@article{SbieraKircherAltierietal.2021, author = {Sbiera, Iuliu and Kircher, Stefan and Altieri, Barbara and Fassnacht, Martin and Kroiss, Matthias and Sbiera, Silviu}, title = {Epithelial and Mesenchymal Markers in Adrenocortical Tissues: How Mesenchymal Are Adrenocortical Tissues?}, series = {Cancers}, volume = {13}, journal = {Cancers}, number = {7}, issn = {2072-6694}, doi = {10.3390/cancers13071736}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236486}, year = {2021}, abstract = {A clinically relevant proportion of adrenocortical carcinoma (ACC) cases shows a tendency to metastatic spread. The objective was to determine whether the epithelial to mesenchymal transition (EMT), a mechanism associated with metastasizing in several epithelial cancers, might play a crucial role in ACC. 138 ACC, 29 adrenocortical adenomas (ACA), three normal adrenal glands (NAG), and control tissue samples were assessed for the expression of epithelial (E-cadherin and EpCAM) and mesenchymal (N-cadherin, SLUG and SNAIL) markers by immunohistochemistry. Using real-time RT-PCR we quantified the alternative isoform splicing of FGFR 2 and 3, another known indicator of EMT. We also assessed the impact of these markers on clinical outcome. Results show that both normal and neoplastic adrenocortical tissues lacked expression of epithelial markers but strongly expressed mesenchymal markers N-cadherin and SLUG. FGFR isoform splicing confirmed higher similarity of adrenocortical tissues to mesenchymal compared to epithelial tissues. In ACC, higher SLUG expression was associated with clinical markers indicating aggressiveness, while N-cadherin expression inversely associated with these markers. In conclusion, we could not find any indication of EMT as all adrenocortical tissues lacked expression of epithelial markers and exhibited closer similarity to mesenchymal tissues. However, while N-cadherin might play a positive role in tissue structure upkeep, SLUG seems to be associated with a more aggressive phenotype.}, language = {en} } @article{DoghmanBouguerraFinettiDurandetal.2020, author = {Doghman-Bouguerra, Mabrouka and Finetti, Pascal and Durand, Nelly and Parise, Ivy Zort{\´e}a S. and Sbiera, Silviu and Cantini, Giulia and Canu, Letizia and Hescot, S{\´e}gol{\`e}ne and Figueiredo, Mirna M. O. and Komechen, Heloisa and Sbiera, Iuliu and Nesi, Gabriella and Paci, Angelo and Al Ghuzlan, Abir and Birnbaum, Daniel and Baudin, Eric and Luconi, Michaela and Fassnacht, Martin and Figueiredo, Bonald C. and Bertucci, Fran{\c{c}}ois and Lalli, Enzo}, title = {Cancer-testis antigen FATE1 expression in adrenocortical tumors is associated with a pervasive autoimmune response and is a marker of malignancy in adult, but not children, ACC}, series = {Cancers}, volume = {12}, journal = {Cancers}, number = {3}, issn = {2072-6694}, doi = {10.3390/cancers12030689}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203211}, year = {2020}, abstract = {The SF-1 transcription factor target gene FATE1 encodes a cancer-testis antigen that has an important role in regulating apoptosis and response to chemotherapy in adrenocortical carcinoma (ACC) cells. Autoantibodies directed against FATE1 were previously detected in patients with hepatocellular carcinoma. In this study, we investigated the prevalence of circulating anti-FATE1 antibodies in pediatric and adult patients with adrenocortical tumors using three different methods (immunofluorescence, ELISA and Western blot). Our results show that a pervasive anti-FATE1 immune response is present in those patients. Furthermore, FATE1 expression is a robust prognostic indicator in adult patients with ACC and is associated with increased steroidogenic and decreased immune response gene expression. These data can open perspectives for novel strategies in ACC immunotherapy.