Cidofovir Inhibits Polyomavirus BK Replication in Human Renal Tubular Cells Downstream of Viral Early Gene Expression

Abstract

The human polyomavirus BK (BKV) causes nephropathy and hemorrhagic cystitis in kidney and bone marrow transplant patients, respectively. The anti-viral cidofovir (CDV) has been used in small case series but the effects on BKV replication are unclear, since polyomaviruses do not encode viral DNA polymerases. We investigated the effects of CDV on BKV(Dunlop) replication in primary human renal proximal tubule epithelial cells (RPTECs). CDV inhibited the generation of viral progeny in a dose-dependent manner yielding a 90% reduction at 40 lg/mL. Early steps such as receptor binding and entry seemed unaffected. Initial large T-antigen transcription and expression were also unaffected, but subsequent intra-cellular BKV DNA replication was reduced by >90%. Late viral mRNA and corresponding protein levels were also 90% reduced. In uninfected RPTECs, CDV 40 lg/mL reduced cellular DNA replication and metabolic activity by 7% and 11% in BrdU and WST-1 assays, respectively. BKV infection increased DNA replication to 142% and metabolic activity to 116%, respectively, which were reduced by CDV 40 lg/mL to levels of uninfected untreated RPTECs. Our results show that CDV inhibits BKV DNA replication downstream of large T-antigen expression and involves significant host cell toxicity. This should be considered in current treatment and drug development.

BK Polyomavirus Replication in Renal Tubular Epithelial Cells Is Inhibited by Sirolimus, but Activated by Tacrolimus Through a Pathway Involving FKBP-12

“…As described previously in detail 38, 39, BKPyV replication leads to a more than 100‐fold increase in supernatant viral loads in the burst phase at 72 hpi in mock‐treated cells, which was inhibited by SIR in a dose‐dependent fashion (inhibitory concentration 90 at 4 ng/mL; Figure 1A). Immunofluorescence staining demonstrated that SIR treatment at 4 ng/mL was associated with a lower number of BKPyV‐infected cells as shown for the LTag encoded in early viral gene region (EVGR) as well as for the cytoplasmic agnoprotein (Agno) or the nuclear major viral capsid protein Vp1 encoded in the late viral gene region (LVGR) (Figure 1B).…”

“…The stronger and longer‐lasting mTOR stimulation elicited by infectious virions argues for a contributory role of EVGR expression known to start after 6–12 hpi 38, 39. The Akt‐mTOR‐S6kinase activation and the time‐dependent mTOR inhibition suggest that host cell activation is important for uptake and efficient EVGR expression.…”

“…Thus, while the overall immunologic potency appears to be a plausible key component increasing the risk of BKPyV replication 35, 36, differences between immunosuppressive drugs might play an additional role 37. We therefore examined the direct virological effects of the mTOR inhibitor sirolimus (SIR) and of the calcineurin inhibitors TAC and CsA on BKPyV replication in a well‐characterized model of primary human proximal renal tubular epithelial cells (RPTECs), the primary target of BKPyV in the renal allograft 38, 39.…”

Relationship between clinical and BK virological response in patients with late hemorrhagic cystitis treated with cidofovir: a retrospective study from the European Group for Blood and Marrow Transplantation

“…Therefore, the use of CDV has an intrinsic weakness because, at conventional or higher dosages, from 1 to 10 mg/kg, the peak plasma concentration of CDV is inferior to the effective concentration against BKV in vitro. 19,20 Moreover, to reduce the risk of renal tubular toxicity, probenecid is generally associated with CDV when it is used at dosage of 3-5 mg/kg every 1-2 weeks while lower doses of 1 mg/kg 1-3 times a week without probenecid was shown to be efficacious and safe in single-center series. 13,21 Esterification of CDV with lipid ester derivative (hexadecyoxypropil, octadecyloxyethil and Probenecid was used in 7 out of 7 patients.…”

Characterization of Immunodominant BK Polyomavirus 9mer Epitope T Cell Responses

“…PyVAN and PyVHC have a significant impact on morbidity and graft and patient survival 11, 12, 13, 14, 15, 16, 17, 18. Despite considerable virologic research 19, 20, 21, 22, 23, randomized clinical studies either are lacking or failed to demonstrate effective antiviral therapies 24. In kidney transplantation (KT), high‐level BKPyV viruria and viremia have been identified as markers of progression to PyVAN 25, thus current management strategies recommend screening KTRs for viremia followed by reducing immunosuppression 26, 27, 28.…”