Analysis of alpha-herpesvirus genes that encode latency associated transcripts

Members of the alpha-herpesvirinae subfamily are an important group of viruses. This group of viruses is characterized by a short reproductive cycle, rapid destruction of the host cell, and a variable host range. A key attribute of these viruses is the ability to establish lifelong latent infection in sensory neurons of the natural host. The latency associated transcript (LAT) encoded by Herpes simplex virus 1 (HSV-1) and the latency related gene (LR) of bovine herpes virus 1 (BHV-1) are abundantly expressed during latency. Both are transcribed antisense relative to a viral transactivator, ICP0 and bovine ICP0 respectively. LAT and the LR gene play an essential role in latency-reactivation cycle, in part, because they inhibit apoptosis. My dissertation focused on identifying novel transcripts and small RNAs encoded within the LAT and LR gene. I identified two novel transcripts, AL3 and L2 that are encoded within the first 1.5 kb of LAT. AL3 is anti-sense to LAT and was readily detected in productively infected cells, mouse neuroblastoma cells stably expressing LAT, and trigeminal ganglia (TG) of latently infected mice. L2 was detected in neuroblastoma cells stably expressing LAT. Both transcripts have the potential to encode a protein. In addition, I found that two small RNAs, which are encoded within the first 1.5 kb of LAT, are expressed in trigeminal ganglia of mice latently infected with an HSV-1 strain that expresses LAT. In contrast, when mice were infected with a LAT null mutant these small RNAs were not detected. I also identified two families of non-protein encoding small RNAs encoded within the BHV-1 LR gene. These small RNAs have the ability to inhibit expression of bovine ICP0. In summary, I identified several viral factors encoded within the latency related genes of alpha herpesviruses, HSV-1 and BHV-1, that are likely to support the establishment and maintain of latency.