siRNAs Targeting Viral Protein 5: The Major Capsid Protein of Herpes Simplex Virus-1 Affects its Propagation and Cytoskeleton

Purpose: To investigate whether siRNA targeting viral protein 5 (VP5) can become a new treatment for herpes simplex virus type 1 (HSV-1).
Methods: Flow cytometry was performed to determine the ratio of siRNA and lipo2000 to reach the highest transfection efficiency. Western blot and q-PCR were performed to determine the knockdown efficiency of siRNA targeting UL19, as well as changes in cytoskeleton proteins. Plaque reduction assays and confocal microscopy were conducted to test the influence of VP5 knockdown on the HSV-1 life cycle and viral replication. F-actin organization was observed through confocal microscopy during HSV-1 infection when transfected with siRNA.
Results: Relative expression level of the UL19 gene dropped to 6 % while plaque formation inhibition rate rose to 85 % compared with virus control. Knocking down VP5 expression abrogated the changes to F-actin that were induced by HSV-1 infection.
Conclusion: Interfering with UL19 gene expression inhibits HSV-1 replication efficiently in vitro. The results indicate that the major capsid protein VP5 encoding gene UL19 may be a promising target for RNA interference-based therapeutic strategy against HSV-1.

Keywords
siRNA; Viral protein 5; Herpes simplex virus type 1; Gene expression; Propagation; Cytoskeleton rearrangement; F-actin; Transfection