| Certain DNA viruses cause diseases of major public health significance. Available treatments are of limited usefulness and more effective ones are needed. This work explores the possibility of using an engineered protein, namely a zinc-finger protein (ZFP), to inhibit viral DNA replication. Simian Vacuolating Agent 40 (SV40) DNA replication, in which the first step is the binding of the SV40 large T antigen (Tag) to the SV40 core origin of replication (SVcori), was used as a model system. To outcompete this binding, a three-finger protein with affinity for a sequence overlapping the Tag binding sites was constructed. The ZFP was shown to bind with high affinity and specificity to its target sequence GAGGCCGAG. When tested in cell extracts in vitro, and in the CV/EBNA and COS7 mammalian cell lines in culture, the protein extensively inhibited the replication of the pUC-HSO-NC plasmid, which harbors the SVcori. The negative control ZFPs NCZF, which binds with high affinity to a different 9-base pair sequence, and mSVZF, which binds with reduced affinity to GAGGCCGAG, caused comparatively little or no inhibition. These results suggest that an engineered ZFP is a possible strategy to counteract infections by DNA viruses. |
