Structure-function analysis of a protein encoded by the BHV-1 latency related gene

Bovine herpes virus 1 (BHV-1) is a significant viral pathogen in cattle that induces a myriad of clinical symptoms. These symptoms include: conjunctivitis, upper respiratory tract infections, genital disorders, and abortions. BHV-1 infection can also lead to transient immune-suppression, which predisposes cattle to secondary bacterial infection leading to life-threatening pneumonia referred to as bovine respiratory disease (BRD). Following acute infection, BHV-1 establishes latency in sensory neurons within trigeminal ganglia. Reactivation of the virus can occur periodically, resulting in virus transmission. The latency-related (LR) RNA is the only abundantly expressed transcript in latently infected sensory neurons and it encodes several proteins, including ORF2, as well as two micro-RNAs. My dissertation work has focused on trying to understand how the LR gene is able to promote establishment and maintenance of latency, specifically through elucidating the mechanism of function of the LR encoded protein ORF2. ORF2 inhibits apoptosis and also interacts with Notch signaling receptors, inhibiting their ability to activate certain BHV-1 promoters and enhance productive infection. The studies presented here identified, through mutational analysis, distinct domains in ORF2 that regulate its stability, localization, and functional properties. Furthermore, ORF2 is able to affect different cellular processes and promote a mature neuronal phenotype through inhibition of the Notch pathway. Lastly, a subset of ORF2 was associated with chromatin and preferentially associated with single stranded DNA. Collectively, these studies suggest that ORF2 by interfering with apoptosis and the Notch pathway and through its ability to bind DNA plays a role in regulating certain aspects of the latency-reactivation cycle. ORF2, in general, enhances survival of infected neurons, promotes a mature neuronal phenotype and consequently increases the pool of latently infected neurons