Equine herpesvirus 1 (EHV-1) nucleotide polymorphism determination using formalin fixed tissues in EHV-1 induced abortions and myelopathies with real-time PCR and pyrosequencing.

The researchers used a real-time PCR and pyrosequencing to identify strains of the equine herpesvirus-1 (EHV-1) in horses. They found significant associations between particular strains and the occurrence of the autoimmune disease equine myeloencephalopathy and other neurological conditions.

Objective and Methodology

• In this study, researchers focused on the equine herpesvirus-1 (EHV-1), which is known to cause multiple diseases in horses.
• The researchers sought to identify and differentiate between EHV-1 strains with a specific single-point mutation G2254, known to be associated with equine myeloencephalopathy, and those without this mutation, which are associated less frequently with neurological disease in horses.
• To do this, the researcher extracted and analyzed DNA from preserved, formalin-fixed paraffin-embedded tissues using real-time PCR and pyrosequencing, two advanced, highly-sensitive and accurate molecular biology methods used to amplify and sequence specific DNA targets.

Key Findings

• Using the described techniques, the researchers were able to determine the exact strains of EHV-1 infecting the horses. They detected both A2254 and G2254 strains using real-time PCR, and confirmed these findings using pyrosequencing.
• There were at least two cases in which real-time PRC results were equivocal, or uncertain, and in these cases, pyrosequencing was demonstrated to be highly useful in accurately determining the infecting EHV-1 strain.
• Through this process, the researchers found the G2254 mutation strain of EHV-1 in 9.4% of the 21 abortion cases they studied, and in a much higher proportion – 86.6% – of the 15 neurological cases.

Implications of the Study

• The findings support the association between the G2254 mutation in EHV-1 and neurological disease in horses, given its significantly higher prevalence in neurological cases compared to abortion cases.
• Moreover, the study demonstrates the utility of using real-time PCR and pyrosequencing as reliable methods to identify specific strains of EHV-1 and potentially other viruses in animals. These technologies could be invaluable in managing and controlling infectious diseases in equine populations.