Activity of Propolis Nanoparticles against HSV-2: Promising Approach to Inhibiting Infection and Replication.

Herpes simplex type 2 (HSV-2) infection causes a significant life-long disease. Long-term side effects of antiviral drugs can lead to the emergence of drug resistance. Thus, propolis, a natural product derived from beehives, has been proposed to prevent or treat HSV-2 infections. Unfortunately, therapeutic applications of propolis are still limited due its poor solubility. To overcome this, a nanoparticle-based drug delivery system was employed. An ethanolic extract of propolis (EEP) was encapsulated in nanoparticles composed of poly(lactic-co-glycolic acid) and chitosan using a modified oil-in-water single emulsion by using the solvent evaporation method. The produced nanoparticles (EEP-NPs) had a spherical shape with a size of ~450 nm and presented satisfactory physicochemical properties, including positively charged surface (38.05 ± 7.65 mV), high entrapment efficiency (79.89 ± 13.92%), and sustained release profile. Moreover, EEP-NPs were less cytotoxic on Vero cells and exhibited anti-HSV-2 activity. EEP-NPs had a direct effect on the inactivation of viral particles, and also disrupted the virion entry and release from the host cells. A significant decrease in the expression levels of the HSV-2 replication-related genes (ICP4, ICP27, and gB) was also observed. Our study suggests that EEP-NPs provide a strong anti-HSV-2 activity and serve as a promising platform for the treatment of HSV-2 infections.