Regulatory Crosstalk Between Human Endogenous Retroviruses, HIV, and EBV, in Lymphoma

PROJECT SUMMARY/ABSTRACT Approximately 8% of the human genome is composed of sequences directly derived from germline infections of diverse retroviruses, which have accumulated over the past ~100 million years of mammalian evolution. None of these human endogenous retroviruses (HERVs) are known to represent fully functional retroviruses, but most

have retained noncoding regulatory sequences that can control expression of cellular genes acting as promoters or enhancers, and some still encode proteins with various functional activities. While HERV sequences are often ignored as merely inconsequential ‘junk’ DNA, there is evidence that a subset of these elements play crucial

roles in human physiology and disease, including cancer. Our previous work, as well as that of others, have shown that both HIV and EBV infections activate certain HERV families that have oncogenic activities, and our preliminary data reveal an overlap between these elements. Given that diffuse large B cell lymphomas (DBCL)

are frequently associated with EBV infection in people living with HIV, we hypothesize that there is a complex intercellular regulatory crosstalk between AIDS related (AR)-DLBCL, HIV-infected T cells and the tissue microenvironment, that is in part mediated by a specific subset of HERVs and their derived products that are

synergistically activated and promote oncogenesis. We will study DLBCL obtained from patients with or without EBV (and with or without HIV) from the USA and Brazil, which will be comprehensively characterized pathologically and molecularly using single-cell genomics and spatial transcriptomics. We will analyze these data

using computational tools we have tailored to profile and link HERV and gene expression. Furthermore, we will establish in vitro models to dissect with precision the functional impact of HERV on the crosstalk between T cells infected by HIV and B cells with or without EBV. We will also determine if differential HERV expression creates

neoantigenic epitopes, a feature that can be exploited for immunotherapy. This will be accomplished through three specific aims: 1) Characterize and profile HERV regulation and expression within single cells in DLBCL and AR-DLBCL; 2) Establish in vitro models to dissect the interaction between cellular and endogenous and

exogenous viruses in AR-DLBCL; 3) Identification of neo-antigenic HERV epitopes in DLBCL and ascertain if cloned HERV specific CTL can lyse lymphoma cells in vitro. Our team consists of specialists in lymphoma biology and medicine, transposable elements and HERVs, HIV and EBV viral immunology. Together, we will generate

understandings of how HERVs contribute to the pathogenesis of AR-DLCBL, and identify new antigenic targets for novel therapies.