}, language = {en} } @article{EckhardtSbieraKrebsetal.2022, author = {Eckhardt, Carolin and Sbiera, Iuliu and Krebs, Markus and Sbiera, Silviu and Spahn, Martin and Kneitz, Burkhard and Joniau, Steven and Fassnacht, Martin and K{\"u}bler, Hubert and Weigand, Isabel and Kroiss, Matthias}, title = {High expression of Sterol-O-Acyl transferase 1 (SOAT1), an enzyme involved in cholesterol metabolism, is associated with earlier biochemical recurrence in high risk prostate cancer}, series = {Prostate Cancer and Prostatic Diseases}, volume = {25}, journal = {Prostate Cancer and Prostatic Diseases}, number = {3}, issn = {1476-5608}, doi = {10.1038/s41391-021-00431-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-271819}, pages = {484-490}, year = {2022}, abstract = {Background Prostate cancer (PCa) is the most frequent cancer in men. The prognosis of PCa is heterogeneous with many clinically indolent tumors and rare highly aggressive cases. Reliable tissue markers of prognosis are lacking. Active cholesteryl ester synthesis has been associated with prostate cancer aggressiveness. Sterol-O-Acyl transferases (SOAT) 1 and 2 catalyze cholesterol esterification in humans. Objective To investigate the value of SOAT1 and SOAT2 tissue expression as prognostic markers in high risk PCa. Patients and Methods Formalin-fixed paraffin-embedded tissue samples from 305 high risk PCa cases treated with radical prostatectomy were analyzed for SOAT1 and SOAT2 protein expression by semi-quantitative immunohistochemistry. The Kaplan-Meier method and Cox proportional hazards modeling were used to compare outcome. Main Outcome Measure Biochemical recurrence (BCR) free survival. Results SOAT1 expression was high in 73 (25\%) and low in 219 (75\%; not evaluable: 13) tumors. SOAT2 was highly expressed in 40 (14\%) and at low levels in 249 (86\%) samples (not evaluable: 16). By Kaplan-Meier analysis, we found significantly shorter median BCR free survival of 93 months (95\% confidence interval 23.6-123.1) in patients with high SOAT1 vs. 134 months (112.6-220.2, Log-rank p < 0.001) with low SOAT1. SOAT2 expression was not significantly associated with BCR. After adjustment for age, preoperative PSA, tumor stage, Gleason score, resection status, lymph node involvement and year of surgery, high SOAT1 but not SOAT2 expression was associated with shorter BCR free survival with a hazard ratio of 2.40 (95\% CI 1.57-3.68, p < 0.001). Time to clinical recurrence and overall survival were not significantly associated with SOAT1 and SOAT2 expression CONCLUSIONS: SOAT1 expression is strongly associated with BCR free survival alone and after multivariable adjustment in high risk PCa. SOAT1 may serve as a histologic marker of prognosis and holds promise as a future treatment target.}, language = {en} } @article{SbieraKircherAltierietal.2021, author = {Sbiera, Iuliu and Kircher, Stefan and Altieri, Barbara and Lenz, Kerstin and Hantel, Constanze and Fassnacht, Martin and Sbiera, Silviu and Kroiss, Matthias}, title = {Role of FGF Receptors and Their Pathways in Adrenocortical Tumors and Possible Therapeutic Implications}, series = {Frontiers in Endocrinology}, volume = {12}, journal = {Frontiers in Endocrinology}, issn = {1664-2392}, doi = {10.3389/fendo.2021.795116}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-251953}, year = {2021}, abstract = {Adrenocortical carcinoma (ACC) is a rare endocrine malignancy and treatment of advanced disease is challenging. Clinical trials with multi-tyrosine kinase inhibitors in the past have yielded disappointing results. Here, we investigated fibroblast growth factor (FGF) receptors and their pathways in adrenocortical tumors as potential treatment targets. We performed real-time RT-PCR of 93 FGF pathway related genes in a cohort of 39 fresh frozen benign and malignant adrenocortical, 9 non-adrenal tissues and 4 cell lines. The expression of FGF receptors was validated in 166 formalin-fixed paraffin embedded (FFPE) tissues using RNA in situ hybridization (RNAscope) and correlated with clinical data. In malignant compared to benign adrenal tumors, we found significant differences in the expression of 16/94 FGF receptor pathway related genes. Genes involved in tissue differentiation and metastatic spread through epithelial to mesechymal transition were most strongly altered. The therapeutically targetable FGF receptors 1 and 4 were upregulated 4.6- and 6-fold, respectively, in malignant compared to benign adrenocortical tumors, which was confirmed by RNAscope in FFPE samples. High expression of FGFR1 and 4 was significantly associated with worse patient prognosis in univariate analysis. After multivariate adjustment for the known prognostic factors Ki-67 and ENSAT tumor stage, FGFR1 remained significantly associated with recurrence-free survival (HR=6.10, 95\%CI: 1.78 - 20.86, p=0.004) and FGFR4 with overall survival (HR=3.23, 95\%CI: 1.52 - 6.88, p=0.002). Collectively, our study supports a role of FGF pathways in malignant adrenocortical tumors. Quantification of FGF receptors may enable a stratification of ACC for the use of FGFR inhibitors in future clinical trials.