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Next generation sequencing (NGS) can globally interrogate the genetic composition of biological samples in an unbiased yet sensitive manner. The objective of this study was to utilize the capabilities of NGS to investigate the reported association between glioblastoma multiforme (GBM) and human cytomegalovirus (HCMV). A large-scale comprehensive virome assessment was performed on publicly available sequencing datasets from the Cancer Genome Atlas (TCGA), including RNA-seq datasets from primary GBM (n = 157), recurrent GBM (n = 13), low-grade gliomas (n = 514), recurrent low-grade gliomas (n = 17), and normal brain (n = 5), and whole genome sequencing (WGS) datasets from primary GBM (n = 51), recurrent GBM (n = 10), and normal matched blood samples (n = 20). In addition, RNA-seq datasets from MRI-guided biopsies (n = 92) and glioma stem-like cell cultures (n = 9) were analyzed. Sixty-four DNA-seq datasets from 11 meningiomas and their corresponding blood control samples were also analyzed. Finally, three primary GBM tissue samples were obtained, sequenced using RNA-seq, and analyzed. After in-depth analysis, the most robust virus findings were the detection of papillomavirus (HPV) and hepatitis B reads in the occasional LGG sample (4 samples and 1 sample, respectively). In addition, low numbers of virus reads were detected in several datasets but detailed investigation of these reads suggest that these findings likely represent artifacts or non-pathological infections. For example, all of the sporadic low level HCMV reads were found to map to the immediate early promoter intimating that they likely originated from laboratory expression vector contamination. Despite the detection of low numbers of Epstein-Barr virus reads in some samples, these likely originated from infiltrating B-cells. Finally, human herpesvirus 6 and 7 aligned viral reads were identified in all DNA-seq and a few RNA-seq datasets but detailed analysis demonstrated that these were likely derived from the homologous human telomeric-like repeats. Other low abundance viral reads were detected in some samples but for most viruses, the reads likely represent artifacts or incidental infections. This analysis argues against associations between most known viruses and GBM or mengiomas. Nevertheless, there may be a low percentage association between HPV and/or hepatitis B and LGGs. [ABSTRACT FROM AUTHOR]

Background: Approximately 17 % of the human genome is comprised of the Long INterspersed Element-1 (LINE-1 or L1) retrotransposon, the only currently active autonomous family of retroelements. Though L1 elements have helped to shape mammalian genome evolution over millions of years, L1 activity can also be mutagenic and result in human disease. L1 expression has the potential to contribute to genomic instability via retrotransposition and DNA double-strand breaks (DSBs). Additionally, L1 is responsible for structural genomic variations induced by other transposable elements such as Alu and SVA, which rely on the L1 ORF2 protein for their propagation. Most of the genomic damage associated with L1 activity originates with the endonuclease domain of the ORF2 protein, which nicks the DNA in preparation for target-primed reverse transcription. Results: Bioinformatic analysis of full-length L1 loci residing in the human genome identified numerous mutations in the amino acid sequence of the ORF2 endonuclease domain. Some of these mutations were found in residues which were predicted to be phosphorylation sites for cellular kinases. We mutated several of these putative phosphorylation sites in the ORF2 endonuclease domain and investigated the effect of these mutations on the function of the full-length ORF2 protein and the endonuclease domain (ENp) alone. Most of the single and multiple point mutations that were tested did not significantly impact expression of the full-length ORF2p, or alter its ability to drive Alu retrotransposition. Similarly, most of those same mutations did not significantly alter expression of ENp, or impair its ability to induce DNA damage and cause toxicity. Conclusions: Overall, our data demonstrate that the full-length ORF2p or the ENp alone can tolerate several specific single and multiple point mutations in the endonuclease domain without significant impairment of their ability to support Alu mobilization or induce DNA damage, respectively. [ABSTRACT FROM AUTHOR]

Background The Epstein-Barr virus (EBV) is a causal agent in a number of malignancies in humans including hematopoietic tumors and non-hematopoietic tumors. Burkitt's lymphoma cell lines containing the Epstein-Barr virus have been shown to form tumors in nude mice while clonal derivatives of such cell lines in which the viral genome has been lost do not (JID 177: 1194- 1201, 1998; JV 72: 9150-9156, 1998; JV 68: 6069-6073, 1994). The re-introduction of EBV into these EBV negative BLs reconstitutes the tumor phenotype. Thus, EBV-induced cellular genes play critical role in EBV-related tumors. Methods and results In an attempt to identify cellular genes regulated by EBV that may contribute to its tumorigenic properties, we have enforced genome loss in the Burkitt's lymphoma (BL) line, MutuI, by introducing a dominant negative form of the episomal replication factor, EBNA1 and carried out gene array analysis. One of the genes identified by this analysis is PLAC1, a gene originally identified as being expressed exclusively in placental tissue. Real time RTPCR analysis verified higher expression in EBV positive vs. EBV negative Mutu clones. Analysis of a panel of RNAs from 20 normal tissues demonstrated the highest level of expression in placenta but significant expression was also observed in testis and brain cerebellum. PLAC1 expression was also observed in non-BL tumor cell lines derived from breast, ovary, and prostate. Lastly, expression of PLAC1 was found to be higher in some primary breast tumors compared to normal adjacent tissues. Conclusion This data suggests that the EBV-induced PLAC1 is a member of the cancer/testis group of tumor antigens. [ABSTRACT FROM AUTHOR]

Background: The Epstein-Barr virus (EBV) is a causal agent in a number of malignancies in humans including hematopoietic tumors and non-hematopoietic tumors. Burkitt's lymphoma cell lines containing the Epstein-Barr virus have been shown to form tumors in nude mice while clonal derivatives of such cell lines in which the viral genome has been lost do not (JID 177: 1194-1201, 1998; JV 72: 9150-9156, 1998; JV 68: 6069-6073, 1994). The re-introduction of EBV into these EBV negative BLs reconstitutes the tumor phenotype. Thus, EBV-induced cellular genes play critical role in EBV-related tumors., Methods and Results: In an attempt to identify cellular genes regulated by EBV that may contribute to its tumorigenic properties, we have enforced genome loss in the Burkitt's lymphoma (BL) line, MutuI, by introducing a dominant negative form of the episomal replication factor, EBNA1 and carried out gene array analysis. One of the genes identified by this analysis is PLAC1, a gene originally identified as being expressed exclusively in placental tissue. Real time RT-PCR analysis verified higher expression in EBV positive vs. EBV negative Mutu clones. Analysis of a panel of RNAs from 20 normal tissues demonstrated the highest level of expression in placenta but significant expression was also observed in testis and brain cerebellum. PLAC1 expression was also observed in non-BL tumor cell lines derived from breast, ovary, and prostate. Lastly, expression of PLAC1 was found to be higher in some primary breast tumors compared to normal adjacent tissues., Conclusion: This data suggests that the EBV-induced PLAC1 is a member of the cancer/testis group of tumor antigens.