Detection of infectious simian immunodeficiency virus in B- and T-cell lymphomas of experimentally infected macaques.

An increasing frequency of malignant lymphomas occurs among patients infected by human immunodeficiency virus. Because of the close similarities to human malignancies, we used a nonhuman primate model to study the pathogenesis of simian immunodeficiency virus (SIV)–associated malignancies. Specifically, we investigated (1) the presence of the SIV genome in tumor cells, (2) the presence of coinfecting viruses, and (3) the presence of a rearrangement of the immunoglobulin and c-myc genes. We observed 5 cases of non-Hodgkin's lymphomas (4 of B- and 1 of T-cell origin) among 14 SIV-infected cynomolgus monkeys. No c-myc translocation was observed in the tumors, whereas B-cell lymphomas were characterized either by a monoclonal (in 2 of 4) or by an oligoclonal (in 2 of 4) VDJ rearrangements of the immunoglobulin heavy chain gene. Molecular, biological, and immunological analyses did show the presence of infectious SIV in the tumor cells of 1 T-cell and 2 oligoclonal B-cell lymphomas. Neither Simian T-lymphotropic nor Epstein-Barr viruses were detectable, whereas Simian herpes virus Macaca fascicularis -1 was detectable at a very low copy number in 3 of 4 B-cell lymphomas; however, only 1 of these also harbored the SIV genome. These results support the possibility that SIV may be directly involved in the process of B or T lymphomagenesis occurring in simian acquired immunodeficiency syndrome.