}, language = {en} } @article{LandwehrAltieriSchreineretal.2020, author = {Landwehr, Laura-Sophie and Altieri, Barbara and Schreiner, Jochen and Sbiera, Iuliu and Weigand, Isabel and Kroiss, Matthias and Fassnacht, Martin and Sbiera, Silviu}, title = {Interplay between glucocorticoids and tumor-infiltrating lymphocytes on the prognosis of adrenocortical carcinoma}, series = {Journal for ImmunoTherapy of Cancer}, volume = {8}, journal = {Journal for ImmunoTherapy of Cancer}, doi = {10.1136/jitc-2019-000469}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229893}, year = {2020}, abstract = {Background Adrenocortical carcinoma (ACC) is a rare endocrine malignancy. Tumor-related glucocorticoid excess is present in similar to 60\% of patients and associated with particularly poor prognosis. Results of first clinical trials using immune checkpoint inhibitors were heterogeneous. Here we characterize tumor-infiltrating T lymphocytes (TILs) in ACC in association with glucocorticoids as potential explanation for resistance to immunotherapy. Methods We performed immunofluorescence analysis to visualize tumor-infiltrating T cells (CD3\(^+\)), T helper cells (CD3\(^+\)CD4\(^+\)), cytotoxic T cells (CD3\(^+\)CD8\(^+\)) and regulatory T cells (Tregs; CD3\(^+\)CD4\(^+\)FoxP3\(^+\)) in 146 ACC tissue specimens (107 primary tumors, 16 local recurrences, 23 metastases). Quantitative data of immune cell infiltration were correlated with clinical data (including glucocorticoid excess). Results 86.3\% of ACC specimens showed tumor infiltrating T cells (7.7 cells/high power field (HPF)), including T helper (74.0\%, 6.7 cells/HPF), cytotoxic T cells (84.3\%, 5.7 cells/HPF) and Tregs (49.3\%, 0.8 cells/HPF). The number of TILs was associated with better overall survival (HR for death: 0.47, 95\% CI 0.25 to 0.87), which was true for CD4\(^+\)- and CD8\(^+\) subpopulations as well. In localized, non-metastatic ACC, the favorable impact of TILs on overall and recurrence-free survival was manifested even independently of ENSAT (European Network for the Study of Adrenal Tumors) stage, resection status and Ki67 index. T helper cells were negatively correlated with glucocorticoid excess (Phi=-0.290, p=0.009). Patients with glucocorticoid excess and low TILs had a particularly poor overall survival (27 vs. 121 months in patients with TILs without glucocorticoid excess). Conclusion Glucocorticoid excess is associated with T cell depletion and unfavorable prognosis. To reactivate the immune system in ACC by checkpoint inhibitors, an inhibition of adrenal steroidogenesis might be pivotal and should be tested in prospective studies.}, language = {en} } @article{TamburelloAltieriSbieraetal.2022, author = {Tamburello, Mariangela and Altieri, Barbara and Sbiera, Iuliu and Sigala, Sandra and Berruti, Alfredo and Fassnacht, Martin and Sbiera, Silviu}, title = {FGF/FGFR signaling in adrenocortical development and tumorigenesis: novel potential therapeutic targets in adrenocortical carcinoma}, series = {Endocrine}, volume = {77}, journal = {Endocrine}, number = {3}, doi = {10.1007/s12020-022-03074-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324420}, pages = {411-418}, year = {2022}, abstract = {FGF/FGFR signaling regulates embryogenesis, angiogenesis, tissue homeostasis and wound repair by modulating proliferation, differentiation, survival, migration and metabolism of target cells. Understandably, compelling evidence for deregulated FGF signaling in the development and progression of different types of tumors continue to emerge and FGFR inhibitors arise as