Epstein-Barr Virus Driven Tonsillar Versus Peripheral B-cell One-Carbon Metabolic Network Remodeling - Abstract Epstein-Barr virus (EBV) is the etiologic agent of infectious mononucleosis, is the major trigger for multiple sclerosis and is associated with a range of lymphoproliferative disorders and carcinomas. EBV is spread between hosts through the oral cavity, where it crosses epithelial barriers to infect naïve B cells in tonsil lymphoepithelial tissue. Primary EBV infection and much of the EBV lifecycle is centered in the oropharynx, which are persistently colonized. Yet, much remains to be learned about virus/host interactions that govern the oral cavity EBV lifecycle. According to the EBV germinal center model, EBV uses latency programs to navigate the B-cell compartment, initially driving B-cell activation and growth via the pre-latency, latency IIb and latency III programs. Incompletely understood cues in tonsil and related lymphoid tissues are thought to switch the EBV program to latency IIa in germinal centers. Subsequent differentiation into memory B-cells, the reservoir for lifelong EBV infection, give rise to the latency I program, comprised of a single EBV latency gene, EBNA1. However, this has remained difficult to model and limited information is available about EBV/host interactions in the tonsil microenvironment. This lifecycle is highly associated with EBV-driven malignancies, with a heavy disease burden in craniofacial regions, including Burkitt lymphoma and nasopharyngeal carcinoma. However, much remains to be learned about how EBV rewires host cell one-carbon (1C) metabolism to support key aspects of the viral lifecycle in tonsillar versus peripheral blood B-cells. We therefore used metabolomic, proteomic and CRISPR genetic approaches to identify a central role for interconnecting methionine and folate 1C metabolism pathways in support of EBV- driven B-cell transformation and the viral lifecycle. Our central hypothesis is that EBV latency programs subvert multiple levels of interconnecting methionine and folate metabolism cycles to perform non-redundant functions critical for the viral B-cell lifecycle in tonsil versus peripheral blood compartments. Using novel primary human B-cells and tonsil tissue models, our Specific Aims are therefore to: 1) Identify key mechanisms by which EBV drives newly infected tonsil and peripheral blood B-cell methionine dependency; (2) Identify key mechanisms by which methionine metabolism drives newly infected tonsil and peripheral blood Epstein-Barr nuclear antigen expression and signaling; (3) Characterize key EBV latency gene-induced methionine and folate metabolism roles in tonsil peripheral blood B-cell redox defense. Our studies will provide novel insights into crosstalk between immunometabolism, viral latency gene programs and redox defense critical for the EBV lifecycle, with relevance to novel therapeutic approaches.
