Inhibition of clinical pathogenic herpes simplex virus 1 strains with enzymatically created siRNA pools

Herpes simplex virus (HSV) is a common human pathogen causing severe diseases such as encephalitis, keratitis, and neonatal herpes. There is no vaccine against HSV and the current antiviral chemotherapy fails to treat certain forms of the disease. Here, we evaluated the antiviral activity of enzymatically created small interfering (si)RNA pools against various pathogenic HSV strains as potential candidates for antiviral therapies. Pools of siRNA targeting 0.5-0.8 kbp of essential HSV genes UL54, UL29, or UL27 were enzymatically synthesized. Efficacy of inhibition of each siRNA pool was evaluated against multiple clinical isolates and laboratory wild type HSV-1 strains using three cell lines representing host tissues that support HSV-1 replication: epithelial, ocular, and cells that originated from the nervous system. The siRNA pools targeting UL54, UL29, and UL27, as well as their equimolar mixture, inhibited HSV replication, with the pool targeting UL29 having the most prominent antiviral effect. In contrast, the non-specific control siRNA pool did not have such an effect. Moreover, the UL29 pool elicited only a minimal innate immune response in the HSV-infected cells, thus evidencing the safety of its potential clinical use. These results are promising for the development of a topical RNA interference approach for clinical treatment of HSV infection. J. Med. Virol. 88:2196-2205, 2016. © 2016 Wiley Periodicals, Inc.