Simian virus 40 and its association with human lymphomas

Simian Virus 40 Large T Antigen as a Model to Test the Efficacy of Flouroquinolones against Viral Helicases

Simian virus 40 large T-antigen (SV40 LT-Ag) is a 708 amino acid nuclear phosphoprotein. Among many functions of LT-Ag is its ability to perform as an ATPase-helicase, catalyzing the unwinding of viral genome during replication. The LT-Ag has been employed in the studies of helicase structure and function, and has served as a model helicase for the screening of antiviral drugs that target viral helicase. In this study, using in vitro enzyme assays and in silico computer modeling, we screened a batch of 18 fluoroquinolones to assess their potential as antivirals by virtue of their inhibition of the LT-Ag helicase. We found all fluoroquinolones to be inhibitory to the helicase activity of LT-Ag. In our docking analysis, most of these tested drugs showed similarity in their interactions with LT-Ag. Our study shows the potential of fluoroquinolones as antiviral drugs and of SV40 LT-Ag as a model protein for screening drugs against viral helicases.

SV40 Infection of Mesenchymal Stromal Cells From Wharton's Jelly Drives the Production of Inflammatory and Tumoral Mediators

The Mesenchymal Stromal Cells from umbilical cord Wharton's jelly (WJSCs) are a source of cells with high potentiality for the treatment of human immunological disorders. Footprints of the oncogenic viruses Simian Virus 40 (SV40) and JC Virus (JCPyV) have been recently detected in human WJSCs specimens. The aim of this study is to evaluate if WJSCs can be efficiently infected by these Polyomaviruses and if they can potentially exert tumoral activity. Cell culture experiments indicated that WJSCs could sustain both SV40 and JCPyV infections. A transient and lytic replication was observed for JCPyV, while SV40 persistently infected WJSCs over a long period of time, releasing a viral progeny at low titer without evident cytopathic effect (CPE). Considering the association between SV40 and human tumors and the reported ability of the oncogenic viruses to drive the host innate immune response to cell transformation, the expression profile of a large panel of immune mediators was evaluated in supernatants by the Bioplex platform. RANTES, IL-3, MIG, and IL-12p40, involved in chronic inflammation, cells differentiation, and transformation, were constantly measured at high concentration comparing to control. These findings represent a new aspect of SV40 biological activity in the humans, highlighting its interaction with specific host cellular pathways. In view of these results, it seems to be increasingly urgent to consider Polyomaviruses in the management of WJSCs for their safely use as promising therapeutic source. J. Cell. Physiol. 232: 3060-3066, 2017. © 2016 Wiley Periodicals, Inc.

Fanconi anemia patients are more susceptible to infection with tumor virus SV40

Fanconi anemia (FA) is a recessive DNA repair disease characterized by a high predisposition to developing neoplasms. DNA tumor polyomavirus simian virus 40 (SV40) transforms FA fibroblasts at high efficiency suggesting that FA patients could be highly susceptible to SV40 infection. To test this hypothesis, the large tumor (LT) antigen of SV40, BKV, JCV and Merkel Cell (MC) polyomaviruses were tested in blood samples from 89 FA patients and from 82 of their parents. Two control groups consisting of 47 no-FA patients affected by other genetic bone marrow failure diseases and 91 healthy subjects were also evaluated. Although JCV, BKV and MC were not found in any of the FA samples, the prevalence and viral load of SV40 were higher in FA patients (25%; mean viral load: 1.1×10² copies/10⁵cells) as compared with healthy individuals (4.3%; mean viral load: 0.8×10¹ copies/10⁵cells) and genetic controls (0%) (p<0.005). A marked age-dependent frequency of SV40 was found in FA with respect to healthy subjects suggesting that, although acquired early in life, the virus can widespread more easily in specific groups of population. From the analysis of family pedigrees, 60% of the parents of SV40-positive probands were positive for the virus compared to 2% of the parents of the SV40-negative probands (p<0.005). It is worthy of note that the relative frequency of SV40-positive relatives detected in this study was the highest ever reported, showing that asymptomatic FA carriers are also more susceptible to SV40. In conclusion, we favor the hypothesis that SV40 spread could be facilitated by individuals who are genetically more susceptible to infection, such as FA patients. The increased susceptibility to SV40 infection seems to be associated with a specific defect of the immune system which supports a potential interplay of SV40 with an underlying genetic alteration that increases the risk of malignancies.

The detection of CMV pp65 and IE1 in glioblastoma multiforme

Glioblastoma multiforme (GBM) is a highly lethal brain tumor affecting children and adults, with the majority of affected individuals dying from their disease by 2 years following diagnosis. Other groups have reported the association of cytomegalovirus (CMV) with GBM, and we sought to confirm these findings in a large series of patients with primary GBM from our institution. Immunohistochemical analysis of paraffin embedded tissue sections was performed on 49 newly diagnosed GBM tumors, the largest series reported to date. We confirmed the presence of CMV pp65 on 25/49 (51%) and of IE1 on 8/49 (16%) of these tumors. While pp65 and IE1 are generally found in the nucleus of cells that are permissibly infected by CMV, GBM in this series had mostly cytoplasmic staining, with only 16% having nuclear staining for one or both of these antigens. We infected GBM cell lines with a laboratory strain of CMV, and found that most of the staining was cytoplasmic, with some perinuclear localization of IE1. To test the potential for CMV infected GBM cells to be recognized by CMV pp65 and IE1 specific cytotoxic T lymphocytes (CTL), we used CMV infected GBM cell lines in cytotoxicity assays with human leukocyte antigen partially matched CMV CTL. Lysis of CMV infected GBM tumor cells was accentuated by pre-treating these cell lines with either the demethylating agent decitabine or interferon-γ, both of which were shown to increase MHC Class I and II expression on tumor cells in vitro. These studies confirm the presence of CMV pp65 or IE1 on approximately half of GBM, with the possibility that CMV positive tumor cells can be recognized by CMV pp65/IE1 specific T cells.

Does cytomegalovirus play a causative role in the development of various inflammatory diseases and cancer?

Human cytomegalovirus (HCMV) is a herpes virus that infects and is carried by 70-100% of the world's population. During its evolution, this virus has developed mechanisms that allow it to survive in an immunocompetent host. For many years, HCMV was not considered to be a major human pathogen, as it appeared to cause only rare cases of HCMV inclusion disease in neonates. However, HCMV is poorly adapted for survival in the immunosuppressed host and has emerged as an important human pathogen in AIDS patients and in patients undergoing immunosuppressive therapy following organ or bone marrow transplantation. HCMV-mediated disease in such patients has highlighted the possible role of this virus in the development of other diseases, in particular inflammatory diseases such as vascular diseases, autoimmune diseases and, more recently, with certain forms of cancers. Current research is focused on determining whether HCMV plays a causative role in these diseases or is merely an epiphenomenon of inflammation. Inflammation plays a central role in the pathogenesis of HCMV. This virus has developed a number of mechanisms that enable it to hide from the cells of the immune system and, at the same time, reactivation of a latent infection requires immune activation. Numerous products of the HCMV genome are devoted to control central functions of the innate and adaptive immune responses. By influencing the regulation of various cellular processes including the cell cycle, apoptosis and migration as well as tumour invasiveness and angiogenesis, HCMV may participate in disease development. Thus, the various drugs now available for treatment of HCMV disease (e.g. ganciclovir, acyclovir and foscarnet), may also prove to be useful in the treatment of other, more widespread diseases.