potential targeted therapeutic agents, particularly in tumors harboring aberrant FGFR signaling. There is first evidence of a dual role of the FGF/FGFR system in both organogenesis and tumorigenesis, of which this review aims to provide an overview. FGF-1 and FGF-2 are expressed in the adrenal cortex and are the most powerful mitogens for adrenocortical cells. Physiologically, they are involved in development and maintenance of the adrenal gland and bind to a family of four tyrosine kinase receptors, among which FGFR1 and FGFR4 are the most strongly expressed in the adrenal cortex. The repeatedly proven overexpression of these two FGFRs also in adrenocortical cancer is thus likely a sign of their participation in proliferation and vascularization, though the exact downstream mechanisms are not yet elucidated. Thus, FGFRs potentially offer novel therapeutic targets also for adrenocortical carcinoma, a type of cancer resistant to conventional antimitotic agents.}, language = {en} } @article{SbieraDexneitReichardtetal.2011, author = {Sbiera, Silviu and Dexneit, Thomas and Reichardt, Sybille D. and Michel, Kai D. and van den Brandt, Jens and Schmull, Sebastian and Kraus, Luitgard and Beyer, Melanie and Mlynski, Robert and Wortmann, Sebastian and Allolio, Bruno and Reichardt, Holger M. and Fassnacht, Martin}, title = {Influence of Short-Term Glucocorticoid Therapy on Regulatory T Cells \(In\) \(Vivo\)}, series = {PLoS One}, volume = {6}, journal = {PLoS One}, number = {9}, doi = {10.1371/journal.pone.0024345}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140822}, pages = {e24345}, year = {2011}, abstract = {Background: Pre- and early clinical studies on patients with autoimmune diseases suggested that induction of regulatory T(T(reg)) cells may contribute to the immunosuppressive effects of glucocorticoids(GCs). Objective: We readdressed the influence of GC therapy on T(reg) cells in immunocompetent human subjects and naive mice. Methods: Mice were treated with increasing doses of intravenous dexamethasone followed by oral taper, and T(reg) cells in spleen and blood were analyzed by FACS. Sixteen patients with sudden hearing loss but without an inflammatory disease received high-dose intravenous prednisolone followed by stepwise dose reduction to low oral prednisolone. Peripheral blood T(reg) cells were analyzed prior and after a 14 day GC therapy based on different markers. Results: Repeated GC administration to mice for three days dose-dependently decreased the absolute numbers of T(reg) cells in blood (100 mg dexamethasone/kg body weight: 2.8 +/- 1.8 x 10(4) cells/ml vs. 33 +/- 11 x 10(4) in control mice) and spleen (dexamethasone: 2.8 +/- 1.9 x 10(5)/spleen vs. 95 +/- 22 x 10(5)/spleen in control mice), which slowly recovered after 14 days taper in spleen but not in blood. The relative frequency of FOXP3(+) T(reg) cells amongst the CD4(+) T cells also decreased in a dose dependent manner with the effect being more pronounced in blood than in spleen. The suppressive capacity of T(reg) cells was unaltered by GC treatment in vitro. In immunocompetent humans, GCs induced mild T cell lymphocytosis. However, it did not change the relative frequency of circulating T(reg) cells in a relevant manner, although there was some variation depending on the definition of the T(reg) cells (FOXP3(+): 4.0 +/- 1.5\% vs 3.4 +/- 1.5\%*; AITR(+): 0.660.4 vs 0.5 +/- 0.3\%, CD127(low): 4.0 +/- 1.3 vs 5.0 +/- 3.0\%* and CTLA4+: 13.8 +/- 11.5 vs 15.6 +/- 12.5\%; * p < 0.05). Conclusion: Short-term GC therapy does not induce the hitherto supposed increase in circulating T(reg) cell frequency, neither in immunocompetent humans nor in mice. Thus, it is questionable that the clinical efficacy of GCs is achieved by modulating T(reg) cell numbers.}, language = {en} } @article{SbieraTryfonidouWeigandetal.2016, author = {Sbiera, Silviu and Tryfonidou, Marianna A. and Weigand, Isabel and Grinwis, Guy C. M. and Broeckx, Bart and Herterich, Sabine and Allolio, Bruno and Deutschbein, Timo and Fassnacht, Martin and Meij, Bj{\"o}rn P.