Tissue-specific accumulation of latency-associated transcripts in herpes virus-infected rabbits.

PURPOSE Herpes simplex virus (HSV) DNA persists in the corneas of patients and animals with a history of herpetic keratitis. The purpose of this study was to detect viral transcripts in the corneas of latently infected rabbits with a history of herpetic keratitis to determine whether the viral DNA represents latent virus, characterized by the restricted transcription of HSV genes and accumulation of the stable latency-associated transcripts (LATs), as occurs in neurons. METHODS Rabbits were injected in the subalveolar mucosa with HSV strain RE. After 30 days, corneas were infected by intrastromal injection of HSV. Corneal disease was evaluated, and 7 to 378 days after infection, the rabbits were killed. DNA and RNA were isolated from corneas and trigeminal ganglia and amplified by PCR using gene-specific primers. RESULTS Herpetic keratitis developed in all rabbits. All corneas of these immune rabbits contained viral DNA as many as 120 days after infection and then the frequency decreased over the next 260 days. Overall, viral DNA was detected in all ganglia and in 57% of corneas. All latently infected ganglia but no corneas contained LATs. Transcripts of the early viral gene for thymidine kinase were detected in 23 of 30 ganglia and 10 of 17 corneas. Transcripts for the late viral glycoprotein C were not detected in either tissue. CONCLUSIONS These data document that after HSV keratitis, viral DNA persists in corneas in the absence of stable LATs and with restricted expression of other viral genes.