Design and In Vitro Evaluation of a Novel Antisense Oligonucleotide for Treatment of BK Virus Infection.

BK polyomavirus, a virus that latently resides in tubular epithelial cells of human kidneys, represents a major clinical problem for immunocompromised patients undergoing kidney transplantation. No proven effective specific antiviral therapies other than reduction of immunosuppressants exist. We exploited splice-modulating antisense oligonucleotides (ASOs) to block expression of the viral "gatekeeper protein" T antigen to specifically inhibit viral replication. Candidate oligonucleotides were screened for inhibitory activity in BK virus-infected cells, resulting in up to 97% reduction of viral T antigen mRNA and virus-encapsulating protein. The most promising ASO candidates were validated in BK virus-infected human kidney epithelial cells, showing sequence-specific activity that was exacerbated by chemical modifications. Administration of the candidate oligonucleotide in mice revealed long-lasting uptake in proximal tubules of the kidney, where BK virus resides. A final optimization round yielded an oligonucleotide displaying superior activity. Studies in transformed cells revealed a discernible shift in T antigen splicing not observed with a scrambled control, indicating that targeting of the donor splice site was responsible for the observed effects. Here, we demonstrate proof-of-principle for a direct-acting, splice-modulating, universal ASO that distributes to sites where BK viral replication occurs, warranting further development of this novel therapeutic to combat BK virus replication in kidney transplant patients.