Rapid, single-step differentiation of equid herpesviruses 1 and 4 from clinical material using the polymerase chain reaction and virus-specific primers.

Sets of primers were designed which enabled specific amplification of homologous regions of the glycoprotein C and gene 76 genetic loci of equine herpesviruses 1 and 4 (EHV-1 and EHV-4). The resultant virus-specific polymerase chain reaction (PCR) products arising from each loci could be discriminated easily on the basis of size on an agarose gel, allowing rapid differentiation of the two equine herpesviruses. Specificity of the amplifications were confirmed by Southern hybridization and restriction endonuclease digestion. The PCR test was applied to nasal swab samples from weanling foals and to archival aborted fetal tissue samples and the results compared to those obtained by virus isolation. A strong correlation was found between this PCR assay and virus isolation methods of EHV-1 and EHV-4 detection and discrimination.