THE PREVALENCE OF LATENT EQUID HERPESVIRUSES IN THE TISSUES OF 40 ABATTOIR HORSES

Equid herpesviruses 1 or 4 (EHV-1 or -4) were isolated by cocultivatio n from 60% of 40 horses examined at slaughter. The lymph nodes drainin g the respiratory tract were the most common source of virus. EHV-1 or EHV-4 was never isolated from the trigeminal ganglia (SLG). The polym erase chain reaction (PCR) detected virus in 87.5% of bronchial lymph nodes and a similar level in the trigeminal ganglia that were examined . By both assays approximately one third of the positive animals harbo ured both viruses. Equid herpesvirus 2 (EHV-2) was isolated from all b ut one of the horses and from >75% of the lymph nodes draining the res piratory tract; alpha viruses were isolated only in the presence of EH V-2. The results indicate that latent EHV-1 and EHV-4 are widespread i n the equine population and that the primary site of latency is the ly mph nodes of the respiratory tract.