Identification of Igh Gene Rearrangement and Immunophenotype in an Animal Model of Epstein-Barr Virus-Associated Lymphomas

Epstein–Barr virus (EBV) is a human oncogenic herpesvirus associated with lymphoma and nasopharyngeal carcinoma. Because the susceptible hosts of EB virus are limited to human and cotton‐top tamarins (Saguinus oedipus), there have been no appropriate animal models until the lymphoma model induced by EBV in human peripheral blood lymphocyte (hu‐PBL)/SCID chimeric mice was reported. However, it is still controversial whether the EBV‐associated lymphoma induced in hu‐PBL/SCID mice is a monoclonal tumor. In this study, we transplanted normal human peripheral blood lymphocytes (hu‐PBL) from six donors infected with EBV into SCID mice to construct hu‐PBL/SCID chimeric mice. The induced tumors were found in the mediastinum or abdominal cavity of SCID mice. Microscopic observation exhibited tumor cells that were large and had a plasmablastic, centroblastic or immunoblastic‐like appearance. Immunophenotyping assays showed the induced tumors were LCA‐positive, CD20/CD79a‐positive (markers of B cells), and CD3/CD45RO‐negative (markers of T cells). A human‐specific Alu sequence could be amplified by Alu‐PCR. This confirmed that induced tumors were B‐cell lymphomas originating from the transplanted human lymphocytes rather than mouse cells. EBER in situ hybridization detected positive signals in the nuclei of the tumor cells. Expression of EBV‐encoded LMP1, EBNA‐1, and EBNA‐2 in the tumors was significantly positive. PCR‐based capillary electrophoresis analysis of IgH gene rearrangement revealed a monoclonal peak and single amplification product in all six cases of induced tumors. This indicated that EBV can induce monoclonal proliferation of human B lymphocytes and promotes the development of lymphoma. J. Med. Virol. 88:1804–1813, 2016. © 2016 Wiley Periodicals, Inc.