THE DETECTION OF LATENCY-ASSOCIATED TRANSCRIPTS OF EQUINE HERPESVIRUS-1 IN GANGLIONIC NEURONS

Neural tissues from specific pathogen-free ponies that had been experimentally infected with equine herpes-virus 1 (EHV-1) were analysed by in situ hybridization. Digoxigenin-labelled EHV-1 BamHI fragments spanning almost the entire EHV-1 genome were hybridized to RNA in tissue sections from latently infected trigeminal ganglia. The BamHI E fragment detected EHV-1 RNA antisense to gene 63 (HSV-1 homologue ICP0) in a small number of neurons. Sixteen other BamHI fragments gave negative results in 20 sections tested with each fragment. Latency associated transcripts (LATs) were localized to the neuronal nuclei. EHV-I nucleotide sequence data in the region reveals the presence of a putative EHV-1 LAT promoter that shares similar motifs with the HSV-1 LAT promoter, including the LAT promoter-binding factor, and may have a role in EHV-1 LAT expression.