THE IDENTIFICATION OF EQUID HERPESVIRUS-1 IN PARAFFIN-EMBEDDED TISSUES FROM ABORTED FETUSES BY POLYMERASE CHAIN-REACTION AND IMMUNOHISTOCHEMISTRY

Paraffin-embedded organ samples from 28 aborted fetuses and three foal s, partly archival and partly sampled in 1991, were examined by polyme rase chain reaction (PCR) and immunohistochemistry for the presence of DNA and antigens, respectively, specific for equine herpesvirus 1 (EH V-1). Virologic examination had been performed on 23 of the aborted fe tuses. DNA fragments specific for EHV-1 were identified by PCR, and EH V-1 antigens were identified in situ by immunohistochemistry, with an agreement between the methods of 94% (kappa = 0.85). Compared with vir us isolation, PCR agreement was 87% (kappa 0.69), and IH agreement was 82% (kappa = 0.47). These results showed that there was moderate to a lmost perfect agreement among the different methods and that PCR and i mmunohistochemistry are powerful tools for the identification of EHV-1 in paraffin-embedded tissues. The techniques give more rapid results than virus isolation and also detect inactivated virus, which are not identified by standard virus isolation. These techniques also make ret rospective studies possible.