Exploring the Antiviral Potential of Tungsten Oxide Nanoparticles Against Herpes Simplex Virus Type 1: A Promising Alternative to Acyclovir.

Herpes simplex virus type 1 (HSV-1) is responsible for the majority of cold sores, herpetic keratitis-induced blindness, profound skin lesions, and encephalitis that can be fatal. Currently, acyclovir and its derivatives are the first-line therapy for the treatment of HSV-1 infection. But there are drawbacks to these treatments: limited efficacy against drug-resistant strains of the virus. Hence, it is of critical importance to explore and develop new antiviral drugs for HSV-1. In the present study, we explored whether tungsten oxide nanoparticles (WO3NPs) were potent inhibitors of HSV-1 infection as a new class of agent. WO3NPs were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, and zeta potential analysis. Cytotoxicity of Vero cells caused by WO3NPs was determined by methyl thiazolyl tetrazolium (MTT) assay. The quantitative real-time polymerase chain reaction (qRT-PCR) assay was utilized for further verification of the action of the WO3NPs on HSV-1. The cytotoxicity test showed low toxicity (<20%) of the rod-shaped WO3NPs when they were assayed on Vero cells at concentrations of up to 700 μg/mL. When HSV-1 was treated with WO3NPs at 700 µg/mL [20% cytotoxicity concentration (CC20); the concentration causing 20% cytotoxicity, ~80% cell viability] and 1000 µg/mL [50% cytotoxicity concentration (CC50); the concentration causing 50% cytotoxicity, ~50% cell viability] for 3 h, the viral load was significantly reduced, achieving inhibition rates of 99.4% and 99.9%, respectively. Additionally, experiments conducted after HSV-1 infection of Vero cells (post-treatment assays) indicated that WO3NPs at concentrations of 250, 500, and 750 µg/mL significantly suppressed viral replication, with inhibition rates of 82%, 87.5%, and 96.5%, respectively. WO3NPs have potent inhibitory effects on HSV-1. Therefore, they can be considered potential candidates for therapeutic development against infections caused by this virus.