}, title = {Lack of Ubiquitin Specific Protease 8 (USP8) Mutations in Canine Corticotroph Pituitary Adenomas}, series = {Plos One}, volume = {11}, journal = {Plos One}, number = {12}, doi = {10.1371/journal.pone.0169009}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148020}, pages = {e0169009}, year = {2016}, abstract = {Purpose Cushing's disease (CD), also known as pituitary-dependent hyperadrenocorticism, is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary tumours. Affected humans and dogs have similar clinical manifestations, however, the incidence of the canine disease is thousand-fold higher. This makes the dog an obvious model for studying the pathogenesis of pituitary-dependent hyperadrenocorticism. Despite certain similarities identified at the molecular level, the question still remains whether the two species have a shared oncogenetic background. Recently, hotspot recurrent mutations in the gene encoding for ubiquitin specific protease 8 (USP8) have been identified as the main driver behind the formation of ACTH-secreting pituitary adenomas in humans. In this study, we aimed to verify whether USP8 mutations also play a role in the development of such tumours in dogs. Methods Presence of USP8 mutations was analysed by Sanger and PCR-cloning sequencing in 38 canine ACTH-secreting adenomas. Furthermore, the role of USP8 and EGFR protein expression was assessed by immunohistochemistry in a subset of 25 adenomas. Results None of the analysed canine ACTH-secreting adenomas presented mutations in the USP8 gene. In a subset of these adenomas, however, we observed an increased nuclear expression of USP8, a phenotype characteristic for the USP8 mutated human tumours, that correlated with smaller tumour size but elevated ACTH production in those tumours. Conclusions Canine ACTH-secreting pituitary adenomas lack mutations in the USP8 gene suggesting a different genetic background of pituitary tumourigenesis in dogs. However, elevated nuclear USP8 protein expression in a subset of tumours was associated with a similar phenotype as in their human counterparts, indicating a possible end-point convergence of the different genetic backgrounds in the two species. In order to establish the dog as a useful animal model for the study of CD, further comprehensive studies are needed.}, language = {en} } @article{AltieriSbieraDellaCasaetal.2017, author = {Altieri, Barbara and Sbiera, Silviu and Della Casa, Silvia and Weigand, Isabel and Wild, Vanessa and Steinhauer, Sonja and Fadda, Guido and Kocot, Arkadius and Bekteshi, Michaela and Mambretti, Egle M. and Rosenwald, Andreas and Pontecorvi, Alfredo and Fassnacht, Martin and Ronchi, Cristina L.}, title = {Livin/BIRC7 expression as malignancy marker in adrenocortical tumors}, series = {Oncotarget}, volume = {8}, journal = {Oncotarget}, number = {6}, doi = {10.18632/oncotarget.14067}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171887}, pages = {9323-9338}, year = {2017}, abstract = {Livin/BIRC7 is a member of the inhibitors of apoptosis proteins family, which are involved in tumor development through the inhibition of caspases. Aim was to investigate the expression of livin and other members of its pathway in adrenocortical tumors and in the adrenocortical carcinoma (ACC) cell line NCI-H295R. The mRNA expression of livin, its isoforms α and β, XIAP, CASP3 and DIABLO was evaluated by qRT-PCR in 82 fresh-frozen adrenal tissues (34 ACC, 25 adenomas = ACA, 23 normal adrenal glands = NAG). Livin protein expression was assessed by immunohistochemistry in 270 paraffin-embedded tissues (192 ACC, 58 ACA, 20 NAG). Livin, CASP3 and cleaved caspase-3 were evaluated in NCI-H295R after induction of livin overexpression. Relative livin mRNA expression was significantly higher in ACC than in ACA and NAG (0.060 ± 0.116 vs 0.004 ± 0.014 and 0.002 ± 0.009, respectively, p < 0.01), being consistently higher in tumors than in adjacent NAG and isoform β more expressed than α. No significant differences in CASP3, XIAP and DIABLO levels were found among these groups. In immunohistochemistry, livin was localized in both cytoplasm and nuclei. The ratio between cytoplasmic and nuclear staining was significantly higher in ACC (1.51 ± 0.66) than in ACA (0.80 ± 0.35) and NAG (0.88 ± 0.27; p < 0.0001). No significant correlations were observed between livin expression and histopathological parameters or clinical outcome. In NCI-H295R cells, the livin overexpression slightly reduced the activation of CASP3, but did not correlate with cell viability. In conclusion, livin is specifically over-expressed in ACC, suggesting that it might be involved in adrenocortical tumorigenesis and represent a new molecular marker of malignancy.