The gamma-herpesvirus Epstein Barr virus (EBV) is a master regulator of B-cell biology.  EBV persistently infects >95% of adults, making it one of the most successful viruses worldwide. While EBV typically establishes a safe balance with the host, it is the cause of infectious mononucleosis, is associated with multiple sclerosis and causes ~200,000 cancers per year. Intriguingly, these include B cell, T cell, NK cell lymphomas and the epithelial cell cancers gastric and nasopharyngeal carcinoma. Studies of EBV/host interactions promise to reveal key aspects of EBV pathogenesis and of B lymphocyte biology. Indeed, EBV-infected B-cells were the first human lymphocytes that could be grown in culture and remain a key source of insights into B-cell biology, including NF-kB, MYC and Notch biology.

Establishment of latency in a long-lived cellular niche and subsequent lytic reactivation in response to environmental cues is a hallmark of herpesvirus infection, yet much remains to be learned about how EBV accomplishes these important roles. According to the “germinal center model” of EBV biology, EBV subverts normal B-cell biology pathways operative in lymphoid tissues in order to establish infection, expand the pool of latently infected B-cells, persist and spread.  Despite encoding ~80 antigenic polypeptides, EBV navigates the B-cell compartment to colonize memory B-cells, the site of long-term persistence.

To drive B-cell growth transformation while also evading robust antiviral T and NK- responses, EBV uses multiple latency programs, in which combinations of viral nuclear and membrane oncoproteins and non-coding RNAs are expressed, but highly immunogenic lytic antigens remain silenced.  Knowledge remains incomplete about how epigenetic mechanisms control EBV genome program selection. It is likely that the same mechanisms underlie the pathogenesis of multiple germinal center-derived EBV-driven B-cell malignancies, including Burkitt, Hodgkin and post-transplant lymphomas. Yet, the host/pathogen interactions that dictate key EBV B-cell latency states have remained incompletely characterized.  Likewise, large questions remain to be answered, such as why EBV drives Burkitt lymphoma in regions of holoendemic malaria in sub-Saharan Africa versus nasopharyngeal carcinoma in other regions. Since primary human B-cells can be obtained in large numbers from discarded samples, we have the unique opportunity to study host/virus interactions in newly infected primary human cells.

SARS-CoV-2 is the coronavirus responsible for the COVID-19 pandemic. We have a growing SARS-CoV-2 program that leverages our experience gained in studies of EBV/host interactions.  We are using CRISPR/Cas9 approaches to characterize host factors important for SARS-CoV-2 replication, and whole cell metabolomic approaches to identify key metabolic pathways that support viral RNA expression and viral replication. Interestingly, these identify that both EBV and SARS-CoV-2 subvert folate metabolism pathways for purine nucleotide synthesis.

Current Projects include:

• CRISPR/Cas9 analysis of the EBV host/pathogen relationship. We use human genome-wide CRISPR knockout screens to gain insights into the EBV lytic switch, into epigenetic mechanisms that control distinct viral genome programs, and dependency factors necessary for growth and survival of key EBV-infected B-cell states.
• CRISPR genetic and metabolomic studies of SARS-CoV-2 replication
• Whole cell proteomic analysis to characterize EBV remodeling of B-cells in the establishment of latency versus the lytic cycle. These studies are revealing new insights into subversion of metabolic, innate immune, and cell death pathways
• We are using metabolomic approaches to characterize how EBV uses host metabolic pathways to regulate the viral genome and alter infected B-cell biology, including for B-cell transformation into immortalized lymphoblastoid B-cells.
• We use chromosome capture techniques to study how EBV rearranges viral and host genome architecture to alter gene expression
• MYC is at the heart of key aspects of EBV-infected B-cell biology.  EBV highly induces MYC in newly infected B-cells, and MYC translocations drive Burkitt lymphoma. We are studying how EBV regulates this key proto-oncogene, and in turn how it regulates the EBV lytic switch
• We are studying how EBV subverts DNA and histone methylation pathways
• Novel models to study EBV B-cell infection states and memory B-cell infection
• CRISPR/Cas9 knockout in primary human B-cells to determine effects on EBV infection and B-cell activation.

Analysis of how EBV vs. physiological B-cell stimuli such as CD40 ligand, B-cell receptor cross-linking, the TLR9 agonist CpG or cytokines cause distinct human B-cell responses, including at the level of key transcription factors such as NF-kB, IRF4 and MYC