PROJECT 2 – PROJECT SUMMARY/ABSTRACT Project 2. Uncovering Mechanisms of the Lymphoid Oncogenesis of Epstein-Barr Virus and Kaposi’s Sarcoma Herpesvirus Bill Sugden, Project Leader; Paul Lambert and Eric Johannsen, Co-Leaders EBV causes several lymphoid cancers; EBV and KSHV together cause Primary Effusion Lymphomas (PELs). We have uncovered previously unrecognized cellular drivers of Burkitt Lymphomas (BL) caused by EBV with screens using CRISPR/Cas9 and sgRNAs to all human genes in early passage BL cells. PEL and BL are AIDS- defining malignancies. We have developed a new approach to inhibit EBV in these early passage BL cells after the comprehensive CRISPR screen and identified cellular genes which EBV must regulate for the lymphomas to be maintained. These approaches have worked and ensure that our collaboration with Dr. Johannsen to screen EBV+ DLBCLs in Project 4 will be informative. We are examining our newly developed co-transformation of peripheral and tonsillar B-cells with EBV and KSHV to elucidate it mechanistically. We focus on EBV because its causal role in PEL was formerly unappreciated. We are collaborating with Dr. Paul F. Lambert (Project 1), to define EBV’s and KSHV's roles in PEL tumorigenesis studying co-transformed cells as xenografts in NSG mice. These cells grow better in the peritoneal cavities of NSG mice than do cells infected only with EBV and express genes characteristic of bona fide PELs. We are testing contributions of the peritoneal cavity to the tumor-growth of co-transformed cells and PEL cell lines.