in formalin and embedded in paraffin. This work suggests that this method might be useful in diagnosing virus-related miscarriages in horses.

Development and Application of the Immunoperoxidase Technique

• The researchers developed an immunoperoxidase (IP) procedure to detect EHV-1 antigens. This procedure uses the mechanism of the avidin-biotin-peroxidase complex detection technique.
• Formalin-fixed paraffin-embedded tissues from aborted equine fetuses were used as test samples.
• The procedure was most specifically applied to the liver, lung, and other tissues from 20 horse fetuses that were suspected or confirmed to have aborted due to EHV-1.

Results of the Study

• Specific staining was observed in the tissue sections from fetuses infected with EHV-1, indicating the presence of EHV-1 antigens.
• Positive IP staining was present in tissues from 7 cases that were also diagnosed as EHV-1 positive by fluorescent antibody (FA) testing and virus isolation (VI), and with visible lesions typically caused by the virus.
• There were cases that showed no IP staining; these did not display histologic lesions and tested negative for EHV-1 in FA and VI tests. This suggests a good level of specificity in the developed IP test, where negative results correspond to the absence of the virus and its effects.
• For some cases, only one of the tests (IP, VI, or FA) showed positive results, though they exhibited typical histologic lesions of EHV-1. This highlights the variability in testing and the advantage of having multiple means of disease detection.
• In one instance, IP testing was the only reliable method due to the tissues being too degraded (autolytic) for other tests like FA and VI, underscoring the utility of the developed IP method in such situations.

Implications of the Findings

• The study signifies the potential of the IP testing procedure in diagnosing EHV-1 in aborted horse fetuses.
• It could be a novel, reliable testing method beside FA and VI, especially when tissues are too autolytic for these other tests to be effective.
• Further research would be beneficial to optimize the testing process and to comprehensively evaluate the nimbleness of the IP procedure in the detection of EHV-1 and possibly other equine viruses.