Hormonal Regulation of HSV-1 Replication in Neurons

University Of Maryland Eastern Shore, Princess Anne MD

Investigators

Abstract

PROJECT SUMMARY/ABSTRACT HSV–1 infection in neurons remains a mystery. Acute infection in non-neurons is straightforward: the virus completes its entire life cycle in less than 20 hours with approximately 90 genes encoded. In neurons, the virus may establish a dormant state of infection, where the robust viral gene expression turns off with only a few exceptions. Clinically, the HSV–1 reactivation is associated with a variety of neuropathic complications, causing considerable economic/health burdens. Our studies suggested that thyroid hormone (TH or T3) played a role in the regulation of HSV–1 replication in neurons. This hypothesis was supported by our epidemiology data, which shows that patients taking levothyroxine demonstrated a lower chance of herpes zoster. We presented convincing data indicating that the TH exerted its effect by binding to its nuclear receptor TR, and the liganded TR occupied the critical HSV–1 regulatory sequences to suppress the viral gene expression and replication. In addition, our publications reveal for the first time that the latent DRG neurons exhibited much higher sodium channel activity, and that these neurons with extremely higher excitability are suppressive to viral replication. These observations lead to the hypothesis that “TH regulates HSV–1 neuronal replication by dual mechanisms: direct binding to the HSV–1 key regulatory sequences via its nuclear receptor and modulations of neuronal excitability.” In this proposal, we will first characterize the thyroid hormone-mediated regulation of HSV–1 replication in neurons during latency and reactivation using computer-guided mutagenesis to generate chimeric virus by a synthetic genome method. We hypothesize that a critical single nucleotide change within the thyroid hormone receptor element (TRE) of an important HSV-1 regulatory sequence will disrupt the TH-mediated epigenetic regulation and control the viral latency and reactivation. Next, we will determine the impact of thyroid hormone on the functional expression and activity of voltage-gated sodium channels (VGSC) during HSV–1 latency and reactivation. We will first verify whether TH increases Na+ channel function through upregulation of growth factors via MAPK/ERK signaling. We will next use TH or antagonists to monitor the degrees of latency and reactivation. We hypothesize that TH antagonists will increase HSV–1 reactivation from latently infected mice. To test the hypothesis, we will determine the effects of TH on the cytokine production in regulating the VGSC activity via modulating signaling pathways or intracellular trafficking. Finally, we will respond to the RFA and design a novel enrichment academy to promote DEIA at UMES for URM students focusing on AAV gene delivery into neurons to investigate HSV–1 latency and other diseases. UMES has been emphasizing DEIA since its beginning 137 years ago, and we are proud to be recognized with an NIH R25 Science Education Partnership Award (SEPA) and a five-year HHMI Driving Change (DC) Award to promote STEM research/education for underrepresented college students. We will build a coherent program focusing on virology and AAV gene delivery. We will first strengthen our SEPA virology workshop for high-school students. We will next develop a curriculum for students to manufacture gene delivery vectors based on adeno-associated virus (AAVs) in collaboration with the University of Pittsburgh via the NIH BRAIN initiative. We will finally apply the knowledge we learn to design AAV overexpressing dominant negative TR for our HSV–1 studies. We anticipate the SEPA and HHMI DC will become feeder/pipeline programs so that well-prepared students will receive graduate education and conduct research. In summary, we seek to characterize the mechanism of HSV–1 latency/reactivation regulated by thyroid hormone. The results will generate invaluable information pertaining to how viruses and the host neurons accomplish an armistice to establish latency. We will also design an innovative program developing URM students to make them knowledgeable and competitive in sciences, particularly in virology.