Angelo Taronna, Elisa Mazzoni, Antonio D'Agostino, Fernanda Martini, Massimo Bovenzi, Giovanni Rezza, Francesco Lupidi, Massimo Gerosa, Giuseppe Barbanti-Brodano, Giuseppina Ruggeri, John Charles Rotondo, Mauro Tognon, Alfredo Corallini, Ferruccio Casali, Mazzoni, E, Gerosa, M, Lupidi, F, Corallini, A, Taronna, Ap, D’Agostino, A, Bovenzi, Massimo, Ruggeri, G, Casali, F, Rotondo, Jc, Rezza, G, Barbanti Brodano, G, Tognon, M, and Martini, F.
Glioblastoma multiforme (GBM) is the most severe form of cancer among gliomas. Indeed, GBM is a World Health Organization grade IV tumor of the CNS, with a mean survival time of 0.5 years.1 Its incidence is ∼1/100 000, which represents 30% of all CNS malignancies.2 According to the recent Eurocare 3 report,3 the mean age of patients affected by glioblastoma is 66 years. The extremely grim prognosis of GBM patients probably explains why such a rare tumor accounts for 2% of all cancer-related deaths in both Europe and the United States.4 GBM is characterized by high genotypic and phenotypic heterogeneities, but it is invariably and homogeneously resistant to conventional chemo/radiotherapy.1 The vast majority (95%) of GBM is represented by primary de novo glioblastomas.5 GBM is considered, like other tumors, a genetic disease of the somatic cell due to an impressive series of alterations of the cellular genome, such as point mutations, gene amplifications, translocations, and deletions, as well as epigenetic modifications, including methylation of specific genes. A limited percentage (5%) of GBM is linked to genetic predispositions, which are mainly associated with rare hereditary syndromes, such as Li–Fraumeni syndrome, Turcot syndrome, Peutz–Jegher syndrome, and neurofibromatosis 1 and 2.2 Exposure to chemical and physical carcinogenic agents, the genetic predisposition, and/or infections by oncogenic viruses, including simian virus 40 (SV40), have been repeatedly advocated in the literature.6,7 SV40 is a nonenveloped small DNA virus of ∼5.2 kb in size. SV40 was recognized in the 1960s as a contaminant of both inactivated (Salk) and live attenuated (Sabin) antipoliomyelitis vaccines. As a consequence, SV40 was inadvertently administered to human populations worldwide mainly by antipoliomyelitis vaccines, produced in SV40 naturally infected monkey kidney cells. Soon after its isolation, SV40 was characterized as a transforming and tumorigenic viral agent.6,7 Cell transformation and tumorigenesis by SV40 is induced by 2 oncoproteins, the large T antigen (Tag) and the small t antigen (tag), which target key cellular proteins, such as the tumor suppressor p53 and retinoblastoma family proteins, inactivating their functions.6,8 This small DNA tumor virus was found to be associated with some human cancers, including GBM. SV40 footprints were detected at high prevalence in GBM specimens, but SV40 sequences have also been revealed, although at lower prevalence, in blood specimens from healthy donors.9–11 In this context it is worth recalling that other investigations did not find SV40 footprints in human brain tumor specimens12,13 or higher SV40 antibodies in serum samples from brain tumor patients than in normal individuals.14 It has been reported that SV40-negative data on human tumor samples obtained by some groups were affected by technical flaws that invalidate the conclusions.15–17 A considerable debate, because of these contrasting reports, has developed in the scientific community.6,7 SV40 antibody detection had been performed in most cases using serologic methods with SV40 virus-like particles, but due to the high protein homology among the 3 main polyomaviruses—SV40, BKV, and JCV—final results were always influenced by some cross-reactivity.18–24 Altogether these reports prompted us to use an indirect ELISA with synthetic peptides employed as specific mimotopes, mimicking SV40 viral capsid antigens. Indeed, recent investigations have reported on the development of a specific and sensitive serologic test for SV40. The test is based on an indirect ELISA employing synthetic peptides as mimotopes/antigens of SV40 viral capsid proteins (VPs), without cross-reactivity with other closely related human polyomaviruses, such as BKV and JCV.25–28 This immunologic assay was used to detect specific serum antibodies against SV40 VPs in normal individuals of different ages and oncologic patients affected by malignant pleural mesothelioma and breast cancer (BC).25–28 In this investigation, serum samples from GBM patients were comparatively analyzed for the presence and titer of antibodies against SV40 infection, with serum samples from healthy individuals and from other reliable controls. No other slow virus infections were investigated.