Multiplex analysis of Human Polyomavirus diversity in kidney transplant recipients with BK virus replication

Background: While the pathogenicity of the two initially identified Human Polyomaviruses (HPyVs), BK Virus (BKPyV) and JC Virus (JCPyV) has been intensely studied, there is only limited data, on whether the occurrence of the recently discovered HPyVs correlates with high level BKPyV replication and progression towards Polyomavirus associated nephropathy (PVAN). Methods: Therefore, we performed a comprehensive longitudinal genoprevalence analysis of 13 HPyVs using a novel multiplex assay including 400 serum and 388 urine samples obtained from 99 kidney transplant recipients (KTRs), grouped by quantitative BKPyV DNA loads and evidence of manifest BKPyV associated disease (histologically verified PVAN, high urinary decoy cell levels and concurrent decrease of renal function). Results: In total, 3 different non-BKPyV/JCPyV HPyVs, Human Polyomavirus 9, Merkel Cell Polyomavirus (MCPyV) and Trichodysplasia Spinulosa associated Polyomavirus were detected in 11 blood and 21 urine samples from 21 patients. Although DNAemia of these viruses occurred more frequently during high level BKPyV DNAemia and PVAN, the increase of the detection frequency due to progression of BKPyV replication did not reach statistical significance for blood samples. The positive detection rate of MCPyV in urine, however, was significantly higher during BKPyV DNAemia in 19 KTRs of our cohort who suffered from histologically verified PVAN (p=0.005). In one individual with PVAN, continuous long-term shedding of MCPyV in urine was observed. Conclusion: In our cohort the recently discovered HPyVs HPyV9, TSPyV and MCPyV emerged in blood from KTRs with variable kinetics, while detection of MCPyV DNAuria occurred more frequently during BKPyV DNAemia in patients with PVAN.