}, language = {en} } @phdthesis{Sbiera2012, author = {Sbiera, Silviu}, title = {Interaction of Human Polyomavirus JC with cells of the hematopoietic system in the periphery}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-74183}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {Primary contact with human polyomaviruses is followed by lifelong asymptomatic persistence of viral DNA. Under severe immunosuppression JCV activation may lead to unrestricted virus growth in the CNS followed by development of progressive multifocal leukoencephalopathy (PML). Besides the kidney and the brain, target cells of persistent infection were also found in the hematopoietic system. This included the presence of JCV genomes in peripheral blood cells (PBCs). In the attempt to understand the role of PBCs for the JCV infection in humans, we asked for the type of cells affected as well as for virus interaction with PBCs. Analysis of separated subpopulations by highly sensitive and specific polymerase chain reaction and Southern blot hybridization revealed the presence of JCV DNA mostly in circulating granulocytes. These cells have important functions in innate immunity and are professional phagocytes. This suggested that PCR amplified DNA might be the result of an extranuclear association of the virus due to membrane attachment or phagocytosis rather than JCV infection with presence of viral DNA in the nucleus. In the attempt to answer this question JCV DNA was subcellularly localized in the blood of 22 healthy donors by JCV specific fluorescence in situ hybridization (FISH). Granulocytes and peripheral blood mononuclear cells (PBMCs) were separated by Percoll gradient centrifugation. Intracellular JCV DNA was hybridized with Digoxigenin-labeled JCV specific DNA probes covering half of the viral genome. As the sensitivity of the anti-digoxigenin antibody system was lower than the PCR detection level, a chemical amplification step was included consisting of peroxidase labeled secondary antibody precipitating biotinylated tyramide followed by detection with streptavidin-Texas-Red and fluorescence microscopy. Comparison of the number of cells affected in healthy individuals with 15 HIV-1 infected patients with and without PML revealed that the rate of affected PBMCs was comparable in both groups (2.5±0.4 and 14.5±0.9 per 1000). In contrast, the rate of JCV positive granulocytes in the immunosuppressed group was 92.6±1.7\% compared to 4±1.4\% in healthy donors thus confirming that granulocytes are the major group of circulating cells affected by JCV and that HIV-1 associated immune impairment has an important effect on the virus-cell association. Localization revealed that JCV DNA was predominantly located within the cytoplasm, although hybridizing signals occasionally covered the nuclear compartment. The fluorescent glow of chemical amplification combined with classical fluorescence microscopy did not allow an unequivocal localization of viral DNA. However, confocal microscopy of 24 sections through single cells combined with FISH without chemical amplification confirmed cytoplasmic localization of JCV DNA in a large number of cells. Additionally, it clearly demonstrated that JCV DNA was also located in the nucleus and nuclear localization directly correlated with the number of cells affected. Calculation of the virus load in subcellular compartments revealed that up to 50\% of the JCV genomes were located in the nucleus thus pointing to viral infection at least in the granulocytes of HIV-1 infected patients. This may contribute to the distribution of the virus from sites of peripheral infection to the CNS and may promote the development of active PML in the severely immune impaired patients.}, subject = {Polyomaviren}, language = {en} }