UNDERSTANDING THE ROLE OF EPSTEIN BARR VIRUS IN T CELL AND NATURAL KILLER CELL LYMPHOPROLIFERATIONS AND MALIGNANCIES

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Epstein Barr virus (EBV) is a common herpesvirus that infects the majority of the human population for the lifetime of each individual. The vast majority of individuals are unaware that they have been infected because the virus is kept under tight control by their immune system. Although EBV is most well known for causing glandular fever, it is also associated with cancers in a small number of individuals. These cancers usually occur in the cells infected as part of the natural life cycle of the virus, B lymphocytes and epithelial cells. However, on rare occasions EBV can also infect cells that are not involved in the lifecycle of the virus, T lymphocytes and Natural killer (NK) cells. Infection of these cell types always results in serious, life-threatening diseases including cancers. These diseases are extremely difficult to treat and have a very poor clinical outcome, usually measured in survival from weeks to months. There is an urgent need to better understand the pathology of these EBV-associated T/NK cell diseases in order to develop new effective, personalized therapies.Progress into understanding these diseases has been extremely slow, due to the rarity of the diseases and our inability to infect T/NK cells in the lab. However, we have addressed both these issues. We currently have a bank of blood samples from UK patients with EBV-associated T/NK cell diseases ready for analysis. Furthermore we have optimized the culture conditions and have generated matching EBV-positive T/NK cell lines from the patients' samples. Finally, and perhaps most importantly, we have managed to reproducibly infect T cells in our laboratory, which for the first time will allow us to examine how EBV triggers these T/NK cell diseases and induces their transformation into malignancy. We have four key objectives. (1) Using patient blood, we have identified white blood cells and chemical signals (cytokines) from the microenvironment which are required to help the patients' EBV-infected T/NK cells to grow in culture. We plan to replicate these conditions in the lab to help the newly-infected T/NK cells grow and determine how EBV, the surrounding cells and cytokines contribute to the growth of newly-infected T/NK cells. (2) Once the growth conditions are optimized, we will examine how specific EBV gene products able to stimulate the chronic inflammation observed in the EBV-associated T/NK cell diseases. (3) By replicating the EBV infection and chronic inflammation in our cell cultures, we will examine how EBV and chronic inflammation drive the infected cells to grow indefinitely and dysregulate the anti-EBV immunity. (4) We have established a new analysis tool, which labels the EBV-infected cells with markers for EBV and markers for the cell type. We can expand the range of markers to identify potential new drug targets on the EBV-infected cell to include therapeutic antibodies such as anti-CCR4 (mogamulizumab) currently in phase 2 clinical trial for peripheral T cell lymphoma. Furthermore, we can culture the matching ex-vivo EBV-infected T/NK cells, as above, in the presence of the drug to determine sensitivity to the drug. This is the first study of its kind to analyse the contribution of EBV to the EBV-associated T/NK cell diseases by combining ex-vivo patient samples and primary infected T/NK cells. We anticipate that by understanding how EBV causes the diseases, either directly or in combination with other cells and cytokines of the surrounding microenvironment, and by monitoring disease progression both in vitro and in vivo, we will develop a better understanding of alternative novel therapeutic options. Finally, the assays we have established to examine the potential new treatments will have wider benefit to the EBV-associated T/NK cell disease patient groups if the study were taken to trial, based on the findings of this study. The results will identify potential drugs for personalized treatment options.