Date Published: July 12, 2018
Publisher: Public Library of Science
Author(s): Vickie A. Marshall, Nazzarena Labo, Xing-Pei Hao, Benjamin Holdridge, Marshall Thompson, Wendell Miley, Catherine Brands, Vicky Coalter, Rebecca Kiser, Miriam Anver, Yelena Golubeva, Andrew Warner, Elaine S. Jaffe, Michael Piatak, Scott W. Wong, Claes Ohlen, Rhonda MacAllister, Jeremy Smedley, Claire Deleage, Gregory Q. Del Prete, Jeffrey D. Lifson, Jacob D. Estes, Denise Whitby, Dirk P. Dittmer.
Human gammaherpesviruses are associated with malignancies in HIV infected individuals; in macaques used in non-human primate models of HIV infection, gammaherpesvirus infections also occur. Limited data on prevalence and tumorigenicity of macaque gammaherpesviruses, mostly cross-sectional analyses of small series, are available. We comprehensively examine all three-rhesus macaque gammaherpesviruses -Rhesus rhadinovirus (RRV), Rhesus Lymphocryptovirus (RLCV) and Retroperitoneal Fibromatosis Herpesvirus (RFHV) in macaques experimentally infected with Simian Immunodeficiency Virus or Simian Human Immunodeficiency Virus (SIV/SHIV) in studies spanning 15 years at the AIDS and Cancer Virus Program of the Frederick National Laboratory for Cancer Research. We evaluated 18 animals with malignancies (16 lymphomas, one fibrosarcoma and one carcinoma) and 32 controls. We developed real time quantitative PCR assays for each gammaherpesvirus DNA viral load (VL) in malignant and non-tumor tissues; we also characterized the tumors using immunohistochemistry and in situ hybridization. Furthermore, we retrospectively quantified gammaherpesvirus DNA VL and SIV/SHIV RNA VL in longitudinally-collected PBMCs and plasma, respectively. One or more gammaherpesviruses were detected in 17 tumors; generally, one was predominant, and the relevant DNA VL in the tumor was very high compared to surrounding tissues. RLCV was predominant in tumors resembling diffuse large B cell lymphomas; in a Burkitt-like lymphoma, RRV was predominant; and in the fibrosarcoma, RFHV was predominant. Median RRV and RLCV PBMC DNA VL were significantly higher in cases than controls; SIV/SHIV VL and RLCV VL were independently associated with cancer. Local regressions showed that longitudinal VL patterns in cases and controls, from SIV infection to necropsy, differed for each gammaherpesvirus: while RFHV VL increased only slightly in all animals, RLCV and RRV VL increased significantly and continued to increase steeply in cases; in controls, VL flattened. In conclusion, the data suggest that gammaherpesviruses may play a significant role in tumorogenesis in macaques infected with immunodeficiency viruses.
The lymphotropic human gammaherpesviruses Epstein Barr Virus (EBV) and Kaposi’s Sarcoma-Associated Herpesvirus (KSHV) are associated with malignancies in the setting of HIV infection. EBV is associated with aggressive B cell Non-Hodgkin’s lymphomas such as diffuse large B cell lymphoma (DLBCL) and Burkitt’s lymphoma (BL), as well as classical Hodgkin’s lymphoma and other lymphoproliferative disorders. KSHV is associated with Kaposi’s sarcoma (KS), primary effusion lymphoma (PEL) and multicentric Castleman’s disease (MCD). While the incidence of AIDS-defining malignancies has declined since the introduction of potent anti-retroviral therapies, they still remain an important cause of morbidity and mortality in HIV infected persons [2, 3] and the risk of developing non-AIDS defining lymphomas and other malignancies is 2–3 fold higher in HIV infected individuals than in the general population [4, 5].
Infections with lymphotropic gammaherpesviruses are prevalent in rhesus macaques used in HIV research and yet are rarely evaluated, except in limited specific pathogen free colonies stringently bred, tested, and cared for to exclude these agents. In our retrospective study, antibodies to RLCV and RRV were present in >90% of cases and controls, while antibodies to RFHV were detected in 25% of the cases and 28% of the controls. These serological data are similar to previous reports from US primate centers [16–18]. Our objectives for this study, which was more extensive than most prior published surveys, and included longitudinal quantitative PCR analysis for all three rhesus herpesviruses as well as histologic (IHC/ISH) analysis comparing tumor tissue and corresponding non-tumor tissue, were to elucidate the potential role of naturally acquired gammaherpesviruses in malignancies occurring in SIV/SHIV infected macaques. We have found that most such malignancies were associated with RLCV, consistent with previous reports. [16, 17, 19]. We did observe however, a BL-like tumor with a very high RRV viral load, low or absent RFHV and RLCV, and IHC staining consistent with a RRV etiology. We also observed a fibrosarcoma in which immunohistochemistry and viral load in the tumor were consistent with an etiological role for RFHV. Thus, we show that all three gammaherpesviruses may have oncogenic potential in the setting of experimental SIV/SHIV infection. The histological classification of these malignancies observed in SIV/SHIV-infected macaques broadly resembles that of malignancies seen in HIV-infected persons.