In-situ hybridization for demonstration of equine herpesvirus type 1 DNA in paraffin wax-embedded tissues and its use in horses with disseminated necrotizing myeloencephalitis.

This research explores the use of the in-situ hybridization technique for the detection of equine herpesvirus type 1 (EHV-1) in infected horse tissues. However, the technique did not detect the virus in spinal cord tissues of horses suffering from disseminated necrotizing myeloencephalitis (DNM), suggesting that this disorder might not be triggered by a direct viral infection.

Objective of the research

• The research aimed to describe the in-situ hybridization technique for detecting equine herpesvirus type 1 (EHV-1) in infected cell cultures and necropsy tissues. This technique involves using a particular probe to identify EHV-1 DNA.

Methodology

• The scientists used a 4.9 kb Bam HI fragment of the EHV-1 vaccine strain RacH as a probe after marking it with radioactive or non-radioactive labels.
• The probes were used to detect EHV-1 DNA in cytospin or paraffin wax-embedded preparations of infected cells.
• The non-radioactive probe was used to examine tissue sections from horse fetuses that had been aborted due to EHV-1 infection.
• For verification, EHV-1 antigen was immunostained in adjacent sections.

Results and Conclusion

• The probes successfully detected EHV-1 DNA in the infected cells, and in most cases, the positive signals were associated with nuclei.
• However, both probes and the immunostaining method failed to detect EHV-1 in the spinal cord sections of horses suffering from DNM.
• The absence of EHV-1 in the spinal cord sections supports the hypothesis that DNM may not be caused by a direct viral infection of the nervous system’s core tissues, but by an immune response.