Detection of herpes simplex virus type 1 transcripts during latent infection in mice

A latent infection can be established in the trigeminal ganglia of mice after corneal inoculation of herpes simplex virus type 1 (HSV-1). With a virion DNA probe, three transcripts (2.0, 1.5, and 1.45 kilobases [kb]) were detected by Northern blot (RNA blot) analysis of RNAs isolated from the ganglia of latently infected mice. All three transcripts hybridized to a nick-translated HSV-1 DNA probe from BamHI restriction fragment B (strain F). These RNAs were mapped with subfragments of BamHI-B and with strand-specific probes. They are at least partially colinear with each other, map to a 3.0-kb PstI-MluI subfragment of BamHI-B, and are transcribed from left to right. The latent HSV-1 RNAs partially overlap the 3' end of ICP0 mRNA but are transcribed in the opposite direction. The latent RNAs were not as extensively poly(A)+ as actin mRNA. The HSV-1 transcripts detected in latently infected trigeminal ganglia did not correspond with any that have been previously identified in permissively infected cells in tissue culture. However, the 2.0-kb HSV-1 RNA present during latency was detectable at reduced levels in the trigeminal ganglia of acutely infected mice and in infected tissue culture cells. The data indicate that the pattern of viral gene expression during HSV-1 latency in the trigeminal ganglia of mice does not represent restriction of the genes actively transcribed during the lytic replication cycle in tissue culture.