Emerging and Re-emerging Viral Diseases of Large Animals

A single-nucleotide polymorphism (A(2254) or G(2254)) in the DNA polymerase gene of equine herpesvirus 1 (EHV-1) has been linked to the neuropathogenic phenotype which induces equine herpes myeloencephalitis (EHM). Based upon this, a real-time PCR assay to distinguish potentially neuropathogenic from non-neuropathogenic EHV-1 strains was described in 2007. With some limitations, this assay was useful for typing purposes, but lacked the sensitivity to be used for combined detection and typing purposes. Recently, a second generation assay was described to accomplish this (1). Both the original and the new assay were then compared in terms of performance on a combination of archived isolates and clinical specimens. The results showed that the new assay had greater sensitivity and typing accuracy than the previous one and, as such, will be a valuable tool for the differentiation between neuropathogenic and nonneuropathogenic strains of EHV-1.