Mapping bovine herpesvirus type 1 latency-related RNA in trigeminal ganglia of latently infected rabbits

Here we have used the bovine herpesvirus type 1 (BHV-1) rabbit model together with in situ nucleic acid hybridization to identify and map viral RNA present in latently infected neurons. Radioactively labeled cloned HindIII fragments representing most of the BHV-1 genome (Cooper strain) were individually hybridized to sections of trigeminal ganglia taken from rabbits during acute and latent stages of infection. Whereas all viral genomic fragments hybridized to lytically infected tissue culture cells and to acutely infected ganglia, only HindIII fragment D (map units 0.734 to 0.842) hybridized to latently infected ganglionic neurons. Additional in situ hybridization experiments using subcloned fragments of HindIII-D further mapped the latency-related viral RNA to a 1.9-kilobase region (map units 0.734 to 0.748) of the viral genome. These results indicate that BHV-1 gene transcription is restricted during the latent phase of infection; further, they suggest that specific viral transcription may be involved in establishment or maintenance of latent BHV-1 infection.