Dynamic viral integration patterns actively participate in the progression of BK polyomavirus-associated diseases after renal transplantation.

The classical lytic infection theory along with large T antigen-mediated oncogenesis cannot explain the BK polyomavirus (BKPyV)-associated tumor secondary to BKPyV-associated nephropathy (BKVAN), viremia/DNAemia, and viruria after renal transplantation. This study performed virome capture sequencing and pathological examination on regularly collected urine sediment and peripheral blood samples, and BKVAN and tumor biopsy tissues of 20 patients with BKPyV-associated diseases of different stages. In the early noncancerous stages, well-amplified integration sites were visualized by in situ polymerase chain reaction, simultaneously with BKPyV inclusion bodies and capsid protein expression. The integration intensity, the proportion of microhomology-mediated end-joining integration, and host PARP-1 and POLQ gene expression levels increased with disease progression. Furthermore, multiomics analysis was performed on BKPyV-associated urothelial carcinoma tissues, identifying tandem-like structures of BKPyV integration using long-read genome sequencing. The carcinogenicity of BKPyV integration was proven to disturb host gene expression and increase viral oncoprotein expression. Fallible DNA double-strand break repair pathways were significantly activated in the parenchyma of BKPyV-associated tumors. Olaparib showed an antitumor activity dose-response effect in the tumor organoids without BRCA1/2 genes mutation. In conclusion, the dynamic viral integration patterns actively participate in the progression of BKPyV-associated diseases and thus could be a potential target for disease monitoring and intervention.

Viral integration in BK polyomavirus-associated urothelial carcinoma in renal transplant recipients: multistage carcinogenesis revealed by next-generation virome capture sequencing.

BK polyomavirus (BKPyV)-associated cancer after transplantation has gained increasing attention. However, the role of BKPyV integration on oncogenesis is still unclear. In this study, next-generation virome capture sequencing of primary and metastatic tumors were performed in three patients with BKPyV-associated urothelial carcinoma after renal transplantation. As a result, a total of 332 viral integration sites were identified in the six tumors. Integration of BKPyV in both primary and metastatic tumors followed the mechanism of microhomology-mediated end joining mostly, since microhomologies between human and BKPyV genomes were significantly enriched in flanking regions of 84% of the integration sites. Viral DNA breakpoints were nonrandom and tended to assemble in large T gene, small T gene and viral protein 2 gene. There were three, one and one consensus integration sites between the primary and metastatic tumors, which affected LINC01924, eIF3c, and NEIL2 genes in the three cases respectively. Thus, we concluded that integration of BKPyV was a continuous process occurring in both primary and metastatic tumors, generating heterogenous tumor cell populations. Through this ongoing process, certain cell populations might have gained growth advantage or metastatic potential, as a result of viral integration either affecting the cellular genes where the viral DNA integrated to or altering the expression or function of the viral genes.